Flexible,self-cleaning,and high-performance ceramic nanofiber-based moist-electric generator enabled by interfacial engineering

Due to their long-term stability, even under extreme conditions, oxide ceramics have attracted significant attention in emerging fields like moist-electric generation However, the inherent brittleness and low voltage output of oxide ceramic-based moist-electric generators (MEGs) limit their applications in wearable electronics. Herein, a facile strategy involving the combination of sol-gel electrospinning and calcination is used to fabricate flexible and freestanding TiO₂/ZrO₂ (TZ) composite nanofiber-based MEGs. The excellent flexibility of the TZ nanofiber membranes can be attributed to the suppression of their crystal structure transformation, dispersion of stress concentration, and reduction of crack propagation via interfacial engineering The porous structure of the electrospun nanofiber membrane features an abundance of charged narrow channels for the diffusion of water molecules and generates a streaming potential: The optimal voltage output reached ～0.8 V, which is the highest value reported for an oxide ceramic-based MEG. Furthermore, the as-fabricated nanofiber-based MEG exhibits good self-cleaning capability to degrade organic pollutants under ultraviolet irradiation. By integrating mechanical flexibility, high performance, and a self-cleaning effect, this work presents a new idea for exploring diverse, efficient, and wearable oxide ceramic-based MEGs.

     

银洞子多金属矿可持续发展研究

根据银洞子多金属矿矿区的自然资源情况和矿区所具有的区位优势,对该矿区可持续发展进行了研究,结果表明:矿区的找矿前景广阔;在现有勘探成果及采选设施和金属市场条件下,可基本实现矿山的初期积累和滚动;矿床赋有的矿石其综合利用价值较高,矿区又具有很好的区位优势,使得矿山完全有可能建设成1座中型以上的多金属加工矿山;丰富的多金属资源加上优质大理岩和水电,为矿山走上循环经济发展的道路奠定了坚实的基础。     

Dynamics modeling and simulation of mechanism with joint clearance

The existence of clearance in the joints of mechanisms system is inevitable.The movements of the real mechanism are deflection from the ideal mechanism due to the clearances and the motion accuracy is decreased.The effects of the hinge clearance on the crank and rocker mechanism system are studied.The system dynamics equation with clearance is presented.The contact dynamics model is established using the nonlinear equivalent spring-damp model and the friction effect is considered by using Coulomb friction model.Then the models are incorporated into ADAMS,and based on the model,large numbers numeric simulations are made.The regularity of contact forces in clearance are studied in detail.And the effects of clearance size,clearance friction on the mechanism dynamics characteristic are analyzed.The simulation results can predict the effects of clearance on the mechanism dynamics characteristic preferably.     

On orbit estimation of spacecraft dynamic property

Mass property of spacecraft needs to be estimated in certain circumstances.Based on the measurement of single point acceleration,angular acceleration and angular velocity,a discrete Kalman Filter(KF) based estimation method is developed to extract the inertia matrix and mass center.The simulation results show that the method can be used for continues online estimation without propellant consumption.Stability condition for the filter is given at last.     

某采用反吊膜结构封闭的大型生物处理池的结构设计

本文通过北京经济技术开发区东区污水厂生物处理池的工程实例,分析了反吊膜封闭的大型处理池在结构设计中遇到的一些问题,并提出了一些观点。     

Transferring deep neural networks for the differentiation of mammographic breast lesions

Machine learning can help differentiating benign and malignant lesions seen on mammographic images. Conventional models require handcrafting features for lesion representation. Due to insufficient medical instances, the performance of convolutional neural networks(CNNs) can be further increased. This study makes use of transfer learning for mammographic breast lesion diagnosis and deep neural network(DNN) models pre-trained with large-scale natural images are employed. The diagnosis performance is evaluated with the prediction accuracy(ACC) and the area under the curve(AUC) on average. A histologically verified database is analyzed which contains 406 lesions(230 benign and 176 malignant). Involved models include transferred DNNs(GoogLeNet and AlexNet), shallow CNNs(CNN2 and CNN3) that are fully trained with medical instances and boosted by support vector machine(SVM), and two conventional methods which combine handcrafted features and SVM for lesion diagnosis. Experimental results indicate that GoogLeNet achieves the best performance(ACC=0.81, AUC=0.88), followed by AlexNet(ACC=0.79, AUC=0.83) and CNN3(ACC=0.73, AUC=0.82). Knowledge transfer can improve the mammographic breast cancer diagnosis, while its wide application still requires further verification in medical imaging domain.     

太阳能-土壤源热泵系统在华北地区应用的模拟研究

本文针对我国华北地区冬季寒冷需要供暖、夏季炎热需要空调,但是全年冷热负荷很不平衡的气候特点,提出太阳能-土壤源热泵系统的联合运行方案。以北京地区1栋别墅建筑为研究对象,在其全年动态负荷的基础上,对系统进行设计计算,并对全年运行工况模拟分析,得到系统在全年运行过程中主要参数的变化情况,为该系统在华北地区的应用作初步性研究,为以后该系统的设计及工程应用提供参考。     

高速铁路精调测量后方交会精密数据处理

高速铁路对无喳轨道平顺性的高要求,而轨道精调测量直接影响到轨道的平顺性.通过对精调精密测量数据的处理,对后方交会得到的数据采用Baarda法进行数据探测,并进行粗差剔除从而达到提高精度的要求,经过验证能够达到提高轨道精调精度的目的.     

基于H.264的可伸缩编码比特流流切换方案

H.264／AVC支持同步预测（SP）帧,允许不同质量比特流之间的高效切换;MPEG-4支持精细颗粒可伸缩（FGS）编码。提出一种将两者融合在一起的解决方案,使得传输的比特流既能适应因特网或无线网传输带宽的大范围波动,又能灵活适应小范围的带宽变化。仿真实验结果表明：该方案的亮度Y峰值信噪比（Y-PSNR）比FGS平均好0．47dB,比流切换（SS）方法平均好0．23dB。     

Composite membranes based on a novel benzimidazole grafted PEEK and SPEEK for fuel cells

Poly(ether ether ketone) (PEEK) and sulfonated poly(ether ether ketone) (SPEEK, IEC = 2.07 mequiv.g⁻¹) have been synthesized via nucleophilic aromatic substitution reaction. Bromomethylated poly(ether ether ketone) (PEEK-Br) is then prepared and reacted with 2-benzimidazolethiol to obtain the benzimidazole grafted poly(ether ether ketone) (PEEK-BI). The structures of PEEK-Br and PEEK-BI are characterized by ¹H NMR spectra. Composite membranes based on SPEEK and PEEK-BI are prepared and their properties used for fuel cells are studied in detail. The results show that the composite membranes exhibit greatly improved mechanical properties as well as reduced water uptake and methanol permeability compared with the pristine SPEEK membrane. The increased oxidative stability and selectivity indicate that the composite membranes are promising to be used as proton exchange membranes.