摘要：Porous g-C_(3)N_(4)nanosheets(PCN)were prepared by the nickel-assisted one-step thermal polymerization ***(H2)which was produced by the reaction between nickel(Ni)foam and ammonia(NH3)defined the structure and properties of *** the formation of PCN,the participation of H2 not only enhanced the spacing between layers but also boosted the specific surface area that more active sites were ***,H2 promoted pores formation in the nanosheets,which was beneficial to the transfer of photons through lamellar structure and improved the absorption efficiency of visible ***,the obtained PCN possessed better Cr(Ⅵ)photocatalytic reduction efficiency than pure g-C_(3)N_(4).The reaction rate constant(k)of PCN(0.013 min-1)was approximately twice that of bare g-C_(3)N_(4)(0.007 min-1).Furthermore,the effects of original pH and concentration of Cr(Ⅵ)-containing solution on re moval efficiency of Cr(Ⅵ)were explored.A possible photocatalytic mecha nism was proposed based on the experiments of radical scavengers and photoelectrochemical characterizations.

摘要：We developed a new one step approach to synthesize g-C3N4 nano-sheets by direct thermal pyrolysis process of urea in NH3 atmosphere. For the first time, the influence of the preparation gas atmosphere on the composition, crystalline and polymerization degree, and the activity of the g-C3N4 synthesized from thermal condensation of urea was investigated. Impressively, the g-C3N4 nano-sheets obtained under NH3 gas atmosphere exhibited much superi- or photo-catalytic activities to the prepared g-C3N4 in air or N2, and the rate of the g-C3N4-NH3 was about 5 times higher than that on g-C3N4-N2 sample. The detailed characterization analysis revealed that NH3 thermal pyrolysis atmosphere contributed to the polymerization degree and the formation of the layer with a more regular structure due to the efficiently extending of the conjugated π-conjugative system, which was favorable to the transfer of the photo-induced charge carriers. Furthermore, we studied in depth the structure-performance relationship in the sys- tem, and it was found that the synergistic effect of the larger surface area, the adjusted band energy structure and the well crystallization may be conductive to the higher separation of the electron-hole pair, thus leading to the won- derful performance for the g-C3N4-NH3. Notably, the method has the merits of low cost, scalable production and environmental friendliness.

摘要：定向电荷转移是调控光生载流子分离动力学的一种极具吸引力的策略。本文通过在SnNb_(2)O_(6)纳米片上原位生长C_(3)N_(5)纳米棒,设计一种具有强内建电场(IEF)和偶极场(DF)的新型2D/1D SnNb_(2)O_(6)/富氮C_(3)N_(5)S型异质结。通过构筑S型异质结,在界面处产生IEF,促进电荷从SnNb_(2)O_(6)向C_(3)N_(5)的定向迁移。与此同时,C_(3)N_(5)中的DF提供一种驱动力,将光生电子定向转移至活性位点。通过IEF和DF的协同效应,SnNb_(2)O_(6)/C_(3)N_(5)异质结实现了快速的定向电子转移,从而显著提高了电荷分离效率。研究结果表明,SnNb_(2)O_(6)/C_(3)N_(5)异质结的最佳产氢速率高达1090.0μmol·g^(-1)·h^(-1)(反应过程中持续释放H2气泡),分别是SnNb_(2)O_(6)和C_(3)N_(5)的38.8和10.7倍。此外,SnNb_(2)O_(6)/C_(3)N_(5)异质结在去除罗丹明B、四环素和Cr(Ⅵ)方面也表现出优异的光催化性能。通过电子顺磁共振(EPR)、时间分辨光致发光光谱(TPRL)和密度泛函理论(DFT)计算,本文系统探讨了SnNb_(2)O_(6)/C_(3)N_(5)异质结的定向电荷转移机制。这项研究为开发高效异质结光催化剂提供了一种可行的方法。

摘要：市政排水与水利排涝作为城市两级排涝系统,因两者的管理部门不同,其设计标准及行业规范也有所区别,导致市政排水与水利排涝在计算设计流量上存在不匹配问题。为了研究市政排水与水利排涝两级标准之间的对应关系,以上饶市区域内实际工程为案例,采用2种方法分别计算设计流量,并对比分析其计算结果,可为市政及水利规划建设中两级排涝标准衔接和统一提供参考。

摘要：In order to design the scale model in a wide frequency range,a method based on the reflective loss is proposed according to the high-frequency approximation algorithm,and an example of designing the scale model of a plate-shaped absorber is given in this *** the example,the frequency of the full-size measurement ranges from 2.0 GHz to 2.4 GHz,the thickness of the full-size absorber is 1 mm and the scale ratio is 1/5.A two-layer scale absorber is obtained by the proposed *** thickness values of the bottom and top layer are 0.4 mm and 0.5 mm,***,the scattering properties of a plate model and an SLICY model are studied by FEKO to verify the effectiveness of the designed scale *** with the corresponding values from the theoretical scale model,the average values of the absolute deviations in 10 GHz～12 GHz are 0.53 d Bm^2,0.65 d Bm^2,0.76 d Bm^2 for the plate model and 0.20 d Bm^2,0.95 d Bm^2,0.77 d Bm^2 for the SLICY model while the incident angles are 0°,30°,and 60°,*** deviations fall within the Radar cross section（RCS） measurement ***,the work in this paper has important theoretical and practical significance.

摘要：针对广告编辑手法多样导致的广告单元分割较难的问题,提出了融合音频和文本信息的广告单元分割算法。对广告中的音频数据进行高斯混合模型建模,基于分割熵实现音频跳变点检测。沿着时间轴,结合音频跳变点和基于小波变换和支持向量机的文本检测实现对广告单元切换点的第一轮检测。基于时间间隔进行广告单元切换点的第二轮检测。实验证实该算法对广告单元中音频跳变点检测的查全率和查准率高于80%,对广告单元分割的查全率和查准率约为70%。

摘要：有机朗肯循环(Organic Rankine Cycle,ORC)在可再生能源和工业余热领域都有着良好的应用前景,特别是超临界ORC系统目前得到广泛关注。工质的热稳定性和材料相容性是工质的重要物性,对系统设计有很大的影响。本文以正戊烷为例,对热稳定性和材料相容性对超临界ORC系统设计的影响进行研究。提出了一种冷凝器改造装置方案,并建立ORC系统仿真模型对其改善效果进行验证;计算结果表明本文提出的改造方案可以明显改善正戊烷热分解带来的负面影响。同时对中高温工况下正戊烷的材料相容性进行实验研究。实验结果表明,304不锈钢相对铜材料有更优的相容性,从材料相容性角度来说是更合适的蒸发器材料。三元乙丙橡胶(EPDM)被证明会吸收正戊烷,因此不能用于正戊烷超临界ORC系统中;聚四氟乙烯(PTFE)相比氟橡胶(FKM)有更优的相容性,从材料相容性角度来说是更合适的膨胀机出口密封材料。

摘要：双级旋流器是航空发动机燃烧室头部产生回流区所采用的主要形式,研究主要考察第2级径向旋流器的旋流数对点火与燃烧稳定性能的影响,数值模拟结果能够较好地匹配第2级径向旋流器设计参数.试验研究表明:第2级径向旋流器旋流数的改变对燃烧室点火性能无影响;但减小该旋流数会对贫油熄火性能产生明显地改善,旋流卷吸效果会影响回流区火焰稳定.减小第2级径向旋流器旋流数,使下游卷吸量增加,回流区流动与火焰匹配更好,更有利于燃烧稳定性的提高.

摘要：This paper introduces the approach types of agricultural technology promotion we can choose in the process of new countryside construction, and there are mainly 6 types, namely government-domination-oriented approach, market-development-oriented approach, university (scientific research institution)-education-oriented approach, farmers' participation-oriented approach, direct-training-oriented approach and individual-service-oriented approach, including 20 models. The problems existing in the grass-root agricultural technology promotion in the process of new village construction are analyzed as follows: the awareness of innovation is not strong; scientific research, education, and promotion are disjointed; the construction of specific work system lags behind; the structure of promotion team is irrational, and the quality of promotion personnel is yet to be promoted; the cultural quality of farmers is low, and the cooperative organizations are not sound; the working conditions are poor, and the basic security is inadequate; the investment channel is simple and the supply amount is badly short; the methods of agricultural technology promotion do not adapt to the requirements of new situation. According to the characteristics and internal requirements of grass-root agricultural technology promotion, we creatively design an overall working model, and put forward new measures from objective of grass-root agricultural technology promotion, service object, service content, organization work and scope, method, role of agricultural technology personnel and so on.

摘要：本文研究柔性机械臂的轨迹跟踪和振动抑制问题.首先,利用Lagrange法和假设模态法建立柔性机械臂的动态模型,进而利用奇异摄动理论得到柔性机械臂的双时间尺度模型.然后,基于慢时间尺度模型利用滑模控制理论设计轨迹跟踪控制器;借助于快时间尺度模型利用自适应动态规划设计参数不精确已知情况下的最优振动抑制控制器;将二者相结合,构造双时间尺度组合控制器,利用奇异摄动理论证明闭环系统稳定.最后,在MATLAB/Simulink环境下进行实验,与现有方法相比,本文设计的控制器对柔性振动具有更好的振动抑制效果,跟踪精度更高.