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The aerodynamic characteristics of road vehicles in windy environments are the prerequisites for the evaluation and prediction of the driving safety and stability. To investigate the aerodynamic characteristics of the overtaking vehicles on the bridge deck under the effects of crosswinds, models of a cable-stayed bridge with a typical flat box girder and road vehicles involving articulated lorry and commercial van with a scale of 1 : 40 were tested in the wind tunnel laboratory. A series of tests figured out the variation of the aerodynamic forces of road vehicles during the overtaking process after considering the aerodynamic interference between lorry and lorry, van and van, and lorry and van. Additionally, the influence of the lateral overtaking distance between the overtaking vehicles was regarded as well. The result reveals the upstream vehicle has a significant influence on the aerodynamic coefficients of the downstream vehicle, which have experienced dramatic fluctuations during the overtaking process, and the various shapes of the aerodynamic coefficients are highly dependent on it.

The typical response to the lowering of plasma Na+ concentration and blood pressure in our body involves the release of aldosterone from the adrenal glands, which triggers the reabsorption of sodium in the kidney. Although the effects of aldosterone on this physiological mechanism were extensively studied in the past decades, there are still some aspects to be fully elucidated. In the present study, we propose for the first time a new approach based on Raman spectroscopy to monitor the ionic activity in aldosterone-treated A6 renal epithelial cells. This spectroscopic technique is capable of probing the cells through their thickness in a non-destructive and nimble way. The spectroscopic variations of the Raman bands associated to the O-H stretching of water were correlated to the variations of ionic concentration in the intracellular and extracellular fluids. The increase of Na+ concentration gradients was clearly visualized in the cytosol of aldosterone-treated cells. The enhancement of the Na+ current density induced by aldosterone was estimated from the variation of the ionic chemical potential across the intracellular space. In addition, the variation of the O-H Raman bands of water was used to quantify the cell thickness, which was not affected by aldosterone.

This paper proposes a novel inerter-based component dynamic vibration absorber, namely, electromagnetic resonant shunt tuned mass-damper-inerter (ERS-TMDI). To analyze the performances of the ERS-TMDI, the combined ERS-TMDI and a single degree of freedom system are developed. The h(2) norm performances of the ERS-TMDI, whose aim is to minimize the root mean square (RMS) value of structure damage under random ground acceleration excitation, are introduced in comparison with the energy-harvesting series electromagnetic tuned mass dampers (ERS-TMDs), tuned mass-damper-inerter (TMDI) and the classical tuned mass damper (TMD). The closed-form solutions, including the optimal mechanical tuning ratio, the optimal electrical damping ratio, the optimal electrical tuning ratio and the optimal electromagnetic mechanical coupling coefficient, are obtained. It is shown that the ERS-TMDI is superior to both the classical TMD and the ERS-TMD systems for protection from structure damage. Specifically, from the frequency-domain analyses, a case study is performed to illustrate the effectiveness, robustness of the ERS-TMDI and the sensitivity to the parameter changes. From the time-domain analyses, four types of earthquakes are studied to demonstrate the performances of vibration suppression. National Key Basic Research Scheme of China (973 Program) [2015CB057702]; National Natural Science Foundation of China [51508185, 51378203]; Natural Science Foundation of Hunan Province of China [2015JJ3073]; China Scholarship Council This work was supported by National Key Basic Research Scheme of China (973 Program) under Grant 2015CB057702, National Natural Science Foundation of China under Grant 51508185 and 51378203, and Natural Science Foundation of Hunan Province of China under Grant 2015JJ3073. The author Hongxin Sun is also grateful to the financial support from China Scholarship Council to conduct research as a visiting scholar in Lei Zuo's Lab at Virginia Tech.

The time-delayed displacement feedback control is provided to restrain the superharmonic and subharmonic response of the elastic support beams. The nonlinear equations of the controlled elastic beam are obtained with the help of the Euler&ndash, Bernoulli beam principle and time-delayed feedback control strategy. Based on Galerkin method, the discrete nonlinear time-delayed equations are derived. Using the multiscale method, the first-order approximate solutions and stability conditions of three superharmonic and 1/3 subharmonic resonance response on controlled beams are derived. The influence of time-delayed parameters and control gain are obtained. The results show that the time-delayed displacement feedback control can effectively suppress the superharmonic and subharmonic resonance response. Selecting reasonably the time-delayed quantity and control gain can avoid the resonance region and unstable multi-solutions and improve the efficiency of the vibration control. Furthermore, with the purpose of suppressing the amplitude peak and governing the resonance stability, appropriate feedback gain and time delay are derived.

Three-dimensional (3D) hierarchical flower-like Mg–Al-layered double hydroxides (MA-LDHs) with Mg:Al mole ratio of 100:40, 100:50, 100:60 were fabricated by a simple hydrothermal method using the sodium dodecyl sulfate (SDS) as the template and intercalation layer. The hierarchical porous nanostructures provided natural channels for effective and fast transporting carriers. The MA-LDHs with Mg:Al mole ratio of 100:50 (Mg–Al-LDHs-5) exhibited fast response and recovery time of 1.3 s and 30 s to 100 ppm NO x at room temperature (RT). The enhanced response of Mg–Al-LDHs-5 could be attributed to the unique hierarchical porous structure and gallery pathway. The formation mechanism of the 3D flower-like MA-LDHs was proposed.

The time-delayed velocity and acceleration feedback control are provided to mitigate the resonances response of a nonlinear dynamic beam. By use of the method of multiple scales, the primary resonance and the 1/3 subharmonic resonance response of the controlled beam are analyzed. The excitation amplitude response peak and critical expression are obtained, and numerical simulations are also given. The effect of the feedback gains and time delayed on the steady-state response of the two types of resonances are investigated. The result show that time-delayed acceleration feedback control can effectively mitigate amplitude, and the main resonance response is affected periodically. Selecting reasonable control gain and time delay quantity can avoid the main resonance region and unstable multi-solutions, and can improve the efficiency of the vibration control.

This paper studies the nonlinear primary resonance in the vibration control of cable-stayed beam with time delay feedback. Considering the continuity conditions, the in-plane nonlinear motion equations of the cable-stayed beam are obtained via the Hamilton principle. Then, utilizing the method of multiple scales, the modulation equations that govern the nonlinear dynamics of the cable-stayed beam are derived. These equations are then utilized to investigate the effect of control gain and time delay on the amplitude and frequency response behavior. Depending on the excitation amplitude and the commensurability of the delayed-response frequency to the excitation frequency, it can be demonstrated that appropriate choice for the feedback gain can greatly reduce the response amplitude of the primary resonance. Finally, numerical simulation is also given to determine the optimal value for control gain and time delays that can improve the vibrations suppression efficiency.

Distribution network usually refers to the rated voltage of 110KV and below, and the function of direct power supply to users in the power system. The reliability of distribution network power supply directly affects the safety and economy of electricity use. In recent years, with the development of the national economy, the power load has greatly increased. In some areas, the construction of distribution networks cannot keep up with the increase in power load, resulting in power outages and frequent power failures in some regions. At the same time, users are increasingly demanding power quality. Whether the dispatcher or the user is eager to quantify the safety and economic analysis of the distribution network, the accuracy and level of the decision making of the intelligent distribution network dispatcher are improved. Studying the short-circuit fault and single-phase-to-ground fault fast fault location scheme is of great significance to improving the reliability of the distribution network operation. Self-healing is one of the main functions for the safe and reliable operation of smart grids. Reliable detection is the basis for realizing the self-healing function. The probability of a single-phase earth fault in a distribution network is very high because I mostly use it for neutral point grounding in medium-voltage distribution networks and use arc-suppression coils for grounding. When single-phase earthed, it is difficult to find point failures. At present, the small current ground fault line selection technology has been basically mature, and the small current ground fault location technology has achieved good results in the field of transient signals. Based on the transient characteristics of transient components, the single-phase ground fault location technology of power distribution network and the transient characteristics of single-phase grounded neutral distribution network are studied. At the same time, single-phase ground fault detection and cross-section based on parameter identification and current abrupt change are explained. Positioning method, implementation technology of single-phase earth fault feature detection function of distribution automation terminal, and architecture, interface mode and implementation method of single-phase positioning application software for distribution network.

This paper proposes a novel inerter-based dynamic vibration absorber, namely, electromagnetic resonant shunt tuned mass-damper-inerter (ERS-TMDI). To obtain the performances of the ERS-TMDI, the combined ERS-TMDI and a single degree of freedom system are introduced. H2 criteria performances of the ERS-TMDI are introduced in comparison with the classical tuned mass-damper (TMD), the electromagnetic resonant shunt series TMDs (ERS-TMDs), and series-type double-mass TMDs with the aim to minimize structure damage and simultaneously harvest energy under random wind excitation. The closed form solutions, including the mechanical tuning ratio, the electrical damping ratio, the electrical tuning ratio, and the electromagnetic mechanical coupling coefficient, are obtained. It is shown that the ERS-TMDI is superior to the classical TMD, ERS-TMDs, and series-type double-mass TMDs systems for protection from structure damage. Meanwhile, in the time domain, a case study of Taipei 101 tower is presented to demonstrate the dual functions of vibration suppression and energy harvesting based on the simulation fluctuating wind series, which is generated by the inverse fast Fourier transform method. The effectiveness and robustness of ERS-TMDI in the frequency and time domain are illustrated.

This paper proposes two types of base isolation systems with tuned inerter dampers (TID) composed of a spring, an inerter and a dashpot in serial or parallel to enhance the seismic isolation performance of the traditional base-isolation system. The TID isolation systems are optimally tuned using the H2 norm criterion to achieve the best RMS vibration performance under white-noise random excitation. The TID frequency ratio and damping ratio are defined as the design parameters, whose optimal values are analytically derived for the undamped primary system and numerically verified. The results show that the optimum exists in the serial TID isolation system (inerter and dashpot in serial layout), while in the parallel TID isolation system (inerter and dashpot in parallel layout) larger TID stiffness and larger TID damping are preferred in practice to achieve better isolation performance. The isolation performance of the H2 optimal TID systems is also compared with that of the H∞ optimized systems obtained numerically. The results suggest that the optimal serial TID system has overall better isolation performance over the broad frequency range, which is preferable for seismic vibration isolation because seismic waves usually contain a wide range of frequency components. The parallel TID system cannot be tuned optimally for practical structures, nevertheless, it still achieves better isolation performance at the resonant vibrations by an appropriate selection of the design parameters. The influence of the structural parameters on the tuning parameters are studied. Numerical case studies are conducted in comparison with the traditional and tuned mass damper (TMD) isolation systems for a five-story laboratory building prototype. The potential power in the TID isolations that could be converted to usable electricity in earthquakes are also examined.

The paper presents time-delayed feedback control to reduce the nonlinear resonant vibration of a piezoelectric elastic beam.a#13; Specially, we examine three single-input linear time-delayed feedback control methodologies: displacement, velocity anda#13; acceleration time-delayed feedback. Moreover, the multi-input time-delayed feedback control methodologies are discussed. Utilizinga#13; the method of multiple scales, the modulation equation and the first order approximations of the primary resonances are derived and the effect of time delay on the resonances is analyzed. Then the effect of time delays and control gains on the stability, amplitude,a#13; frequency-response behavior, peak amplitude, critical excitation amplitude are investigated. Optimal values of the controllers gainsa#13; and delay are obtained, simulated, and compared. The time-delayed feedback control acts as a vibration absorber at specific values of time delay. On the other hand, using using mixed delay feedback controllers demonstrates an excellent improvement in mitigating the first-mode vibration.

Regulation of intracellular pH is critically important for many cellular functions. The quantification of proton extrusion in different types of cells and physiological conditions is pivotal to fully elucidate the mechanisms of pH homeostasis. Here we show the use of gold nanoparticles (AuNP) to create a high spatial resolution sensor for measuring extracellular pH in proximity of the cell membrane. We test the sensor on HepG2 liver cancer cells and MKN28 gastric cancer cells before and after inhibition of Na+/H+ exchanger. The gold surface conjugation strategy is conceived with a twofold purpose: i) to anchor the AuNP to the membrane proteins and ii) to quantify the local pH from AuNP using surface enhanced Raman spectroscopy (SERS). The nanometer size of the cell membrane anchored sensor and the use of SERS enable us to visualize highly localized variation of pH induced by H+ extrusion, which is particularly upregulated in cancer cells., Understanding the pH changes at cell surfaces is important for understanding the mechanisms of different physiological processes. Here, the authors report on the development of a cell membrane anchored gold nanoparticle for surface enhanced Raman spectroscopy determination of pH.