Traceable P2P record exchange: a database-oriented approach

In recent years, peer-to-peer (P2P) technologies are used for flexible and scalable information exchange in the Internet, but there exist problems to be solved for reliable information exchange. It is important to trace how data circulates between peers and how data modifications are performed during the circulation before reaching the destination for enhancing the reliability of exchanged information. However, such lineage tracing is not easy in current P2P networks, since data replications and modifications are performed independently by autonomous peers—this creates a lack of reliability among the records exchanged. In this paper, we propose a framework for traceable record exchange in a P2P network. By managing historical information in distributed peers, we make the modification and exchange histories of records traceable. One of the features of our work is that the database technologies are utilized for realizing the framework. Histories are maintained in a relational database in each peer, and tracing queries are written in the datalog query language and executed in a P2P network by cooperating peers. This paper describes the concept of the framework and overviews the approach to query processing.     

Short‐Term Wind Power Prediction for Wind Turbine via Kalman Filter Based on JIT Modeling

This paper addresses wind power prediction, which is known to be a key technology in energy management systems. In this paper, a 24‐h‐ahead power prediction method using a filter theory is proposed for wind power generation. The prediction method is a simple algorithm. The procedure of prediction consists of two steps: the data processing and the calculation of the predicted values. In data processing, in order to obtain the correlative data from the database, we employ just‐in‐time modeling. In the calculation of the predicted values, we propose a regression model for wind speed and wind power, and the unknown parameters are estimated using a constrained Kalman filter. Moreover, in the procedure used to estimate the unknown parameters, reduction and convergence of the variables are also guaranteed. Finally, the advantages of the proposed method over the conventional method are shown through actual prediction evaluations.     

含黏粒砂土场地液化离心机振动台试验研究

提出了含黏粒砂土模型地基制备、饱和与均匀性监测技术,利用ZJU-400土工离心机振动台开展了相同相对密度含黏粒砂土（黏粒含量10%）和洁净砂的地震液化模型试验,再现了水平场地地震液化现象,揭示了含黏粒砂土场地液化灾变特点。弯曲元波速监测表明,模型制备均匀性良好,相同条件下含黏粒砂土剪切波速比洁净砂低。而根据超静孔压消散与固结沉降观测分析发现,含黏粒砂土渗透系数比洁净砂低一个数量级,从而影响其液化前后超静孔压响应和应力应变行为。渗透性差异导致模型内超静孔压产生模式和消散速率显著不同,振动时含黏粒砂土模型浅层超静孔压累积比洁净砂慢,而深层则相反;震后含黏粒砂土孔压消散时间是洁净砂的15倍。液化过程中含黏粒砂土剪应力应变响应比相同深度处的洁净砂更显著,液化后其滞回圈应变较大、割线模量较小且阻尼比较大。土体液化沉降主要发生在液化后超静孔压消散过程,含黏粒砂土模型超静孔压消散时间更长,沉降量更大。上述成果为进一步研究含黏粒砂土地震响应分析及其液化判别提供了科学依据。     

砂土液化后再固结体变规律表征与离心模型试验验证

针对一定相对密度的饱和砂土,首先开展单元体K₀固结试验和振动液化试验研究,发现饱和砂土液化后体变规律受再沉积和再固结两种机制制约：其中再沉积部分与所受振动历史密切相关,尤其是液化触发后的应变历史,土骨架累积剪应变比越大、再沉积体变越大;而再固结部分受先期固结历史和循环振动历史影响显著,再固结曲线会沿原有正常固结曲线趋势发展,其稳定段再压缩指数比相同条件下的正常固结曲线的压缩指数稍大。据此提出了考虑先期固结和振动历史的砂土液化后体变模型和简化算法,将再沉积和再固结两者统一表达成再固结体变,并建议了再固结压缩指数和假设起始应力的确定方法。进一步开展了水平场地地震液化离心机模型试验,监测模型固结和振动液化过程的沉降,从模型尺度进一步揭示砂土液化后体变规律,并初步验证了本文模型与简化算法的有效性。     

Time Evolution of Demixing in Oxides under an Oxygen Potential Gradient

Time evolution of concentration profiles leading to steady-state demixing in oxides under oxygen partial pressure gradient is treated based on a microscopic model by applying the path probability method of irreversible statistical mechanics. The redistribution of vacancies and cations toward the steady-state distribution has essentially been reduced to the diffusion of vacancies and the interdiffusion of cations along the specimen. Atomistic features of the problem, such as a vast difference in the relaxation times for the redistribution of vacancies and cations, are emphasized. Time required for the system to reach the steady state is then estimated in terms of fundamental material properties.     

Method for Diffusing Carrier Noise under Zero‐Speed Condition using a Zero‐Sequence Voltage

In this paper, a technique is proposed to reduce the carrier noise of pulse width modulation (PWM) inverters for a permanent magnet motor drive. The carrier noise is generated by the motor and the reactor driven by the inverter and affected by the switching frequency. When a motor rotates and drives a machine, the carrier noise is hidden by the machine noise. However, when the motor speed is approximately zero, the carrier noise becomes dominant and raucous. The typical method to reduce the noise employs a switching frequency higher than the audible frequency of human hearing. However, the increase in switching frequency results in the inverter suffering a higher switching loss and lower efficiency. In particular, when the permanent magnet motor operates at approximately zero‐speed and full‐load, for example, in the hill‐start conditions of electric vehicles and the start and stop conditions of elevators, the current flows in specific power devices and the switching loss further increases. The proposed technique uses a zero‐sequence voltage, which is generated randomly with the M‐sequence signal, and diffuses the frequency components of the ripple contained in the current. The technique is able to reduce the noise without increasing the switching frequency of the inverter when the motor speed is almost zero. Simulation and experimental results show that the proposed technique can diffuse the carrier noise and the cycle of the M‐sequence signal changes the diffusion effect of the carrier noise.     

In-situ observation of shape and atomic structure of Xe nanocrystals embedded in aluminium

An imaging technique to determine in situ the shape and atomic structure of nanosized Xe crystals embedded in Al is described using high-resolution transmission electron microscopy (HRTEM). The Xe nanocrystals, with sizes less than 5 nm were prepared by the implantation of 30 keV Xe⁺ into Al at room temperature. The fcc Xe nanocrystals are mesotactic with the Al lattice and have a lattice parameter ≈ 50% larger than that of Al. HRTEM images of the Xe were not clear in [110] zone axis illumination because of the small number of Xe atoms relative to Al atoms in any atom column. An off-axial imaging technique that consists of tilting the specimen several degrees from a zone axis and defocusing to suppress the Al lattice fringes is employed for the 110 projection of the Xe/Al system and the structure of the Xe nanocrystals is successfully imaged. The Xe images clearly represent projections of cuboctahedra with faces parallel to eight Al {111} planes truncated by six {100} planes. The results of multislice image simulations using a three-dimensional atomic model agreed well with the results obtained by the off-axial imaging technique. The usefulness of the technique is demonstrated with observations of crystal defects introduced into the Xe under intense 1000 keV electron irradiation.     

管线用高性能UOE钢管

对于天然气输送用管线钢管,在要求高强度的同时还要求其具有高形变能和耐酸蚀性,以适应使用环境的要求.JFE钢铁公司在第二代厚板加速冷却装置Super-OLAC(超级在线加速冷却)和感应加热型在线热处理工艺HOP(在线热处理工艺)的基础上,采用先进的材质控制技术,开发出各种高性能管线商品.本文介绍了近年来开发的管线用高性能UOE钢管的特性和生产技术.