一种基于最大相似子阵的彩色图像检索算法

颜色是图像的重要特征之一,被广泛用于图像检索。传统的颜色直方图检索算法丢弃了色彩的空间位置信息,影响了算法的检索精度。针对这一问题,提出了一种基于最大相似子阵的彩色图像检索算法,即采用奇数方阵分割图像以捕捉颜色的空间分布特征,从而得到颜色矩阵,通过求解两个颜色矩阵的最大相似子阵实现相似度计算。研究结果表明,所提算法能够准确描述图像的颜色特征,相似度计算非常有效,相比全局直方图有较好的检索精度。     

Evaporative heat loss and heat transfer for open- and closed-cycle systems of a floating tilted wick solar still

An analytical expression for the thermal efficiency of evaporative heat loss and heat transfer for a open- and closed-cycle systems of floating tilted wick solar stills in terms of system design and climatic parameters has been derived. The expression for open- and closed-cycle systems was validated by performing experiments for both systems. Optimization of the design of the still for evaporative cooling (open cycle) and the distillation unit (closed cycle) was obtained using the derived analytical expression for large-scale installation. Numerical calculations were also carried out for a typical summer day at the Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore, India, to predict the performance of the still.     

碳羟基磷灰石对废水中Cd2+的吸附

利用废弃蛋壳制备碳羟基磷灰石,并利用其吸附废水中的Cd2 .考察了Cd2 初始浓度、pH值、吸附时间、吸附剂用量以及温度等因素对吸附效果的影响,结果表明:当废水中Cd2 初始浓度为30 mg/L、pH=7、吸附时间35 m in、温度35℃时,碳羟基磷灰石对Cd2 去除率高达99.9%.吸附实验还表明该吸附符合Freundlich方程.     

Variation of the photoluminescence and vacuum ultraviolet excitation characteristics of BaZr(BO3)2:Eu3+ by the incorporation of Al3+, La3+, or Y3+ into the lattice

The photoluminescence (PL) and vacuum ultraviolet (VUV) excitation properties are studied for the BaZr(BO₃)₂:Eu³⁺ phosphor with incorporating the Al³⁺, La³⁺, or Y³⁺ ion into the lattice. The excitation spectrum shows an absorption band in the VUV region with the band-edge at 200 nm and a very weak charge transfer band of Eu³⁺ at about 226 nm. The luminescence spectrum shows a strong emission at 615 nm (⁵D₀ → ⁷F₂ transition) and weak emission at 594 nm (⁵D₀ → ⁷F₁ transition) in BaZr(BO₃)₂:Eu³⁺, with a good red color purity. The PL intensity is increased by incorporating Al³⁺ into the BaZr(BO₃)₂ lattice. The PL intensity has also increased by incorporating La³⁺ into the lattice, however, the red color purity has deteriorated because of the increased centrosymmetric nature of the site. With the incorporation of Y³⁺ into the BaZr(BO₃)₂ lattice, the PL characteristics of the Eu³⁺ activator resembles that in the YBO₃ lattices. The intensity of the red PL for the Eu³⁺ activator is the highest with good color purity for BaZr(BO₃)₂:Eu³⁺ incorporated with both Al³⁺ (10%) and La³⁺ (0.5%).     

A novel green emitting phosphor Ca2GeO4:Tb3+

A novel green emitting phosphor, Tb³⁺-doped Ca₂GeO₄ was prepared for the first time by a solid-state reaction. The phosphor showed prominent luminescence in green due to the magnetic dipole transition of ⁵D₄ → ⁷F₅. Structural characterization of the luminescent material was carried out with X-ray powder diffraction (XRD) analysis and field emission scanning electron microscopy (FE-SEM). Luminescence properties were analyzed by measuring the excitation and photoluminescence spectra. Photoluminescence measurements indicated that the phosphor exhibited bright green emission at about 541 and 550 nm under UV excitation. In addition, Al³⁺ or Li⁺ co-doping enhances the green emission from Ca₂GeO₄:Tb³⁺ by about 18 and 4 times, respectively, under UV excitation. The excellent luminescence properties make it a possible candidate for flat panel display application.     

Power grand composite curves shaping for adaptive energy management of hybrid microgrids

This work proposes a systematic approach for the adaptive identification and implementation of efficient power management strategies (PMS) in the course of operation of hybrid renewable energy microgrids. The approach is based on the temporal evolution of the system power grand composite curve (PGCC), which is adaptively shaped on-line and within short-term time intervals to form a sequence of decisions indicating the instant and duration of activation of different subsystems. It builds on from previous work where the potential for system performance enhancement could not be exploited through pre-specified PMS identified off-line. More specifically, it involves a stored energy targeting step that exploits the PGCC to identify the desired operational profile of an accumulator during a prediction horizon in order to satisfy the system operating goals. The identified energy targets are subsequently enforced through a sequence of control actions that enable the exact matching of the PGCC hence resulting in a new PMS. The method is elaborated graphically for multiple potential operating goals and is supported by a formal mathematical model that captures system structural and temporal characteristics. It is implemented on an actual hybrid microgrid considering multiple RES-based energy generation and storage options for expected and unexpected weather conditions.     

Building Model as a Service to support geosciences

Modeling is a fundamental methodology for simulating the past, understanding the present and predicting the future of the geospatial systems and phenomena. However, modeling in the geospatial science poses several challenges, including complex model setup, repetition in model setup, requirement for large, scalable computing resources, and management of a large amount of model output. To address these challenges, we propose Model as a Service (MaaS) by leveraging the latest advancement of cloud computing. MaaS enables various geoscience models to be published as services, and these services can be accessed through a simple web interface. MaaS automates the processes of configuring machines, setting up and running models, and managing model outputs. The computing resources are automatically provisioned by MaaS in a cloud environment. A proof-of-concept MaaS prototype is presented using a global climate change model (ModelE). Experimental results show that the MaaS prototype significantly simplifies model setup, accelerates model simulation and enhances model output by providing a web-based, on-demand, scalable modeling environment.     

Surface and crystalline analysis of aluminum oxide single crystal treated by quasistationary compression plasma flow

Material such as aluminum oxide (Al₂O₃) is important in electronics industry. On the other hand, plasma is one of the most efficient and sophisticated tools for materials processing. In this work a treatment of Al₂O₃ (0001) surface by quasistationary compression plasma flow (CPF) is analyzed in detail. Offline metrology was performed using dielectric measurements, X-ray diffraction (XRD), scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM). Oriented low-dimensional periodic structures are occurred for the plasma treated Al₂O₃ single crystal. In the paper is reported that these oriented ripple-shaped structures contain a higher percentage of oxygen than the surrounding crystal surface. This could be the framework for usage of CPF as a tool in manufacturing of surfaces containing the highly organized oxygen-rich structures.     

Correlation between the adsorption ability and reduction degree of graphene oxide and tuning of adsorption of phenolic compounds

Graphene oxide (GO) was prepared with a modified Hummers method and then reduced to different reduction degrees by using hydrazinehydrate. The obtained GO and reduced GO (RGO) were characterized. It was found that the reduction removed most of the oxygen-containing functional groups on the surface of GO. By using naphthalene as a probe, the interaction between RGO and organic molecules was evaluated with NMR. It was confirmed that the reduction of GO increased significantly the interaction between the π system of graphene and the π unit of organic molecules. The thermodynamic analysis indicated that the adsorption was a spontaneous, exothermic and entropy-decreasing process. It was observed that the adsorption capacities were generally increased with increasing the reduction degree of GO. The chemical structures of phenolics also affected their adsorption on RGO. The adsorption of the phenolics on RGO was enhanced by introducing electron-donating and withdrawing functional groups on the benzene ring. Depending on the chemical structures of phenolics, the surface reduction of GO to RGO-1 significantly increased the adsorption capacity for phenolics by a factor as large as 235%. A possible adsorption mechanism and correlation between the adsorption ability, reduction degree of GO and chemical structures of phenolics was discussed.     

Correcting the uneven burden sharing of emission reduction across provinces in China

Although China committed to reduce its energy and emission intensity, the allocation of such national targets in the provincial level is still a political negotiation process and lack of a systematic principle from the perspective of efficiency. This paper proposes an allocation principle based on the efficiency levels. The efficiency levels are estimated by employing a stochastic frontier analysis approach and the links between energy intensity and efficiency are constructed. The results show that energy efficiency change is not the major contributor to energy intensity reduction. Furthermore, this analysis indicates that (i) the efficiency-based allocation can distribute reduction burdens among regions smoothly compared to the intensity-based allocation; and (ii) the national target of emission intensity reduction can be achieved solely through efficiency measures.