Geometric transformations on the hexagonal grid

The hexagonal grid has long been known to be superior to the more traditional rectangular grid system in many aspects in image processing and machine vision related fields. However, systematic developments of the mathematical backgrounds for the hexagonal grid are conspicuously lacking. The purpose of this paper is to study geometric transformations on the hexagonal grid. Formulations of the transformation matrices are carried out in a symmetrical hexagonal coordinate frame. A trio of new trigonometric functions are defined in this paper to facilitate the rotation transformations. A fast algorithm for rounding an arbitrary point to the nearest hexagonal grid point is also presented.     

Indexing the aperture 3 hexagonal discrete global grid

Over the past decade there has been interest in the computer representation of global data based on multi-resolution subdivisions of regular polyhedra. A simple and efficient indexing of the cells of such a subdivision, called A3-coordinates, is introduced. These can be used to encode the 4 · 3ⁿ + 2 cells at the nth level of resolution of the octahedral aperture 3 hexagonal discrete global grid using n + 3 digits, each digit from the set {−1, 0, 1}.     

Efficient backward selection ofk-space samples in MRI on a hexagonal grid

Certain types of magnetic resonance imaging (MRI) such as magnetic resonance spectroscopic imaging and three-dimensional (3D) MRI require a great deal of time to acquire the image data. The acquisition time can be reduced if the image has a limited region of support, such as when imaging the brain or a cross section of the chest. Hexagonal sampling of the spatial frequency-domain (k-space) yields a 13.4% sampling density reduction compared to rectangular sampling of thek-space for images with a circular region of support (ROS) without incurring spatial aliasing in the reconstructed image. However, certain nonuniform sampling patterns are more efficient than hexagonal sampling for the same ROS. Sequential backward selection (SBS) has been used in previous work to optimize a nonuniform set ofk-space samples selected from a rectangular grid. To reduce the selection time, we present SBS of samples from a hexagonal grid. A Smith normal decomposition is used to transform the nonrectangular 2D discrete Fourier transform to a standard rectangular 2D fast Fourier transform so that the spatial-domain samples are represented directly on a rectangular grid without interpolation. The hexagonal grid allows the SBS algorithm to begin with a smaller set of candidate samples so that fewer samples have to be eliminated. Simulation results show that a significantly reduced selection time can be achieved with the proposed method in comparison with SBS on a rectangular grid.This work was supported by a Biomedical Engineering Research Grant from the Whitaker Foundation.     

A generalized methodology for the gridding of microarray images with rectangular or hexagonal grid

Microarrays provide a simple way to measure the level of hybridization of known probes of interest with one or more samples under different conditions. The rapid development of microarray technology requires the implementation of smart and flexible algorithms to deal either with the great amount of data or with the variations of the used hardware. In this paper, a generalized methodology for spot addressing and gridding of microarray images is presented. The methodology can cope with both rectangular and hexagonal grids, which are used for the probes placement onto the substrate. Initially, the methodology identifies the structure of the image, and an efficient spot-by-spot approach has been developed for the detection of all spots in the image. The evaluation of the methodology was performed using both rectangular and hexagonal structured images, merged in a single dataset. The methodology results in high accuracy in the spots detection, ranging from 92.8 to 99.8 % depending on the dataset used.     

Getting a grip on the grid

When accidents occur in the systems that comprise an interconnected electric power grid, these accidents must be regarded as the symptom of inadequate grid design and management. As such, there is an urgent need for cross-regional reforms so that the best available technology is promptly put to use, without lengthy delays arising from the legislative or regulatory process. The reform process needs to recognize that all interconnected systems will experience major blackouts if operated outside intended design limits. Ultimately, end users must accept the price for reliability or the consequence of unavailability.     

关于网格中间件的研究

网格中间件是网格关键技术之一。研究的目的是为用户提供具有同一编程接口的虚拟机器,支持复杂应用问题的求解和广域网上各类资源的共享。美国、英国都很重视这方面的研究,NMI中间件计划、Internet2中间件计划都取得了很大进展。设计网格中间件要具备资源动态监测、屏蔽节点异构、优化资源选择和协同计算等功能。网格中间件包括资源监测组件、计算服务组件、网格安全组件、容错服务组件、信息服务组件和应用调度组件。成功的网格中间件典型范例说明,它可以更好地支持系统为用户提供高品质的服务以满足需求。     

Studies on grid emission

This paper is concerned only with the study of primary grid emission of various types of grid materials resulting from the evaporation products of L, impregnated, oxide-coated, and thoriated tungsten cathodes. The factors contributing to grid emission are analyzed. A detailed discussion of the performance of titanium, which exhibits excellent grid emission inhibiting properties, is included. In our investigation a planar triode construction was used, the grids of which consisted of a two-terminal loop of 0.010 inch diameter wire. In the assembly and processing utmost precautions were taken to insure minimum contamination of the various elements. The methods of assembly and processing are fully described in the paper. These tubes were tested using pulsed and dc techniques, and a discussion of the testing methods is included. The work function of a tungsten grid exposed to the evaporation products of the L, impregnated, and oxide-coated cathodes varies from 1.2 to 2.0 ev, the final value depending upon the past history of the cathodes, namely, the nature of the surface of the grid and the temperature and length of exposure to the cathodes.     

网格关键技术论析

信息技术的下一个浪潮高峰是万维网(World Wide Web)升级为网格(Grid)。了解、认识。进而应用网格技术意义重大。网格的关键技术主要有网格硬件、网格操作系统、网格应用层面、网格计算以及其他一些关键技术。     

Visualizing the electric grid

In the new world of competition, power traders, grid managers, public service boards, and the public itself all need to take in what's happening at a glance. Visualization software enables viewers to interpret the data more rapidly and more accurately than ever before. This kind of software will become still more useful, even indispensable, as electricity grids are integrated over ever-larger areas, as transmission and generation become competitive markets, and as transactions grow in number and complexity. Concepts like power flow, loop flow, and reactive power, which once mattered only to the engineers directly involved in grid operations, now must be made intuitive. This is because they must be communicated to public service commissions and the consumer-voters to whom such boards are answerable. In short, whether the client/user is a power marketer, a grid operator or manager, a public authority, or a member of the public, power system visualization tools can aid their comprehension by lifting the truly significant above background noise. Such tools can expedite decision-making for congestion management, power trading, market organization, and investment planning for the long term     

Empire off the grid

Dean Kamen, arguably the world's most famous living inventor, is in his favorite place. It's the basement of the main house on his private island, a pristine concrete bunker outfitted with a command station that can monitor and control all aspects of the production and consumption of electric power on the island. The island, off the coast of Connecticut, is called North Dumpling Island, but Kamen, who invented the Segway and is something of an eccentric, calls it the Dumplonian Empire. He, of course, is Lord Dumpling.     

网格信息服务初探

信息服务是网格系统提供给各类用户以满足需求的主要功能。由于信息资源的需求者与提供者分布在不同地域或不同节点上，二者是非透明状态下的，不均衡的“多对多”关系，因此，需要网格信息服务。数据网格和信息网格是网格信息服务的基础；SOA的优势在于其高度的可复用性、灵活性、可靠性和更好的可扩展性；Web服务描述了一种基于标准技术的新型分布式计算范例，并提供应用程序的接口WSDL。在Web协议的支持下，就可以为信息获取、信息提供、信息管理等提供基本操作，实现网格信息服务的功能。     

基于智能电网的EAM测距改进研究

随着国内智能电网的快速发展,无线传感器网络中的节点位置的难题成了急需改进的一个难点。文中采用自适应的方法完成了EAM测距设计,然后分析了EAM测距实现障碍物误差降低的特点,在对EAM测距MATLAB平台上的仿真表明相对于普通的测量方法,EAM的测距方法可以提高测距精度在25%左右,这一研究对于智能电网的发展具有一定的理论和实际意义。     

网格计算中的安全问题探讨

介绍了网格计算环境的特点、安全需求及其安全问题研究现状，对网格计算中的安全标准、安全认证、公有与私有资源的安全利用、应用安全、恶意攻击的检测与防范等安全问题进行了分析和讨论，提出了在研究和解决网格计算的安全问题时，一方面可以借鉴传统网络的安全策略和技术并加以改进，另一方面要充分考虑网格计算环境的特殊性，研究和构建“特殊．的安全策略和技术”。     

光伏并网发电问题研究

介绍了光伏并网发电的类型,分析了光伏并网发电对电网的影响,针对光伏并网发电的收益问题,提出了电网负荷预测模型。根据所提出的预测模型可以对光伏并网发电出力提供指导,以提高电网发电的效益。最后,以辽宁地区数据为例,绘制出了电网负荷与温度之间变化关系的拟合曲线。     

Distributed reduction algorithm on grid service

Pretreatment of mass and high dimensional data for users plays an important role for data mining in grid environment. To solve optimal reduction effectively, a distributed reduction algorithm on grid service is present. It combines grid services with a novel reduction algorithm on gene expression programming (GEP) (RA-GEP). Simulation experiments show that for mass or high dimensional data sets, the proposed algorithm has advantages in terms of speed and quality in contrast with traditional attribution reduction algorithms on intelligence computing.     

智能电网发展技术的研究

随着经济以及科学技术的发展,我国的电网也由传统电网向智能化电网的方向转变,客观上对电网工作人员的专业技术提出了更高的要求,笔者系统地分析了智能电网的主要特点,并就其中关键的技术要点与功能做出了简要的探究,以供同行参考,共同促进我国智能电网的发展进步。     

基于区块链的智能电网监控

随着智能电网系统的广泛应用,电力公司可以通过网络获取实时用电数据以满足负荷预测以及电力营销等业务需求,电力用户也可及时得知当月电费,甚至了解何时用电量较大以及哪个电器耗电量最大等具体细节,但这也导致了数据泄露的风险。为此文中利用主权区块链技术和智能合约的实施,为电力公司和电力用户之间提供一个可信任系统,使得电力供需双方都能安全、透明地获取用电数据。     

Parallel numerical applications on grid environments

Grid computing for electromagnetics is one of the few available books that present real applications running on grids. It's a practical book for researchers who want to set up a computational grid and understand the perspectives that grid computing platforms offer. It would also be suitable as a classroom text for undergraduate physics or electrical engineering students with some knowledge of computer networks, C programming, and numerical analysis.