摘要：To promote the visualisation and informatisation of the construction process of precast foamed lightweight concrete wallboards(PFLCWs),from the analysis of the construction requirements of PFLCWs,three key construction technologies based on building information modelling(BIM),namely,parameterised modelling for the PFLCW layout design,drawing generation to draw the PFLCW layout and quantity statistics for extracting PFLCW quantities,are ***,a reinforced concrete(RC)frame infilled with PFLCW is considered the test model to verify the feasibility of the aforementioned *** results show that PFLCW layout design can be accomplished rapidly and visually using parameterised modelling *** PFLCW layout diagram can be generated directly using drawing generation *** proposed quantity statistics technology enables the automatic export of PFLCW bills of *** built parameterised model helps construction workers rapidly and intuitively understand the specific layout details of ***,the generated layout drawing and the bills of quantities based on the parameterised model can guide the production and on-site installation of *** research conclusions can serve as a practical guide and technical support for PFLCW engineering applications.

摘要：Roof pre-splitting is an effective method to control the roof with potential rock burst *** this study,three-point bending tests were carried out by using fine sandstone specimens with different pre-cracked lengths as test objects,and digital speckle correlation method(DSCM)and acoustic emission(AE)technology were used to track the entire process of crack *** effect of pre-cracks on the fracture of rock beams was evaluated,and the mechanical mechanism of the rock beam fracture process was *** rock beam pre-splitting design method was developed,and the application effect of the method was proved by the microseismic monitoring data obtained from the 10303 working face of Jining No.2 coal mine in *** results show that the loading time history curve of pre-cracked beams exhibits obvious residual *** with the intact rock beam,the tensile strength,and maximum tensile strain of 35 mm pre-cracked rock beam are decreased by 32.4% and 33.1%,respectively and the acoustic emission b value is increased by 30.2%.According to the pre-splitting design method of rock beam,the maximum and average microseismic energy of the 10303 working face after pre-splitting construction are reduced by 25.6% and 6.4%,respectively,with excellent prevention and control effect of thick roof.

摘要：Shape memory polymers(SMPs)are a promising class of materials for biomedical applications due to their favorable mechanical properties,fast response,and good ***,it is difficult to achieve controllable sequential shape change for most SMPs due to their high deformation temperature and the simplex deformation ***,shape memory composites based on polylactic acid(PLA)matrix and semi-crystalline linear polymer polycaprolactone(PCL)are fabricated using 4D printing *** with pure PLA,with the rise of PCL content,the 4D-printed PLA/PCL composites show decreased glass transition temperature(Tg)from 67.2 to 55.2°*** the precise control of the deformation condition,controllable sequential deformation with an outstanding shape memory effect can be achieved for the PLA/PCL shape memory *** response time of shape recovery is less than 1.2 s,and the shape fixation/recov-ery rates are above 92%.In order to simulate sequential petal opening and sequential drug releasing effects,a double-layer bionic flower and a drug release device,respectively,are presented by assembling PLA/PCL samples with different PLA/PCL *** results indicate the potential applications of 4D-printed PLA/PCL composites in the field of bio-inspired robotics and biomedical devices.

摘要：In the present study, we designed and synthesized a series of 1-substituted-β-carboline derivatives through modification of position-l, 2 and 9 of β-carboline nucleus in order to discover novel leading compounds with better antitumor activities and less toxicity. Their structures were confirmed by 1H NMR, 13C NMR, MS, IR and elemental analyses. All the target compounds were tested for cytotoxic activity against six cancer cell lines, including Bel-7402, HepG2, A549, A375, 786-0 and HT-29 by methyl thiazolyl tetrazolium （MTT） method. Studies of structure-activity relationships indicated that the effects of substituents in position- 1 on cytotoxic activities were in an order as follows： 2-thienyl 〉2-chlorophenyl 〉4-chlorophenyl 〉benzyl group.

摘要：The idea that single metal atoms dispersed on a solid support can act as an efficient heterogeneous catalyst was raised in2011when single Pt atoms on an FeOx surface were reported to be active for CO oxidation and preferential oxidation of CO in *** last six years have witnessed tremendous progress in the field of single‐atom *** we introduce the major achievements on this topic *** particular aspects of single‐atom catalysis are discussed in depth,including new approaches in single‐atom catalyst(SAC)synthesis,stable gold SACs for various reactions,the high selectivity of Pt and Pd SACs in hydrogenation,and the superior performance of non‐noble metal SACs in *** accomplishments will encourage more efforts by researchers to achieve the controllable fabrication of SACs and explore their potential applications.

摘要：A macro-micro dual-drive positioning system showing good potential for high acceleration and high precision positioning required in IC packaging applications is devised in this paper. The dual-drive positioning stage uses a VCM (voice coil motor) driven macro positioning stage and a PZT piezo-electric driven micro positioning stage. The coupling characteristics of the system are analyzed to produce a control structure with a micro positioning stage that can dynamically compensate for the positioning error produced by the macro positioning stage. Models of the two positioning stages are described. The models cover both the mechanism and the actuator. For the macro positioning stage, friction characteristics are taken into account, and a controller with an LQG (linear-quadratic-Gaussian) control algorithm combining a feed-forward compensation algorithm is derived. A PID controller is used to control the micro positioning stage. Detailed designs are derived for the proposed approach, and the performance is validated by simulation.

摘要：The current literature lacks uniform calculation methods for following trajectory control for autonomous vehicles,including the calculation of errors,determination of tracking points,and design of feedforward ***,a complete calculation method is proposed to address this ***,a control equation in the form of an error is obtained according to the dynamic equation of the vehicle coordinate system and the trajectory following ***,the deviation of the vehicle state is obtained according to the current vehicle s state and the following control ***,a linear quadratic regulator(LQR)controller with feedforward control is designed according to the characteristics of the dynamic *** the proposed LQR,the simulation of computational time,anti-interference,and reliability analysis of the trajectory following control is performed by programming using *** simulation outcomes are then compared with the experimental results from the *** comparison indicates that the proposed complete calculation method is effective,reliable,and capable of achieving real-time and anti-interference following control *** simulation results with or without feedforward control show that the steady-state error is eliminated and that good control performance is obtained by introducing feedforward control.

摘要：Flexible wearable sensors with excellent electric response and self-powered capability have become an appealing hotspot for personal healthcare and human-machine ***,based on triboelectric nanogenerator(TENG),a flexible self-powered tactile sensor composed of micro-frustum-arrays-structured polydimethylsiloxane(PDMS)film/copper(Cu)electrodes,and poly(vinylidenefluoride-trifluoroethylene)(P(VDF-TrFE))nanofibers has been *** TENG-based self-powered tactile sensor can generate electrical signals through the contact-separation process of two triboelectric layers under external mechanical *** to the uniform and controllable micro-frustum-arrays structure fabricated by micro-electro-mechanical system(MEMS)process and the P(VDF-TrFE)nanofibers fabricated by electrostatic spinning,the flexible PDMS-based sensor presents high sensitivity of 2.97 V kPa^-1,stability of 40,000 cycles(no significant decay),response time of 60 ms at 1 Hz,low detection pressure of a water drop(~4 Pa,35 mg)and good linearity of 0.99231 in low pressure *** the PDMS film presents ultra-flexibility and excellent-biocompatibility,the sensor can be comfortably attached on human ***,the tactile sensor can recognize various types of human body movements by the corresponding electrical ***,the as-prepared TENGs are potential on the prospects of gesture detection,health assessment,human-machine interfaces and so on.

摘要：Information storage and corresponding encryption/decryption are highly important owing to the prevalence of counterfeit activities and information leakage in the current age. Herein, we propose a novel method to store information via controllable ionoprinting onto fluorescent hydrogel for hierarchical and multi-dimensional *** incorporating pyrene moieties and carboxylic groups into polymeric hydrogel network, fluorescence changing and controllable shape deformation behaviors could be achieved and integrated by ionoprinting of Fe3+ions. The diffusion of Fe^3+ions into fluorescent hydrogel can quench the fluorescence of pyrene moieties, and chelate with carboxylic groups to generate anisotropic structures for shape deformation simultaneously. Thus, fluorescence quenching-based 2D information and actuation-based 3D information could be hierarchically decrypted when exposed to UV light and being put into water, respectively. Importantly, the stored information could be erased by replacing Fe^3+with H^+, which allows the fluorescent hydrogel as a recyclable information storage material. This work may provide new insights in designing and fabricating novel soft devices for hierarchical and multidimensional information encryption, against the rising problems of counterfeiting and confidential information disclosure.

摘要：针对收割过程中通常只在开机时设置一次作业参数,不能经常停机观察籽粒的清洁度进而随时调节作业参数这一问题,需要研制一种能够自动获取联合收获机作业过程中含杂率数据的装置。但是,迄今为止,在收获过程中监测籽粒含杂率的研究还处于探索阶段。针对以上问题,结合联合收获机作业过程中谷物的流变特性,该文设计了一种谷物含杂率传感器,通过电磁铁(弹簧)控制挡板的伸出(复位),以使采样盒可视玻璃窗口前聚集(卸载)谷物,通过采样盒内CMOS相机获取数字图像,应用数字图像处理技术获得含杂率。依据图像直方图优化LED光源的照射及安装方法以获取高质量图像,分析了电磁铁提供的拉力和弹簧提供的推力、采样盒入口尺寸,采用全局阈值迭代算法,使用三个迭代步提取稻谷、茎秆和细柄连通域,计算每个连通域的像素,最终从形态上识别了谷物和杂质,同时测量稻谷千粒质量、茎秆面密度和细柄线密度,建立了计算谷物杂质质量的数学模型。结果表明:在采样盒内两侧各安装2个LED,间接照射视窗时获取的图像质量较好,有效避免了图像强度直方图中出现的峰值;额定拉力为60 N的电磁铁可以提供足够的拉力;采用线径为1 mm的弹簧能提供足够的推力,由于在收割过程中出现的短秸秆和细柄的长度在10 mm到30 mm之间,因此采样盒的设计高度为95.7 mm,宽度为76.5 mm,入口宽度为31.9 mm,视窗长度为57.1 mm,宽度为57.4 mm,如此稻谷、秸秆和细柄可以顺利流入采样盒,并且在视窗中可以看到约200粒谷粒。在不同含杂率下进行了籽粒含杂率传感器监测精度的台架试验,结果表明:该装置监测的籽粒含杂率与人工获得的籽粒含杂率具有一致的变化趋势,能够监测在0～2.88%范围内的籽粒含杂率。为了满足田间作业监测需求,同时设计了采样盒的防水防尘罩,为相机提供一个稳定抓取图像的工作环境。于2017年11月17日,在苏州九里湖进行了不同喂入量下含杂率监测试验,试验使用Yamma4LZ2.5联合收割机,结果表明,田间试验的相对误差在9.44%和19.67%之间。该研究可为田间收获过程中自动获取谷物含杂率提供参考。