Large deviations of sojourn times in processor sharing queues

This paper presents a large deviation analysis of the steady-state sojourn time distribution in the GI/G/1 PS queue. Logarithmic estimates are obtained under the assumption of the service time distribution having a light tail, thus supplementing recent results for the heavy-tailed setting. Our proof gives insight into the way a large sojourn time occurs, enabling the construction of an (asymptotically efficient) importance sampling algorithm. Finally our results for PS are compared to a number of other service disciplines, such as FCFS, LCFS, and SRPT. 2000 mathematics subject classification: 60K25.     

浅谈铜鼓太阳纹饰的源流

太阳和铜鼓都是古代先民自然崇拜的实体。早在远古时期，人类就形成了对太阳的崇拜，在发展变化的历史长河中，逐步将崇拜太阳的一些礼仪寄托在铜鼓之上，产生和发展了精美的铜鼓纹饰。     

Consistency of rank tests against some general alternatives

The proof of consistency of rank tests against some general alternatives is given. The alternatives considered include arbitrary, not necessarily monotone, trend in location or change points (change surfaces) under the infill asymptotics. One-dimensional and multi-dimensional cases are studied. The numerical experiment illustrating the usage of the above results for image analysis (edge detection) is presented.     

A new model for automatic normalization of multitemporal satellite images using Artificial Neural Network and mathematical methods

Relative Radiometric Normalization is often required in remote sensing image analyses particularly in the land cover change detection process. Normalization process minimizes the radiometric differences between two images caused by inequalities in the acquisition conditions rather than changes in surface reflectance. A wide range of RRN methods have been developed to adjust linear models. This paper proposes an automated Relative Radiometric Normalization (RRN) method to adjust a non-linear model based on an Artificial Neural Network (ANN) and unchanged pixels. The proposed method includes the following stages: (1) automatic detection of unchanged pixels based on a new idea that uses CVA (Change Vector Análysis) method, PCA (Principal Component Analysis) transformation and K-means clustering technique, (2) evaluation of different architectures of perceptron neural networks to find the best architecture for this specific task and (3) use of the aforementioned network for normalizing the subject image. The method has been implemented on two images taken by the TM sensor. Experimental results confirm the effectiveness of the presented technique in the automatic detection of unchanged pixels and minimizing imaging condition effects (i.e., atmosphere and other effective parameters).     

Spectral changes of partially coherent flat topped beam in turbulent atmosphere

Spectral characteristics of partially coherent flat-topped (PCFT) beams propagated in a turbulent atmosphere are investigated and an analytical formula for the spectrum S(ω) is derived. It is shown that, if the scaling law is valid, the normalized spectrum S(ω) of PCFT beams propagating through turbulent atmosphere is the same as the normalized source spectrum S⁽⁰⁾(ω), this similarity is valid for any arbitrary order of the circular flat-topped “N”. It is proved that if the scaling law is not valid, S(ω) of PCFT is different from S⁽⁰⁾(ω). Also spectral behavior of PCFT beams in free space and turbulence media is investigated in detail.     

Change of grading,injective dimension and dualizing complexes

Let G,H be groups, φ:G→H a group morphism, and A a G-graded algebra. The morphism φ induces an H-grading on A, and on any G-graded A-module, which thus becomes an H-graded A-module. Given an injective G-graded A-module, we give bounds for its injective dimension when seen as H-graded A-module. Following ideas by Van den Bergh, we give an application of our results to the stability of dualizing complexes through change of grading.     

Weibull分布尺度参数变点的假设检验

对Ｗｅｉｂｕｌ分布尺度参数只有一个变点的假设检验问题,运用Ｂａｙｅｓ方法和最小二乘法,分别给出了Ｗ＊检验和Ｕ检验,对Ｗ＊检验,给出了其密度函数的Ｅｄｇｅｗｏｒｔｈ展式,关于Ｕ检验,运用文［３］给出其渐近分布．据文［８,９］,也分别给出了两个非参数检验．     

河北省农业应对气候变化的对策研究

基于近50年来河北省气候变化趋势及其对河北省农业的影响分析,提出河北省农业的应对措施:调整农业结构和种植制度;发展生物技术等新技术,培育抗逆性强优质农作物品种,加强农业基础建设和农田基本建设,科学灌溉,协调用水,增强抗御气候变化而造成的缺水局面的能力;实施虚拟水资源战略,合理农业布局;建立健全极端天气应急方案,强化监测网建设;加强防灾、减灾、灾害恢复技术的研发和推广,不断提高农业对气侯变化的适应能力,实现农业的可持续发展。另一方面,要节能减排,植树造林生态固碳,多部门联动,推进低碳城乡化,为全球减缓气候变化做出贡献。     

Spatiotemporal Utilization of Latent Heat in Erythritol-based Phase Change Materials as Solar Thermal Fuels

Solar thermal fuels (STFs) have been particularly concerned as sustainable future energy due to their impressive ability to store solar energy in chemical bonds and controllably release thermal energy. However, currently studied STFs mainly focus on molecule-based materials with high photochemical activity, toxicity, and compromised features, which greatly restricts their applications in practical scenarios of solar energy utilization. Herein, we present a novel erythritol-based composite phase change material (PCM) as a new type of STFs with an outstanding capability to store solar energy as latent heat in its stable supercooling state and release thermal energy as needed. This composite PCM with stored thermal energy can be maintained stably at room temperature and subsequently release latent heat as high as 224.9 J/g during the crystallization process triggered by thermal stimuli. Remarkably, solar energy can be converted into latent heat stored in the composite PCM over months. Through mechanical stimulations, the released latent heat can increase the temperature of the composite up to 91 °C. This work presents a new concept of using spatiotemporal storage and release of latent heat in PCMs for solar energy utilization, making it a potential candidate as STFs for developing future clean energy techniques.     

溶剂对光致变色材料-乙基红的光学特性影响

研究了溶剂性质对光致变色材料乙基红光学性质的影响.用吸收谱测定了乙基红染料在不同溶剂中的溶剂化位移.对相同浓度多种乙基红溶液进行了Z-scan测量,测量了不同乙基红溶液的光限幅效应,并讨论了其与溶剂之间的关系.随极性增加,吸收谱蓝移,可以通过选择不同溶剂,改变非线性材料的应用窗口.实验结果表明,在连续光照射下,乙基红溶液的非线性折射主要由热效应引起,非线性折射系数n2受溶剂的热学性质影响较大.此外,Z-scan结果中的非线性吸收为饱和吸收.至于光限幅效应,主要受热效应影响,但亦可由吸收谱预测出在某波长处的动态范围.得出的结论有助于偶氮染料作为非线性材料的应用.