Non-iterative load-flow method as a tool for voltage stability studies

Here the use of a non-iterative (NI) method for load-flow solutions is investigated. The method, previously proposed in the literature, presents some advantages in comparison with the iterative approaches usually employed. There, because the Taylor expansion is used, the power flow Jacobian matrix is not updated along the process. Here, some improvements in the implementation are executed, and few control actions are incorporated into the formulation. The method is then applied for voltage stability studies, aiming to reduce the computational time associated with     

对两个频率相近成分作频谱校正的非迭代形式研究

双频率模型(DFM)的频谱校正是否存在类似于单频率模型(CSM)的非迭代校正形式,以及相应的校正性能尚未见文献报道。作者分析了CSM存在简单校正公式的原因,给出了DFM加矩形窗的非迭代校正式,采用包含幅度相差10倍的DFM对校正式进行了仿真考核。研究结果表明:CSM存在简单校正式的原因在于窗谱函数可以分解为超越函数与有理分式的乘积,前者在相邻的离散谱线上绝对值相等;由这两个特性可建立DFM相对简单频谱校正关系,但是除了DFM加矩形窗的情形外,其它均涉及高于2次的多项式方程。仿真考核表明,给出的校正式对幅度强的成分的误差小于幅度弱者,并且当DFM频率间隔超过两个经典频率分别率时,最后采用CSM校正式。     

Non-iterative solution of finite-element equations in incompressible solids

Summary. Finite-element equations for incompressible and near-incompressible media give rise to a matrix with a diagonal block of zeroes or very small numbers. The matrices are not amenable to conventional techniques involving pivoting on diagonal entries. Uzawa methods have been applied to the associated linear systems. They are iterative and converge when the matrix is nonsingular. In the current study an alternate form of the matrix is used which is amenable to a solution without iteration. It likewise is applicable whenever the matrix is nonsingular. The solution process consists of a block LU factorization, followed by Cholesky decomposition of a positive definite diagonal block together with several forward and backward substitution operations. Two illustrative examples are developed.     

基于时域加权的单位脉冲响应模型的非叠代算法

提出了一种基于时域加权的新的非叠代优化算法,用于重构经过采样示波器测量的阶跃信号、脉冲信号等。该算法构造了一个期望误差函数,由于这个期望误差函数与真实误差很接近,因此构造了新的价值函数,并使用时域加权来优化不同的波形,在减小时域振铃时有效的控制噪声放大。与误差能量,归一化方法相比,该算法经过仿真实验表明了其可行性和有效性。     

Non-iterative data-processing algorithms for source location on the basis of measured differences in distance

Different groups of direct non-interative algorithms for analyzing measurement data from a multiposition sensing system designed to locate sources of radiation are systematically derived and classified. The features and range of application of the algorithms are discussed. A power analyis is performed and analytic relations are obtained for matrices describing the covariance of source-coordinate estimates obtained by the algorithms within the context of first-order perturbation theory. Translated from Izmeritel'naya Tekhnika, No. 7, pp. 32– 36, July, 1996.     

Non-iterative solution of a tridiagonal-type matrix coupled by diagonal submatrices

A non-iterative method is presented for solving a system of algebraic equations forming a banded matrix with each diagonal submatrix being tridiagonal and all other submatrices being diagonal. A recursion relation is assumed between successive elements of the solution vector. This relation is determined by equating a linearly combined form of it with the original set of equations also being linearly combined. The solution vector is determined by back-substitution of elements in the recursion relation. Since the method takes advantage of the banded structure of the matrix, it is more efficient than the conventional methods. A FORTRAN program that incorporates the present method is included.     

Large-scale App privacy governance

Recently, the problem of mobile applications (Apps) leaking users’ private information has aroused wide concern. As the number of Apps continuously increases, effective large-scale App governance is a major challenge. Currently, the government mainly filters out Apps with potential privacy problems manually. Such approach is inefficient with limited searching scope. In this regard, we propose a quantitative method to filter out problematic Apps on a large scale. We introduce Privacy Level (P-Level) to measure an App’s probability of leaking privacy. P-Level is calculated on the basis of Permission-based Privacy Value (P-Privacy) and Usage-based Privacy Value (U-Privacy). The former considers App permission setting, whereas the latter considers App usage. We first illustrate the privacy value model and computation results of both values based on real-world dataset. Subsequently, we introduce the P-Level computing model. We also define the P-Level computed on our dataset as the PL standard. We analyze the distribution of average usage and number of Apps under the levels given in the PL standard, which may provoke insights into the large-scale App governance. Through P-Privacy, U-Privacy, and P-Level, potentially problematic Apps can be filtered out efficiently, thereby making up for the shortcoming of being manual.     

一种路网环境下LBS隐私保护算法

近年来,基于位置服务(LBS)的应用越来越广泛.用户在享受这种位置服务带来的方便快捷之同时,也要承担可能暴露自身隐私信息(如位置等)的风险.目前,很多工作已经在诸如保护用户隐私信息方面取得了重大进展,但大多是集中于欧氏空间下的隐私保护技术,而路网环境下的隐私保护研究相对较少.针对路网环境下用户边权分布不均的问题,提出了基于哑元的边权均衡算法,即在保证匿名集中各路段邻近性的同时,以生成哑元的方式均衡各边边权分布.这样既能最大程度降低查询代价,又能使边权分布不会太分散.最后,通过实验验证了本算法的有效性,同时显示该算法还能有效防止边权分布不均引发的推断攻击.     

面向社交网络分析的差分隐私保护研究综述

阐述了数据的差分隐私保护概念,给出了差分隐私保护模型,从理论上描述了其噪声机制和组合性质,着重进述了差分隐私保护模型在社交网络发布数据隐私保护上的应用及发展,给出了差分隐私保护应用于度分布查询、子图计数、聚类系数计算、边权重计算等社交网络分析技术的实验结果。分析发现,研究差分隐私保护应重点考虑隐私预算和噪声机制,隐私预算决定了隐私保护强度,噪声机制决定了查询准确性;探讨差分隐私保护在社交网络领域的应用,是一个重要的研究方向。     

Contextual heat island assessment for pavement preservation

Pavement preservation (PP) is a planned set of construction and material interventions that can extend the pavement’s service life and may also impact sustainability through Heat Island (HI) mitigation. The HI mitigation potential can vary from location-to-location and with time. For agencies to widely adopt the PP, it is necessary to quantify the benefits based on the context of the project. A method to calculate the Global Warming Potential (GWP) for the HI effect was developed and illustrated for four cities in the US: Chicago, Austin, San Diego and Philadelphia, for hypothetical pavements with three preservation options: chip seals, a concrete inlay, and an asphalt concrete inlay. The use phase GWP with respect to HI was estimated for all cases given a 2-, 5-, 7- or 10-year service life. Overall, the HI in the use phase was found to dominate the total GWP relative to the materials and construction phases. The HI GWP savings increase over time, with the 10-year savings being greatest for San Diego using the concrete inlay (22.5?kg CO₂-eq/m²) and smallest for Chicago with a chip seal (8.0?kg CO₂-eq/m²). The savings were found to increase in areas that have a more pronounced HI and could offset GWP in the other phases. The proposed method allows agencies to estimate HI GWP for a specific preservation strategy, location and service life.     

Protecting our privacy in smart cities

正Cloud computing,the Internet of Things,mobile networks and artificial intelligence are just some of the tools cities use to increase efficiency and improve the quality of life of their citizens,yet they also expose us to risks and vulnerabilities related to personal privacy and security.Solutions and standards abound,but they are not always easy to navigate when the systems and interconnections are as complex as the stakeholders are many.     

HERA-B framework for online calibration and alignment

This paper describes the architecture and implementation of the HERA-B framework for online calibration and alignment. At HERA-B the performance of all trigger levels, including the online reconstruction, strongly depends on using the appropriate calibration and alignment constants, which might change during data taking. A system to monitor, recompute and distribute those constants to online processes has been integrated in the data acquisition and trigger systems.     

Silicon photomultipliers for radioactive waste online monitoring

A prototype demonstrator for the online monitoring of short-medium term radioactive waste repositories is currently under development at INFN-LNS. Such a system is planned to be distributed, fine-grained, robust, reliable, and based on low-cost components. With the main purpose of counting gamma radiation, we implemented a new kind of mini-detector based on silicon photomultipliers and scintillating fibers that behaves like a cheap scintillating Geiger-Muller counter and is suitable to be deployed in the shape of a grid around waste drums.     

Multivariate SPC for recipe preservation of batch processes

The performances of the Hotelling's T² control chart and the squared prediction error control chart based on the multi‐way principal component analysis are evaluated for monitoring within batch process variation for the purpose of recipe preservation. A nonlinear model for simulated batch process data is provided. The model allows for cross correlation of error terms at a given time period and serial correlation of error terms across time periods. The performance characterizations of the two monitoring schemes are provided for a variety of levels of cross correlation and serial correlation. The impact of the time period at which process shifts occur is also investigated for the monitoring schemes. The T² control chart is recommended for the cases considered. Copyright © 2009 John Wiley & Sons, Ltd.     

Evaluation of plastic packages for guava refrigerated preservation

Guavas cv. ‘Kumagai’ were packed in several plastic materials and stored at 10°C and 85–90% relative humidity (RH) for 7, 14, 21 and 28 days (+3 days at 25°C). The plastic materials studied were: multilayer co‐extruded polyolephine film with selective permeability (PSP), low‐density polyethylene film (LDPE), LDPE film with mineral incorporation (LDPEm) and heat‐shrinkable polyolephine film (SHR). Guavas not packed were taken as control samples. The physicochemical characteristics of the fruits, O₂ and CO₂ transmission rates of the packaging materials and gas composition at the package headspace were evaluated. The LDPE film, 69 µm in thickness, with the lowest permeability to both O₂ and CO₂, led to anaerobiosis and high CO₂ concentration inside the packages and promoted physiological disturbances and changes in fruit flavour. The SHR film, 15 µm in thickness, was the most permeable to CO₂ and had quite high O₂ transmission, which modified the inner atmosphere of the packages slightly. The fruits packed in this film showed a poorer quality than the controls, possibly due to the heat produced during the shrinking of the film. The LDPEm film, 24 µm in thickness, was almost as permeable to CO₂ but had reduced O₂ transmission, promoting an atmosphere of equilibrium of 3% O₂ and 4.5% CO₂. Fruits packed in this film kept their skin colour and pulp firmness, suitable for consumption up to 14 days. The PSP film, 35 µm in thickness, had the greatest O₂ transmission but just over half of the CO₂ transmission of LDPEm, promoting an atmosphere of equilibrium of 0.5% O₂ and 4.5% CO₂ inside the packages. Fruits packed in such packages kept their physicochemical characteristics up to 21 days. Copyright © 2001 John Wiley & Sons, Ltd.     

Employee privacy: legal and research developments and implications for personnel administration

The contemporary emphasis on privacy has created a myriad of complex personnel problems and associated approaches to handle them. These privacy-oriented problems generally involve social, ethical, legal, managerial, and even political considerations. Personnel administrators are constantly confronted with the privacy issue. This article attempts to synthesize privacy information relevant to personnel administration, and to provide personnel administrators with managerial guidance for handling employee privacy problems in the work environment. It places particular emphasis on differentiating between ethical and legal aspects of privacy in our society, and, accordingly, on clarifying existing confusion over the impact of so-called "privacy laws" on personnel administration.     

Validating online reference managers for scholarly impact measurement

This paper investigates whether CiteULike and Mendeley are useful for measuring scholarly influence, using a sample of 1,613 papers published in Nature and Science in 2007. Traditional citation counts from the Web of Science (WoS) were used as benchmarks to compare with the number of users who bookmarked the articles in one of the two free online reference manager sites. Statistically significant correlations were found between the user counts and the corresponding WoS citation counts, suggesting that this type of influence is related in some way to traditional citation-based scholarly impact but the number of users of these systems seems to be still too small for them to challenge traditional citation indexes.