Upper Bounds on the Covering Number of Galois-Planes with Small Order

Our paper deals with the covering number of finite projective planes which is related to an unsolved question of P. Erdös. An integer linear programming (ILP) formulation of the covering number of finite projective planes is introduced for projective planes of given orders. The mathematical programming based approach for this problem is new in the area of finite projective planes. Since the ILP problem is NP-hard and may involve up to 360.000 boolean variables for the considered problems, we propose a heuristic based on Simulated Annealing. The computational study gives a new insight into the structure of projective planes and their (minimal) blocking sets. This computational study indicates that the current theoretical results may be improved.     

Effective Heuristics for the GPS Survey Network of Malta: Simulated Annealing and Tabu Search Techniques

A GPS network can be defined as a set of stations, co-ordinated by a series of sessions formed by placing receivers on the stations. This paper shows how to search for the best order in which to observe these sessions giving the cheapest schedule. The complexity of observing GPS networks increases with their size and become highly difficult to solve effectively. To obtain good methods to solve this problem a new area of research is implemented. This area is based on developed heuristic techniques that provide an optimal or near optimal solution for large networks. Comparing their outcome in terms of solution quality and computational effort proves the performance of the developed techniques.     

Enhanced photodegradation of methylene blue with alkaline and transition‐metal ferrite nanophotocatalysts under direct sun light irradiation

It is highly desired to synthesize low‐cost photocatalysts for the degradation of colored dyes to safeguard our environment for the future generations. Here, we report an extremely efficient and low‐cost synthesis of alkaline earth and transition‐metal ferrite photocatalysts (MgFe₂O₄, CaFe₂O₄, BaFe₁₂O₁₉, CuFe₂O₄, and ZnFe₂O₄) from their chloride salts and their applications for the degradation of methylene blue (MB) dye under UV–visible and direct sunlight irradiation. The as‐prepared photocatalysts displayed enhanced photoactivities under both conditions of irradiation. After calcination at 600°C, the photocatalytic degradation increased significantly, and 96 and 85% MB was removed with ZnFe₂O₄ under UV–visible and direct sunlight irradiation, respectively. Moreover, large amounts of hydroxyl free radicals were produced under both irradiation conditions, which participated in the degradation of MB. The enhanced photodegradation activities of these photocatalysts are attributed to their extended visible light absorption and low bandgaps. This work will provide a feasible route to the synthesis of efficient and low‐cost photocatalysts to utilize sunlight for environmental remediation.     

玉米秸秆纤维素和半纤维素NIRS特征波长优选

预处理是提高玉米秸秆生物转化利用效率的有效途径。玉米秸秆经生物炼制转化为生物燃料时,转化率与其原料内的纤维素和半纤维素含量直接相关。为了实现对预处理后玉米秸秆的生物炼制过程的有效调控,提出使用近红外光谱(NIRS)对玉米秸秆的纤维素和半纤维素含量进行快速检测,解决传统化学方法测试速度慢、成本高的问题。为了提高NIRS检测的效率和精度,将遗传算法与模拟退火算法相结合构建遗传模拟退火算法(GSA)用于预处理后玉米秸秆纤维素和半纤维素含量NIRS特征波长优选。GSA算法以NIRS波长点数为码长进行二进制编码,以偏最小二乘法(PLS)回归模型的交叉验证均方根误差为目标函数,结合温度参数设计适应度函数,基于Metropolis判别准则实现扰动解的选择复制,能够在避免早熟的同时有效提高进化后期的搜索效率。采用碱预处理、生物预处理及其相结合的方法对采集的玉米秸秆进行预处理后制备样品120个,并测定其纤维素和半纤维素含量及NIRS。使用7点Savitzky-Golay平滑结合多元散射校正和标准正则变换对光谱进行预处理后,利用Kennard-Stone法按3∶1比例划分校正集和验证集。然后,使用GSA算法对NIRS全谱进行特征波长优选(记为Full-GSA)、对协同区间偏最小二乘法(SiPLS)优选后谱区进行特征波长优选(记为SiPLS-GSA)、对反向区间偏最小二乘法(BiPLS)优选后谱区进行特征波长优选(记为BiPLS-GSA),并使用PLS回归模型和验证集对特征波长优选结果进行评测。Full-GSA以全谱1 557个波长点为基因,执行16次算法,优选出118个纤维素特征波长点和164个半纤维素特征波长点。SiPLS-GSA经SiPLS优选的纤维素和半纤维素谱区波长点数分别为388个和160个,再经GSA进一步优选后得到157个纤维素特征波长点和148个半纤维素特征波长点。BiPLS-GSA经BiPLS优选的纤维素和半纤维素谱区波长点数分别为358个和180个,再经GSA进一步优选后得到130个纤维素特征波长点和153个半纤维素特征波长点。结果表明,通过波长优选,不仅参与建模的波长点数量显著减少,而且回归模型的性能显著优于全谱建模。其中,采用Full-GSA优选的纤维素特征光谱回归性能最佳,采用SiPLS-GSA优选的半纤维素特征光谱回归性能最佳。回归模型验证集的平均相对误差(MRE)分别为1.752 4%和2.020 8%,较全谱建模分别降低了13.636 6%和25.368 4%。基于结合温度参数设计适应度函数的策略构建的GSA具有良好的全局搜索性能,适用于玉米秸秆纤维素和半纤维素含量NIRS特征波长优选。GSA以全谱每个波长点为染色体基因的编码方案适用于NIRS全谱的特征波长优选。GSA同样适用于SiPLS和BiPLS优选后谱区的特征波长优选,能够有效实现优选后谱区的波长点优选。     

Remote sensing of atmospheric duct parameters using simulated annealing

Simulated annealing is one of the robust optimization schemes. Simulated annealing mimics the annealing process of the slow cooling of a heated metal to reach a stable minimum energy state. In this paper, we adopt simulated annealing to study the problem of the remote sensing of atmospheric duct parameters for two different geometries of propagation measurement. One is from a single emitter to an array of radio receivers (vertical measurements), and the other is from the radar clutter returns (horizontal measurements). Basic principles of simulated annealing and its applications to refractivity estimation are introduced. The performance of this method is validated using numerical experiments and field measurements collected at the East China Sea. The retrieved results demonstrate the feasibility of simulated annealing for near real-time atmospheric refractivity estimation. For comparison, the retrievals of the genetic algorithm are also presented. The comparisons indicate that the convergence speed of simulated annealing is faster than that of the genetic algorithm, while the anti-noise ability of the genetic algorithm is better than that of simulated annealing.     

非对称半结晶两嵌段共聚物的微相分离与结晶行为的模拟退火研究

利用模拟退火方法研究非对称半结晶两嵌段共聚物熔体分别在弱分离和强分离条件下的结晶过程.考察微相分离作用和结晶作用的相对强度对柱状组成的两嵌段共聚物平衡形态的影响.研究结果表明,当嵌段间的相互排斥作用较弱时,结晶便破坏了柱状畴;当此相互作用足够强时,结晶过程可以有效地被限制在熔体微相分离所形成的柱状畴内.另外,介于上述两种情形之间还存在一个模板区域,此时熔体形成的柱状畴大部分被保留下来,但在局部会变形或连通.这些结果和文献报道的实验结果一致.当嵌段间的相互排斥作用非常强时,结晶被抑制,微相分离主导最终形态,观察到了非晶态结构.     

Determination of Polarity Terms of Some Nitrogen-Containing Surfactants and Simulated Hydrophobic Tail Models by Gas Chromatography

Some polarity terms of two groups of nitrogen-containing surfactants （ six alkanolamides and nine polyoxyethylenated long chain amines） are measured through gas chromatography. The apparent methanol carbon number （CMeOH） and polarity index （IP） values are determined on the investigated surfactants as stationary phases in packed columns. Similarly, CMeOH and IP values are determined on simulated hydrophobic tail （SHT）models. The obtained results reveal that the introduction of SHT approach permits the distinction between the polarities of different surfactants and their head groups. The measured polarity terms are discussed as related to hydrophile-lipophile balance （HLB） number and the hydrophobic group carbon number （RCN）. Some equations relating the measured polarity values and these variable have been developed.     

海洋光学浮标的设计及应用试验

海洋光学浮标在水色遥感现场辐射定标和数据真实性检验、海洋科学观测、近海海洋环境监测等方面有重要应用价值。采用子母浮标技术设计了海洋光学浮标系统,该系统可同步测量海面和海水近表层及真光层的光谱辐照度和光谱辐亮度分布、水体光谱吸收/散射系数,以及风速风向等辅助参数。浮标利用GPS定位,采用低功耗的PC104嵌入式电脑作为控制核心实现数据的自动采集,采用CDMA/GPRS无线网络与海事卫星两种方式实现数据和指令的实时传输。近海试验表明,设计的子母浮标能较好地满足水下光辐射测量对浮标姿态和稳性的要求,系统的数据采集和远程传输技术可靠,光学仪器防污染技术能确保光学浮标长期有效地工作。     

使用模拟退火算法解课表问题

给出一种使用模拟退火算法 (SSA)求解课表问题的方案 ,详细地讨论了该方案涉及的各种问题 ,包括目标函数和初解的确定 ,邻域和新解的产生方法 ,初始“温度”的确定和“温度”更新的方式 ,内循环次数及算法终止条件的确定等 .文章的最后给出了该方案的一个实例和若干性能分析 .     

Convergence of the Simulated Annealing Algorithm for Continuous Global Optimization

A class of simulated annealing algorithms for continuous global optimization is considered in this paper. The global convergence property is analyzed with respect to the objective value sequence and the minimum objective value sequence induced by simulated annealing algorithms. The convergence analysis provides the appropriate conditions on both the generation probability density function and the temperature updating function. Different forms of temperature updating functions are obtained with respect to different kinds of generation probability density functions, leading to different types of simulated annealing algorithms which all guarantee the convergence to the global optimum.