BP神经网络权值初始值与收敛性问题研究

BP神经网络的收敛性问题是一直受到广泛关注的问题。本文针对BP网络在运算过程中陷入局部最小区，收敛速度慢的问题，从BP算法的原理出发，讨论了权值初始值对网络训练速度的强烈影响（仿真结果证明了这一点），并提出了解决方法。     

Characterization of a Thermostable and Surfactant-Tolerant Chondroitinase B from a Marine Bacterium Microbulbifer sp. ALW1

Chondroitinase plays an important role in structural and functional studies of chondroitin sulfate (CS). In this study, a new member of chondroitinase B of PL6 family, namely ChSase B6, was cloned from marine bacterium Microbulbifer sp. ALW1 and subjected to enzymatic and structural characterization. The recombinant ChSase B6 showed optimum activity at 40 °C and pH 8.0, with enzyme kinetic parameters of K_m and V_max against chondroitin sulfate B (CSB) to be 7.85 µg/mL and 1.21 U/mg, respectively. ChSase B6 demonstrated thermostability under 60 °C for 2 h with about 50% residual activity and good pH stability under 4.0–10.0 for 1 h with above 60% residual activity. In addition, ChSase B6 displayed excellent stability against the surfactants including Tween-20, Tween-80, Trion X-100, and CTAB. The degradation products of ChSase B6-treated CSB exhibited improved antioxidant ability as a hydroxyl radical scavenger. Structural analysis and site-directed mutagenesis suggested that the conserved residues Lys248 and Arg269 were important for the activity of ChSase B6. Characterization, structure, and molecular dynamics simulation of ChSase B6 provided a guide for further tailoring for its industrial application for chondroitin sulfate bioresource development.     

Ambient flash sintering of reduced graphene oxide/zirconia composites:Role of reduced graphene oxide

Fabrication of graphene/ceramic composites commonly requires a high-temperature sintering step with long times as well as a vacuum or inert atmosphere,which not only results in property degradation but also significant equipment complexity and manufacturing costs.In this work,the ambient flash sintering behavior of reduced graphene oxide/3 mol% yttria-stabilized ZrO₂(rGO/3 YSZ) composites utilizing rGO as both a composite component and a conductive additive is reported.When the sintering condition is carefully optimized,a dense and conductive composite can be achieved at room temperature and in the air within 20 s.The role of the rGO in the FS of the rGO/3 YSZ composites is elucidated,especially with the assistance of a separate investigation on the thermal runaway behavior of the rGO.The work suggests a promising fabrication route for rGO/ceramic composites where the vacuum and furnace are not needed,which is of interest in terms of simplifying the fabrication equipment for energy and cost savings.     

Differences in lithospheric structures between two sides of Taihang Mountain obtained from the Zhucheng-Yichuan deep seismic sounding profile

A 2-D model of lithospheric velocity structures in the southern part of the North China Craton was obtained using data from the Zhucheng-Yichuan deep seismic sounding profile.Results show that there are great differences in lithospheric structures between two sides of Taihang Mountain.In the eastern region,the lithosphere is thinner,with a thickness of about 70-80 km,while in the western region,the thickness is 85-120 km.There is a jump of the lithospheric thickness across Taihang Mountain gravity anomaly b...     

天线间耦合度自动测试系统设计

多天线系统的电磁兼容性很大程度上取决于系统内收发天线间的射频能量耦合。天线间耦合度是评估系统级电磁兼容性的重要指标。针对目前传统手工测试的种种弊端,设计了基于射频开关自动切换的天线间耦合度自动测试系统,详细阐述了系统硬件构成、软件的设计思路以及具体的测试流程,使用LabVIEW编写软件控制收发天线对的自动切换,实现自动测量,具有测量误差小,测量便捷等优点。     

政府在落实高校办学自主权中的作用刍议

高校办学离不开政府的管理,政府在落实高校办学自主权中发挥着重要的作用。目前,政府对高校的管理内容过细、方式过于直接。政府应通过法律、经济、计划、行政、信息等手段对高校自主办学进行宏观的、间接的、服务型的管理。     

Study on Thermal Deformation Behavior and Properties of Vacuum Hot-press Sintered W(50)/Cu-Al_2O_3 Composite

In this work, the tungsten particulate reinforced Al2O3 dispersion strengthened copper base composites were successfully fabricated by using a vacuum hot-press sintering method. With the test temperature varying from 650 to 950 ℃ and the strain rate varying from 0.01 to 5 s-1, the W(50)/Cu-Al2O3 composites were isothermally compressed on a Gleeble-1500D thermal simulator. The true stress-strain curves of the W(50)/Cu-Al2O3 under different test conditions were obtained. The dynamic recrystallization of the W...     

结肠镜检查者肠道准备无效的原因分析及应对措施

目的:探讨结肠镜检查者肠道准备无效的原因及应对措施.方法:有经验的肠镜检查医师根据肠道清洁效果评价指标进行评价.结果:1313例检查者中有49例肠道准备无效.结论:服药方法、疾病因素、年龄、心理状态、肠镜检查次数等都对肠道准备效果产生了影响.     

临淮岗洪水控制工程管理通过水利部考核的做法

本文简要阐述临淮岗工程水闸处在创建水利部验收水管单位过程中做法,在此基础上总结成功申报经验,供有关单位参考.     

Degenerate problems of optimal control. II

The paper is the second part of the review of the results obtained by the special theory of the degenerate problems of optimal control and its applications, including the newest ones. Consideration was given to the methods based on the rearrangement of the degenerate problems in the smaller-order regular derivative problems, the main types of solutions of the derivative problems, and the issues of their realization as the generalized solutions of the original problems. The generalized conditions for their optimality were derived. Examples, both methodological and applied, were presented to demonstrate the efficiency of these methods.