Search

The relative position sensor of a high-speed maglev train is an important part of train location and speed detection for motor traction, but its output signal is not only related to position but also related to the suspension gap of the maglev train. The fluctuation of the suspension gap will affect the amplitude of the output signal of the sensor (i.e., the suspension wave signal is coupled with the output signal). The prediction normalization method currently used can eliminate the effect of the suspension fluctuation to a certain extent, but there is a limitation. Aiming at this problem, this paper analyzes the frequency characteristics of the suspension gap fluctuation caused by track irregularities and proposes a gap estimation algorithm based on the adaptive filter. The Kalman filter is used to estimate the gap and then the output signal is compensated according to the numerical relationship between the gap and the output signal of the sensor, so as to achieve the decoupling between the gap and the position measurement. Finally, the effectiveness of the method is proved by the comparison experiments.

Organic π-conjugated polymers (CPs) have been intensively explored for a variety of critical photocatalytic applications in the past few years. Nevertheless, CPs for efficient CO2 photoreduction have been rarely reported, which is mainly due to the lack of suitable polymers with sufficient solar light harvesting ability, appropriate energy level alignment and good activity and selectivity in multi-electron-transfer photoreduction of CO2 reaction. We report here the rational design and synthesis of two novel triphenylamine (TPA) based conjugated microporous polymers (CMPs), which can efficiently catalyze the reduction of CO2 to CO using water vapor as an electron donor under ambient conditions without adding any co-catalyst. Nearly 100% selectivity and a high CO production rate of 37.15 μmol h−1 g−1 are obtained for OXD-TPA, which is significantly better than that for BP-TPA (0.9 μmol h−1 g−1) as a result of co-monomer change from biphenyl to 2,5-diphenyl-1,3,4-oxadiazole. This difference could be mainly ascribed to the synergistic effect of a decreased optical band gap, improved interface charge transfer and increased CO2 uptake for OXD-TPA. This contribution is expected to spur further interest in the rational design of porous conjugated polymers for CO2 photoreduction. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore) Accepted version

Three new boron ketoiminate-based conjugated polymers P1, P2, and P3 were designed and synthesized through the Sonogashira coupling reaction of 4,6-bis(4-bromophenyl)-2,2-difluoro-3-phenyl-2H-1,3,2-oxazaborinin-3-ium-2-uide (M1) with 1,4-diethynyl-2,5-bis(octyloxy)benzene (M2), 3,6-diethynyl-9-octyl-9H-carbazole (M3) and 3,7-diethynyl-10-octyl-10H-phenothiazine-S,S-dioxide (M4), respectively. All the resulting polymers showed obvious aggregation-induced emission (AIE) behaviours. Interestingly, it was found that a great difference in the electron-donating abilities of the D–A type polymer linkers can lead to the unique AIE behaviour of the alternating polymers in the aggregate state, which provides us with a practical strategy to design tunable AIE-active conjugated polymers. Most importantly, studies on MCF-7 breast cancer cell imaging revealed that the nanoparticles fabricated from the conjugated polymers could serve as promising fluorescent probes with low cytotoxicity and high photostability.

In marine nuclear power plants based on molten salt reactors, the complexity of core nuclear reactions, fuel fluidity, and the “false” water level characteristics of the steam generator water level make it unrealistic to establish an accurate mathematical model, so it is difficult to implement traditional PID control methods. This has increased substantially. The fuzzy control has a good solution to this feature. Therefore, combined with the fuzzy control that does not depend on the precise mathematical model of the controlled object, the fuzzy controller of the nuclear power plant is designed, and the control research of the core power is obtained respectively through MATLAB/Simulink simulation. It shows that the designed fuzzy controller can achieve good control of nuclear power plants.

Within a total residence time of 9 min, the sodium salt of ciprofloxacin was prepared from simple building blocks via a linear sequence of six chemical reactions in five flow reactors. Sequential offline acidifications and filtrations afforded ciprofloxacin and ciprofloxacin hydrochloride. The overall yield of the eight‐step sequence was 60 %. No separation of intermediates was required throughout the synthesis when a single acylation reaction was applied to remove the main byproduct, dimethylamine., United States. Defense Advanced Research Projects Agency (Grant N666001-11-C-4005)

A three-component, titanium-mediated synthesis of α-branched N-acylamines from commercial or readily accessible amides, aldehydes, and organometallic reagents is reported. The transformation proceeds under mild reaction conditions and tolerates a variety of functional groups (including nitrile, carbamate, olefin, basic amine, furan, and other sensitive heteroaromatics) to generate a large umbrella of α-branched N-acylamine products in high yields. The operationally practical procedure enables the use of this method in parallel chemical synthesis, a valuable feature that can facilitate the screening of bioactive molecules by medicinal chemists.

The ability to transform two-dimensional (2D) materials into a three-dimensional (3D) structure while preserving their unique inherent properties might offer great enticing opportunities in the development of diverse applications for next generation micro/nanodevices. Here, a self-assembly process is introduced for building free-standing 3D, micro/nanoscale, hollow, polyhedral structures configured with a few layers of graphene-based materials: graphene and graphene oxide. The 3D structures have been further modified with surface patterning, realized through the inclusion of metal patterns on their 3D surfaces. The 3D geometry leads to a nontrivial spatial distribution of strong electric fields (volumetric light confinement) induced by 3D plasmon hybridization on the surface of the graphene forming the 3D structures. Due to coupling in all directions, resulting in 3D plasmon hybridization, the 3D closed box graphene generates a highly confined electric field within as well as outside of the cubes. Moreover, since the uniform coupling reduces the decay of the field enhancement away from the surface, the confined electric field inside of the 3D structure shows two orders of magnitude higher than that of 2D graphene before transformation into the 3D structure. Therefore, these structures might be used for detection of target substances (not limited to only the graphene surfaces, but using the entire volume formed by the 3D graphene-based structure) in sensor applications.

The relative position sensor provides phase angle information for the traction system. The failure of the sensors directly affects whether the train can operate normally. Based on the analysis of the sensor, the common faults of the sensor are analyzed, and the corresponding fault features are extracted. The fault characteristics of the sensor are presented. Based on the research of the decision tree fault diagnosis method, the improved decision tree based on support vector machine is proposed to realize the fault diagnosis and improve the effect of the diagnosis. Finally, the fault diagnosis platform is designed, and the tests show that the improved decision tree has high diagnosis correct rate.

Precision positioning platform is the key component of semiconductor lithography and precision manufacturing. In this paper, a multi-degree-of-freedom maglev precise positioning platform with a wide range of travel is studied, and the three-degree-of-freedom dynamic modeling and decoupling control of the platform suspension system are studied. The sliding mode variable structure control strategy is introduced to decouple the three-degree-of-freedom coupled system, and the extended state observer is introduced to observe the internal and external disturbances of the system. Using the the three-point levitation system in the laboratory, the control algorithm of the levitation controller of the positioning platform is designed and implemented. The specific experimental results are given and compared.

This paper mainly studies the signal processing problem of position and speed measurement system for the highspeed maglev train. The signals of relative positioning sensors and absolute positioning sensors are fused by the multi-sensor fusion algorithm. A multi-sensor fusion algorithm based on adaptively weighted fusion is proposed and the problem of distortion on magnetic pole phase when sensor passing through the track joints is solved. The signal processing scheme of the position and speed measurement system is implemented systematically. The experimental results verify the feasibility and validity of the proposed signal processing algorithm and scheme.

Position speed detection technology is the key technology of high speed maglev train traction and control system. Signal processing unit is crucial for position speed detection technology. This paper introduces the structural framework of the signal processing part of the position speed detection system. The signal processing of the relative and absolute sensors is described. The internal signal transmission between the crate and the sensors is presented. And the tests are given to validate the performance of system.

In order to improve maintenance efficiency, reduce maintenance costs, reduce the workload of maintenance personnel, and avoid huge economic losses and catastrophic accidents, this paper designs a prognostic and health management (PHM) architecture of maglev train based on distributed hierarchical structure. First, the system is used as a unit to establish a distributed structure, and the hierarchy is divided according to the structure of "train-vehicle-system-subsystem". Then, the data of the maglev train is divided by the hierarchical structure, and the subsystem fault detection model and health assessment model are established, and the system fault diagnosis model and fault prediction model are further established. Based on the fault diagnosis or fault prediction results, the optimal maintenance decision is provided. Finally, a PHM architecture of maglev train based on a distributed and hierarchical structure is proposed.

A series of Sn2+ doped MgIn2S4 photocatalysts were prepared via a facial hydrothermal method. The Sn dopants substitute the sites of Mg atom in MgIn2S4 unit cell, but not alter the crystal structure, demonstrated by the results of XRD and XPS. Compared to pristine MgIn2S4, Sn-doped MgIn2S4 samples exhibit significantly enhanced photocatalytic CO2 reduction activity. With increasing the Sn dopant content, the CO2 conversion rate first ascends, achieving the maximum rate at Sn-MgIn2S4-2 sample, and then decreases. After illumination for 4 h, the highest yield of CO and CH4 for Sn-MgIn2S4-2 sample reaches about 3.35 and 3.33 times higher than that of pristine MgIn2S4. The theoretical results based on density functional theory calculations reveal that Sn doping in MgIn2S4 tunes the band structure from the direct-transition of MgIn2S4 to indirect-transition, diminishes band gap and extends the light absorption range, reduces the effective masses of holes and promotes the migration of photoinduced carriers. The experimental results also demonstrate the positive role of Sn dopant in accelerating the separation and transportation of charges, and improving CO2 adsorption ability. This work systematically investigates and discusses the Sn2+ doping effect in MgIn2S4 on crystal structure, lattice variations, electronic band structures, CO2 adsorption ability, and photocatalytic CO2 reduction activity, which can provide a new hint for the fabrication of efficient photocatalyst by metal ion doping.

The numerical simulation analysis of the fluid-solid coupling of the ship’s boring water-lubricated bearing is carried out to study the influence law of the inclination and eccentricity of the rotating shaft on the pressure distribution and fluid flow state in the bearing. The results show that the tilt of the rotating shaft changes the shape of the inner flow passage of the water-lubricated bearing, resulting in unstable flow in the bearing. When rotating shaft is in normal, the pressure value in the water-lubricated bearing decreases first and then increases in the axial direction. However, after the rotation of the shaft is tilted, the change of the pressure value is the opposite; the stress of the rubber layer generally shows an increasing trend with the increase of the inclination angle.

Convert inert CO2 into chemical fuel via photocatalytic reduction is very intriguing. However, high charge recombination rate and inadequate CO2 absorption severely impede photocatalytic CO2 reduction activity. To address these drawbacks, we developed a strategy of MgIn2S4 modification by carbon. Two types of photocatalysts with carbon modifications, carbon-coated MgIn2S4 (MgIn2S4-SC); carbon coating and doping MgIn2S4 (MgIn2S4-Cx), were obtained and exhibited significantly enhanced catalytic activity. The CO evolution rate of MgIn2S4-C2 and MgIn2S4-SC reached 19.5 and 7.03 times higher than that of unmodified MgIn2S4, respectively. Our experimental and theoretical results disclosed that doped carbon for MgIn2S4 could prevent charge recombination in the bulk, facilitate CO2 adsorption, and decrease photocatalytic reaction energy barrier, while coated carbon could accelerate surface carrier migration, but had smaller and greater effect on fascinating CO2 adsorption and decreasing reaction energy barrier. The synergistic effect of surface coated and bulk doped carbon could maximize the photocatalysis efficiency.

Photoelectrochemical water splitting over semiconductors offers a sustainable solar light conversion technique capable of alleviating worldwide energy crisis. Conjugated polymers have recently received increasing attention as a class of promising photoelectrode materials due to their advantages of earth-abundance, non-toxicity, light weight, and molecularly tunable functionalities, etc. However, the development of highly efficient organic photoelectrodes remains a big challenge. In this study, two covalent organic frameworks (COFs) incorporated 2,4,6-triphenyl-1,3,5-triazine are demonstrated as excellent photocathodes for H production. By introducing 2,4,6-triphenylbenene to properly create donor/acceptor pairs within COF, a significantly enhanced visible-light photocurrent of TAPB-TTB COF (110 µA cm ) compared to TTA-TTB COF (35 µA cm ) at 0 V versus reversible hydrogen electrode (RHE) is obtained without adding organic sacrificial agent and metal cocatalysts (>420 nm). The enhanced photocurrent density is attributed to the narrowed bandgap and improved charge transfer by intramolecular donor–acceptor combination. This work highlights the great promising applications of crystalline donor–acceptor COFs as high-efficiency organic photoelectrode for water splitting. Ministry of Education (MOE) National Research Foundation (NRF) Accepted version Financial work was provided by the Singapore National Research Foundation (grant no. R279-000-444-281), the National 11 University of Singapore (grant no. R279-000-482-133), Research Foundation for Advanced Talents of East China University of Technology (No. DHBK201927), National Science Foundation for Young Scientists of China (grant no. 21905122), National Science Foundation of Jiangxi province of China (No. 20202BAB203007). D. J. acknowledges supports by MOE tier 1 grant (R-143-000-A71-114) and NUS start-up grant (R-143-000-A28-133). C. X. thanks the support from the Ministry of Education, Singapore, under AcRF-Tier2 (MOE2018-T2-1- 017) and AcRF-Tier1 (MOE2019-T1-002-012, RG102/19).

Binary metal oxides have been considered as promising anode materials, which exhibit much better performances than single metal oxides in view of their variable oxidation state and fairly high electrical conductivity. In this research, NiCo2O4 nanocrystals are prepared from a facile procedure including microemulsion-solvothermal reaction and subsequent calcination at 400 °C for 4 hours. The as-prepared NiCo2O4 nanocrystals are characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). When applied as an anode for a lithium ion battery, it demonstrates excellent cycling and rate stability. The initial charge/discharge efficiency is as high as 75.41% at a current density of 100 mA g−1. After 45 cycles, the discharge capacity still retains up to 1175.9 mA h g−1, which is even much higher than that of the initial discharge capacity. Meanwhile, the reversible capacity remains over 644.9 mA h g−1 at a large current density of 1600 mA g−1, ascribed to the dispersed nanoparticles, which will help to improve the conductivity of the electrode material during the lithium-ion insertion/deintercalation process, shorten the ion diffusion path and reduce the charge transfer resistance (Rct).

Three D-π-A 1,4-dihydropyridine derivatives with aggregation-induced emission characteristics were synthesized. The molecules comprise of a 4-(dimethylamino)styryl group as the electron donor group and different end groups, dicyanomethylene, vinylcyanoacetate, and 2-methylene-1H-indene-1,3(2H)-dione, as the electron acceptor, respectively. These target compounds display different stimulus-responsive fluorescent properties in the solid state. The original samples with the dicyanomethylene and vinylcyanoacetate groups do not show fluorescence color changes in response to external force stimuli, whereas the compound containing the 2-methylene-1H-indene-1,3(2H)-dione unit exhibits reversible piezochromism and solvent-induced emission changes due to the transformation between the crystalline and amorphous states, which can be ascribed to their different molecular stacking mode in the solid state. Furthermore, these compounds show different acid/base-induced solid-state fluorescence switching properties due to the different sites of the protonation. Additionally, all of the derivatives can be fabricated into biocompatible fluorescent nanoparticles and used for MCF-7 cell imaging.

Cleavage of carbon–halogen bonds via either single-electron reduction or atom transfer is a powerful transformation in the construction of complex molecules. In particular, mild, selective hydrodehalogenations provide an excellent follow-up to the application of halogen atoms as directing groups or the utilization of atom transfer radical addition (ATRA) chemistry for the production of hydrocarbons. Here we combine the mechanistic properties of photoredox catalysis and silane-mediated atom transfer chemistry to accomplish the hydrodebromination of carbon–bromide bonds. The resulting method is performed under visible light irradiation in an open vessel and is capable of the efficient reduction of a variety of unactivated alkyl and aryl substrates.

This paper presents a double-tube once-through steam generator (DOTSG), whose tube unit includes an outer straight tube and an inner helical tube, in an integral pressurized water reactor (IPWR). To obtain the optimum structure of the inner helical tube and the arrangement of DOTSGs in the reactor pressure vessel, a two-level optimization method is used, aiming at the lower pumping power needed, and a smaller reactor pressure vessel volume is used. The pitch of inner helical tubes and the central distance of outer tubes are considered design parameters when minimizing the pumping power with the genetic algorithm in the bottom level, while the number of tube units in a single DOTSG and the number of DOTSGs in the reactor pressure vessel (RPV) are optimized to obtain the minimum volume of the IPWR, which is conducted in the top level. The optimum pitch of the helical tube varies in the sub-cooled region, boiling region and superheated region. The results show that the smaller pitch brings a shorter tube length and a higher pressure drop, and the effects are strong in the sub-cooled region and the superheated region but weak in the boiling region. In this way, the optimal structure of the inner helical tube is a small pitch in the single-phase region and a large pitch in the boiling region. According to the bottom level results, the optimum arrangement of DOTSGs in the pressure vessel is determined.

In order to improve the efficiency of ship pipeline vibration isolation, an optimized design scheme of coated rubber vibration isolator was proposed. The natural frequency was calculated and a test bench was established for vibration isolation performance test. The results show that the dynamic and static stiffness of the optimized vibration isolator is significantly lower than the traditional design value at the natural frequency. The natural frequency of the vibration isolator is reduced from about 35Hz to about 9.7Hz from the initial design scheme, and the vibration isolation efficiency is increased from about 20dB to about 33dB as well.

The limited spatial coverage of the plasmon enhanced near-field in 2D graphene ribbons presents a major hurdle in practical applications. In this study, diverse self-assembled 3D graphene architectures are explored that induce hybridized plasmon modes by simultaneous in-plane and out-of-plane coupling to overcome the limited coverage in 2D ribbons. While 2D graphene can only demonstrate in-plane, bidirectional coupling through the edges, 3D architectures benefit from fully symmetric 360° coupling at the apex of pyramidal graphene, orthogonal four-directional coupling in cubic graphene, and uniform cross-sectional radial coupling in tubular graphene. The 3D coupled vertices, edges, surfaces, and volume induce corresponding enhancement modes that are highly dependent on the shape and dimensions comprising the 3D geometries. The hybridized modes introduced through the 3D coupling amplify the limited plasmon response in 2D ribbons to deliver nondiffusion limited sensors, high efficiency fuel cells, and extreme propagation length optical interconnects.

Pre-treatment of graphitic carbon nitride (GCN) with H2O2 introduces active C–OH groups that can react with HAuCl4 to immobilize single atom Au(I) in the GCN matrix through creating robust Au(I)–O coordination bonds. This strong bonding can effectively restrict the diffusion of intermediate Au(0) towards the formation of Au particles during the photocatalytic hydrogen evolution process. As such, the single atom Au(I) incorporated GCN maintained superior activities with excellent stabilities for photocatalytic hydrogen generation. Accepted version

Conjugated polymer-based photocatalysts have shown great potential in H2 production via water splitting, but an intrinsic drawback of conventional hydrophobic polymer photocatalysts is their poor wettability and relatively large particle size in aqueous media, which is favorable for charge recombination with limited interfacial reaction efficiency. Herein, a well-dispersed organic water reduction system using cationic conjugated polyelectrolyte as the photocatalyst has been reported for the first time. In comparison to a model polymer (PFBT) bearing the same conjugated backbone, the polyelectrolyte exhibits significantly enhanced photocatalytic efficiency due to the extended light absorption and improved charge separation of the polymer aggregates. Ministry of Education (MOE) National Research Foundation (NRF) Accepted version This work was financially supported by the Singapore National Research Foundation (R279-000-444-281 and R279-000-483-281), National Univer- sity of Singapore (R279-000-482-133), Singapore MOE AcRF-Tier1 (RG 12/15), Singapore MOE AcRF-Tier1 (2016-T1-002-087, RG 120/16), and AcRF-Tier2 (MOE2016-T2-2-056).

This paper takes the magnetic suspension test vehicle model as the research obj ect and establishes the dynamic model of single electromagnet. In order to overcome the large hysteresis caused by inductance change and improve the dynamic response performance, a current loop is added to the system. A fuzzy adaptive PID controller is designed for the electromagnet model with strong nonlinearity and model uncertainty. Simulation and experiment demonstrate that the controller can markedly improve the control performance of the magnetic suspension test vehicle model system, make the overshoot of the system smaller, and have better anti-interference ability and faster response speed.

The mid-speed maglev train adopts synchronous traction. Only the real-time acquisition of the position and speed information of the train can realize the closed-loop traction of the train. The signal processing of the position and speed detection unit of the train is directly related to the accuracy of the position and speed information. The comparison and analysis of three kinds of signal processing methods, such as amplitude extraction method based on envelope detection, phase extraction method based on XOR comparison and position information extraction method based on synchronous demodulation, show that the signal processing based on synchronous demodulation has obvious advantages. This paper proposes synchronous demodulation based on phase-locked loop. The demodulation method proves that synchronous demodulation based on phase-locked loop method can simultaneously demodulate both the amplitude and phase information in the signal, and can effectively suppress the influence of the traction traveling wave, and has strong noise reduction capability.

Explosive charging vehicles with functionality of vertical motion and horizontal motion are widely applied in the field of tunnel construction for its convenience and flexibility in limited space. Conventional PID control methodology explore every single joints separately in multi joints system and design a PID controller for every joint, which leads the control system complex and time-consuming. A novel dynamics based PID control methodology is proposed, which combines dynamics compensation and PID signal together in the controller to eliminate final position error. The described control method is operated on an explosive charging vehicle and indicates that the end-effector can be manipulated with precision.

The assembly of two-dimensional (2D) graphene into three-dimensional (3D) polyhedral structures while preserving the graphene's excellent inherent properties has been of great interest for the development of novel device applications. Here, fabrication of 3D, microscale, hollow polyhedrons (cubes) consisting of a few layers of 2D graphene or graphene oxide sheets via an origami-like self-folding process is described. This method involves the use of polymer frames and hinges, and aluminum oxide/chromium protection layers that reduce tensile, spatial, and surface tension stresses on the graphene-based membranes when the 2D nets are transformed into 3D cubes. The process offers control of the size and shape of the structures as well as parallel production. In addition, this approach allows the creation of surface modifications by metal patterning on each face of the 3D cubes. Raman spectroscopy studies show the method allows the preservation of the intrinsic properties of the graphene-based membranes, demonstrating the robustness of our method.

Thermal reflow of polymers is a well-established phenomenon that has been used in various microfabrication processes. However, present techniques have critical limitations in controlling the various attributes of polymer reflow, such as the position and extent of reflow, especially at the nanoscale. These challenges primarily result from the reflow heat source supplying heat energy to the entire substrate rather than a specific area. In this work, a focused ion beam (FIB) microscope is used to achieve controllable localized heat generation, leading to precise control over the nanoscale polymer reflow. Through the use of the patterning capability of FIB microscopy, dramatically different reflow performances within nanoscale distances of each other are demonstrated in both discrete periodic and continuous polymer structures. Further, we utilize a self-assembly process induced by nanoscale polymer reflow to realize 3D optical devices, specifically, vertically aligned nanoresonators and graphene-based nanocubes. HFSS and Comsol simulations have been carried out to analyze the advantages of the polymer-based 3D metamaterials as opposed to those fabricated with a metallic hinge. The simulation results clearly demonstrate that the polymer hinges have a dual advantage; first, the removal of any interference from the transmission spectrum leading to strong and distinct resonance peaks and, second, the elimination of parasitic leeching of the enhanced field by the metallic hinge resulting in stronger volumetric enhancement. Thus, the 2-fold advantages existing in 3D polymer-hinge optical metamaterials can open pathways for applications in 3D optoelectronic devices and sensors, vibrational molecular spectroscopy, and other nanoscale 3D plasmonic devices.

A conjugated polymer of poly(fluorene-co-benzothiadiazole) (PFBT) was modified by a soft segment of poly(dimethylsiloxane) (PDMS) to yield a copolymer via dynamic imine bonds. The copolymer was casted as a free-standing film, which was intrinsically flexible, stretchable, and showed tunable shape memory, healable and degradable effects.

In order to increase the operation safety of ship nuclear power platform. A typical butterfly valve with nuclear safety class 2 of ship power plant is studied in this paper. Numerical analysis on shock resistance safety of butterfly valve is conducted by three-dimensional finite element method. Firstly, the load type under working condition and the stress evaluation criteria of valve safety analysis are determined based on national standards and ASME standards. Secondly, the finite element model of butterfly valve is constructed and the equivalent stress distribution of butterfly valve is obtained under static loads and constraint conditions. Moreover, the butterfly valve natural frequencies and vibration shapes are obtained by modal analysis under inspection working condition. Furthermore, the butterfly valve stress distributions on three coordinate directions are analyzed by shock response spectrum analysis according to the modal analysis results. Lastly, the total stress distribution of butterfly valve is obtained by superposition procedure. And the butterfly valve structure shock resistance safety is checked based on the stress evaluation criteria.

The Brayton cycle with supercritical carbon (S-CO2) as working medium is one of the most promising new nuclear power systems. Turbine is the key device during the working process in the Brayton power cycle. The turbine structural presents small size and extremely high rotational speed for the special physical properties of S-CO2, which increase the difficulty for the structural design and strength safety significantly. According to the aerodynamic design and optimization results of 200 kW S-CO2 radial inflow turbine, this paper proposes a detail structural design and analysis method for turbine impeller. Based on the three-dimensional blade profile data and meridional planes data, key structural design parameters are chosen and the parametric geometry model is established by CAD tools. On this basis, numerical simulation models of turbine are established to analyze the structural strength in detail. Then the influence of parameters on the turbine impeller strength is studied by a series of finite element numerical procedures. The influence mechanisms of key structural design parameters on impeller strength are discussed. Moreover, the final model of turbine impeller is obtained by parameter comparison and selection. The results show that for the initial model, the maximum von-Mises equivalent stress is 400.10 MPa, the maximum radial deformation is 0.0333 mm and the maximum axial deformation is 0.0770 mm. For the final model, the maximum von-Mises equivalent stress is 294.26 MPa, the maximum radial deformation is 0.0279 mm and the maximum axial deformation is 0.0769 mm. The maximum von-Mises equivalent stress and maximum radial deformation of structural decreases 26.45 % and 16.22 % respectively compared with the initial model. As a result, the impeller structural strength safety margin is obviously improved by the parameter analysis.

Steam submerged jetting is an important process in depressurization tank and condenser deaerator tank of nuclear power plant. As the steam contact the liquid water directly, some complicated behaviors such as strong turbulence and phase transition would happens. Especially when the sub-cooling degree is low, the condensation may cause vigorous pressure pulsation and radiation noise, which not only causes noise damage to workers but also affect the safety of the heat exchanger tubes bundle because of vibration transmission. An experiment is proposed to study the complex evolutionary behavior and vibration and noise characteristics of gas-water two-phase flow. The experimental results show that in the case of low subcooling, the mass flow rate of steam has a great influence on gas plume, and, as the mass flow rate increases, the main contribution frequency of noise is gradually increasing from low frequency to high frequency. The researches in this paper can provide the technical basis for the design of the deoxygenation system of condenser in onshore and ship nuclear power plant.

An improved nonlinear tracking differentiator(INTD) with limited control variable is proposed in this paper. Compared with the existing high speed nonlinear tracking differentiators(HSTD), INTD preserves the stability of HSTDs at the target state and their rapidity. In particular, the HSTD's problem of poor anti-interference ability and narrow application range is solved by INTD. This paper analyzes the tracking performance of INTD with different threshold coefficient of control variable and processing different step signals under the same threshold coefficient. It is verified that HSTD needs a proper limit for control variable. INTD is applied to process the magnetic phase signal of maglev train position and speed detection system, the result shows that this improved nonlinear tracking differentiator can well track and filtering phase angle signal.

Three dibenzothiophene-S,S-dioxide-based alternating copolymers were synthesized by facile Suzuki polymerization for visible light-responsive hydrogen production from water (> 420 nm). Without addition of any cocatalyst, FluPh2-SO showed a photocatalytic efficiency of 3.48 mmol h-1 g-1 , while a larger hydrogen evolution rate (HER) of 4.74 mmol h-1 g-1 was achieved for Py-SO, which was ascribed to the improved coplanarity of the polymer that facilitated both intermolecular packing and charge transport. To minimize the possible steric hindrance of FluPh2-SO by replacing 9,9'-diphenylfluorene with fluorene, Flu-SO exhibited a more red-shifted absorption than FluPh2-SO and yielded the highest HER of 5.04 mmol h-1 g-1 . This work highlights the potential of dibenzothiophene-S,S-dioxide as a versatile building block and the rational design strategy for achieving high photocatalytic efficiency. NRF (Natl Research Foundation, S’pore) ASTAR (Agency for Sci., Tech. and Research, S’pore) MOE (Min. of Education, S’pore)

A filtering algorithm and direction identification method are presented for the positioning system of the mid-speed maglev train. Considering the special structure of the mid-speed maglev train, the ground position estimation method is adopted for its traction system. As the train is running, the induction loop-cable receives the signal sent by the on-board antenna to detect the position and direction of the train. But the height of the on-board antenna relative to the loop-cable is highly vulnerable to the change of the suspension height and the magnetic field produced by the traction during traveling, which may lead to amplitude fluctuation of the received signal. Consequently, the position estimation may be inaccurate. Therefore, a discrete second-order nonlinear trackdifferentiator is proposed based on the boundary characteristic curves, and the new differentiator could also extract the running direction of the train for the traction system. The experimental results show that the tracking differentiator can effectively filter out the signal interference and can provide accurate direction signal.

A novel D-A conjugated polymer backbone containing silole and 9-octyl-9H-carbazole units was synthesized via Sonogashira reaction. This silole-containing polymer (SCP) was further used to prepare SCP dots with a nanoprecipitation method, which showed an electrochemiluminescence (ECL) emission at relatively low potential in aqueous solution. The strong anodic ECL emission could be observed at +0.4 V (vs Ag/AgCl) with a peak value at +0.78 V in the presence of tri-n-propylamine (TPrA) as a co-reactant, which came from the band gap emission of the excited SCP dots. The ECL emission could be quenched via resonance energy transfer from the excited SCP dots to an acceptor. Thus, a low-potential anodic ECL sensing strategy was proposed for ECL detection of the acceptor-related analytes. Using dopamine as the analyte, whose electro-oxidation product could act as the energy acceptor to quench the ECL emission of SCP dots, the ECL detection method showed a detection limit of 50 nM and high anti-interference ability. This work demonstrates an example of polymer dots as an ECL emitter and its potential application in ECL detection methodology.

Flow chemistry has attracted significant interest in pharmaceutical development, where substantial efforts have been directed toward the design of continuous processes. Here, we report a total synthesis of atropine in flow that features an unusual hydroxymethylation and separation of several byproducts with high structural similarity to atropine. Using a combination of careful pH control in three sequential liquid-liquid extractions and a functionalized resin, atropine is delivered by the flow system with >98% purity., United States. Defense Advanced Research Projects Agency (DARPA N66001-11-C-4147)

The paper is mainly focused on the induced circular dichroism (ICD) based on central-to-axial chirality transfer for direct chiral recognition and ee value detection of 1,2-diaminocyclohexane (1,2-DACH) enantiomers. A novel achiral polymer sensor with potential axial chirality feature is designed and synthesized. This conjugated polymer incorporating biphenol moiety can bind chiral 1,2-DACH substrates via intramolecular hydrogen-bonding interactions, which could result in the detectable exciton-coupled circular dichroism (CD) spectrum due to the chirality transfer from an enantiopure building block to a dynamically racemic 1,1′-biphenyl-2,2′-diol moiety in the polymer chain backbone. The linear regression analysis of ICD sensing shows an excellent agreement between CD intensity and concentration of chiral 1,2-DACH, which indicates this biphenol-based achiral polymer can be used as a chiral sensor for direct recognition and ee value detection of 1,2-DACH enantiomers by using ICD spectra of achiral polymer sensor.