有限理性下参数最优化问题解的稳定性

主要研究有限理性下参数最优化问题解的稳定性. 即在两类扰动即目标函数及可行集二者, 目标函数、可行集及参数三者分别同时发生扰动的情形下, 对参数最优化问题引入一个抽象的理性函数, 分别建立了参数最优化问题的有限理性模型M, 运用``通有'的方法, 得到了上述两种扰动情形下相应的有限理性模型M的结构稳定性及对\varepsilon-平衡(解)的鲁棒性, 即有限理性下绝大多数的参数最优化问题的解都 是稳定的, 并以一个例子说明所得的稳定性结果均是正确的.     

不同耐热型春玉米品种对高温的光谱特征响应

运用两种光谱仪（SPAD-502叶绿素仪与Sunscan植物冠层分析仪）分析了华北平原不同耐热型春玉米品种的光合性能对灌浆期高温的光谱学特征响应。田间试验于2011年—2012年在河北省吴桥县进行。品种选用天玉198、兴玉998与天润606,设置2个播种期（4月15日与4月25日）,于灌浆期测定3个光谱特征值,即叶绿素相对含量（SPAD）、叶面积指数（leaf area index, LAI）与光合有效辐射（photosynthetically active radiation, PAR）。结果表明,播种期4月15日与4月25日相比,春玉米灌浆期≥33 ℃日最高气温的天数与日均温分别增加了3.5 d和0.8 ℃,而日照时数、降雨量、气温日较差及生育期长短均相似; 天玉198与兴玉998、天润606相比,耐热指数（stress tolerance indices, STI）分别高2.9%,11.0%; 根据STI由大到小的顺序,将天玉198、兴玉998与天润606分别定为耐热型、较耐热型与不耐热型品种; 播种期4月15日,天玉198比兴玉998、天润606的产量分别高4.1%,13.7%,SPAD分别高12.5%,19.6%,LAI分别高5.3%,5.6%,PAR分别高4.0%,14.0%; 播种期4月25日,产量分别高1.3%,2.8%; SPAD分别高3.5%,6.0%,LAI分别高1.7%,4.1%,PAR分别高-4.4%,0.9%; 三个品种在高温胁迫环境下产量差异显著,耐热型品种具有显著的产量、SPAD与LAI优势（p＜0.05）。播种期4月15日相对于4月25日,天玉198、兴玉998、天润606的产量分别降低了3.2%,5.9%,12.6%; SPAD分别降低了8.6%,12.4%,15.7%; LAI分别降低了11.7%,17.6%,19.8%; PAR分别降低了3.4%,11.3%,14.5%; STI与SPAD的降幅（r=-0.883,p＜0.05）、LAI的降幅（r=-0.853,p＜0.05）均呈显著负相关,与PAR的降幅（r=-0.923,p＜0.01）呈极显著负相关; SPAD的降幅与PAR的降幅（r=0.872,p＜0.05）呈显著正相关; LAI的降幅与PAR的降幅（r=0.943,p＜0.05）呈极显著正相关。综上所述,耐热型春玉米品种在灌浆期受高温胁迫时,能够在个体层面保持相对较高的叶绿素含量,在群体层面保持相对较高的叶面积,进而保持了较高的光能截获与利用,削弱了高温对光合的抑制程度,缩小了产量降幅,实现了高产与稳产; 品种的耐热性可以通过其光谱特征（SPAD,LAI和PAR）对高温的响应作为鉴定与评价的主要指标之一,为利用光谱特征研究玉米耐热性提供了依据。     

基于单摄像机和神经网络的三维测量研究

为了实现更为简单的三维测量同时解决传统立体视觉方法中基线的限制问题,提出一种单摄像机微小角度旋转结合神经网络进行三维测量的方法.方法通过单摄像机小角度旋转采集二维图像数据;利用电动平台移动标定板构建三维空间坐标系;基于摄像机的线性成像模型思想,将代表图像坐标和三维坐标映射关系的投影矩阵替换为BP神经网络,得到二维坐标到...     

新型LD泵浦振荡器与多程放大系统联机实验

 新型LD泵浦振荡器采用环形结构，具有单纵模几率高、时间波形和幅度高度稳定等特点，这些特点使其与多程放大器的联机非常方便，没有系统多脉冲注入破坏风险和能量不稳破坏风险。联机实验取得了显著成果，输出能量达1.252kJ，是当前国内固体激光器单束输出最高能量，此时输出脉冲脉宽为1.26ns，光束口径为20cm×20cm，平均功率密度达2.5GW/cm²。     

Methanol Conversion into Dimethyl Ether on the Anatase TiO2(001) Surface

Exploring reactions of methanol on TiO₂ surfaces is of great importance in both C1 chemistry and photocatalysis. Reported herein is a combined experimental and theoretical calculation study of methanol adsorption and reaction on a mineral anatase TiO₂(001)‐(1×4) surface. The methanol‐to‐dimethyl ether (DME) reaction was unambiguously identified to occur by the dehydration coupling of methoxy species at the fourfold‐coordinated Ti⁴⁺ sites (Ti_4c), and for the first time confirms the predicted higher reactivity of this facet compared to other reported TiO₂ facets. Surface chemistry of methanol on the anatase TiO₂(001)‐(1×4) surface is seldom affected by co‐chemisorbed water. These results not only greatly deepen the fundamental understanding of elementary surface reactions of methanol on TiO₂ surfaces but also show that TiO₂ with a high density of Ti_4c sites is a potentially active and selective catalyst for the important methanol‐to‐DME reaction.     

Recent advances in platelet engineering for anti-cancer therapies

Platelets contribute a major role in hemostasis by clumping and coagulation at the site of blood vessel injuries.In light of recent findings of a close relation...     

Magnetically confined states and transport property on the surface of a topological insulator

We study the electronic structure and transport for a quasi-one-dimensional channel constructed via two ferromagnetic (FM) stripes on the surface of a three-dimensional (3D) topological insulator (TI) in parallel (P) or antiparallel (AP) magnetization configuration along the vertical z$z$-direction. We demonstrate that the confined states which are localized inside the channel always exist due to the magnetic potential confinement. Interestingly, the channel is metallic because of the existence of a topologically protected gapless chiral edge mode in the case of AP configuration. The asymmetric spatial-distribution of both electron probability density and in-plane spin polarization for the confined states implies that in the case of P configuration there exists a chiral state near the channel edge owing to the Hamiltonian inversion symmetry broken in real space, while the distributions in AP case are always symmetry since the inversion symmetry is still kept. Furthermore, the transmission probability and the spatial-dependent distributions of charge and spin along a narrow–wide–narrow channel on the surface with P configuration confinement are also calculated, from which a fully in-plane spin-polarized electron output is achieved. Along with the mathematical analysis we provide an intuitive, topological understanding of these effects.     

SrTiO3的合成及其光催化还原CO2的性能

本文采用水热合成法制备钙钛矿型半导体光催化剂钛酸锶,紫外光激发下,在甲醇溶液中还原CO2制得甲酸甲酯,并通过负载Ag降低了电子与空穴的复合几率,有效地提高了光催化活性。同时,发现了Ag的负载量、负载方法以及表面活性剂对光催化活性的影响规律。借助XRD分析了催化剂的晶型并计算出颗粒的粒径,SEM、TEM、HRTEM观测了催化剂颗粒的形貌,UV-vis吸收光谱检测了其光激发特性。最终,获得了一步水热法制备Ag含量为5wt%的Ag/SrTiO3具有较高催化活性的优化实验结果。     

二氧化硅/聚苯乙烯复合微球的制备及作为固相萃取填料的研究

以分散聚合法制备了二氧化硅/聚苯乙烯单分散复合微球,以红外光谱、透射电镜(TEM)、扫描电镜(SEM)等手段对其进行了表征。以合成的二氧化硅/聚苯乙烯作为固相萃取填料制作固相萃取小柱。通过固相萃取与液相色谱联用,测定了水中邻硝基酚、间硝基酚、对硝基酚和辛基酚、壬基酚,考察了固相萃取条件对固相萃取柱性能的影响,选择了最佳的色谱分离条件。结果表明,自制固相萃取小柱对水中硝基酚、烷基酚的萃取率高,与HPLC联用测定结果重现性好,邻硝基酚、间硝基酚、对硝基酚、辛基酚、壬基酚的最低检出限分别为0.90、0.72、0.62、0.38和0.41μg/L。     

A detailed derivation of eigenvalue equation in two dimensional and three dimensional photonic crystals

A detailed derivation of eigenvalue equation in two dimensional and three dimensional photonic crystals is given by the plane-wave expansion method. Some mathematical formulas such as the rotation of vector, the gradient of scalar, the divergence of the vector, the vector triple product and the conversion between scalar and vector are employed. The eigenvalue equation in photonic crystals has become the important base for obtaining the band structure and the distribution of eigenmode.