Tracking mobile users in wireless networks via semi-supervised colocalization

Recent years have witnessed the growing popularity of sensor and sensor-network technologies, supporting important practical applications. One of the fundamental issues is how to accurately locate a user with few labeled data in a wireless sensor network, where a major difficulty arises from the need to label large quantities of user location data, which in turn requires knowledge about the locations of signal transmitters or access points. To solve this problem, we have developed a novel machine learning-based approach that combines collaborative filtering with graph-based semi-supervised learning to learn both mobile users' locations and the locations of access points. Our framework exploits both labeled and unlabeled data from mobile devices and access points. In our two-phase solution, we first build a manifold-based model from a batch of labeled and unlabeled data in an offline training phase and then use a weighted k-nearest-neighbor method to localize a mobile client in an online localization phase. We extend the two-phase colocalization to an online and incremental model that can deal with labeled and unlabeled data that come sequentially and adapt to environmental changes. Finally, we embed an action model to the framework such that additional kinds of sensor signals can be utilized to further boost the performance of mobile tracking. Compared to other state-of-the-art systems, our framework has been shown to be more accurate while requiring less calibration effort in our experiments performed on three different testbeds.     

DNA immobilization and SAW response in ZnO nanotips grown on LiNbO3 substrates.

DNA immobilization enhancement is demonstrated in a structure consisting of ZnO nanotips on 128 degrees Y-cut LiNbO3. The ZnO nanotips are grown by metalorganic chemical vapor deposition (MOCVD) on the top of a SiO2 layer that is deposited and patterned on the LiNbO3 SAW delay path. The effects of ZnO nanotips on the SAW response are investigated. X-ray diffraction and scanning electron microscopy are used to analyze the ZnO nanotips, which are of single crystalline quality, and they are uniformly aligned with their c-axis perpendicular to the substrate surface. The photoluminescence (PL) spectrum of the ZnO nanotips shows strong near bandedge transition with insignificant deep level emission, confirming their good optical property. DNA immobilization enhancement is experimentally validated by radioactive labeling tests and SAW response changes. The ZnO nanotips enhance the DNA immobilization by a factor of 200 compared to ZnO film with flat surface. DNA hybridization with complementary and noncomplementary second strand DNA oligonucleotides is used to study the selective binding of the structure. This device structure possesses the advantages of both traditional SAW sensors and ZnO nanostructures.     

Study of hybrid optical burst networks

We propose the hybrid optical burst switching (HOBS), and investigate the HOBS-based ring topology with numerical simulation. Results indicate that the packet loss ratio in HOBS is much less than that in optical burst switching(OBS) and its performance depends on some parameters such as the packet proportion, the electronic buffer size and the processing speed in the node. __________ Translated from Journal on Communications, 2005, 26(11): 7–11 (in Chinese)     

500kV曲北甲线误跳闸事故分析

本文针对500kV曲北甲线线路开关由于厂家二次接线错误而引起跳闸事故,分析其产生原因并提出防范措 施。     

我国空气中氡及其短寿命子体产生的照射

本文收集、分析和研究了我国已发表的空气中氡及其短寿命子体的资料。室外和室内^222Rn浓度按人口加权平均值的典型值分别为14Bq.m^-3和24Bq.m^-3。省市室外平均值最高和最低值相差约12倍，室内相差约6倍。室内和室外最高的都是福建。室外最低的是台湾，室内最低的是吉林。室内钍射气子体引起的照射值得引起注意，其中特别是以泥土为墙体的建筑物，在很多情况下钍射气子体所致年有效剂量高于(有时甚至远高于)氡及其子体所产生的剂量。     

"辐射防护体系演进"中一些问题的讨论

从中国辐射防护的实践看，现行辐射防护体系进行适当简化和更加协调一致是必要的。仅仅基于保护人的防护举措不是在各种情况下均能满足环境的要求。辐射防护的含意应该包括保护环境免受电离辐射的影响。集体剂量是一个有用的但需要明确其应用范围的指标。它的应用有利于促进辐射防护水平的提高，但应明确其应用的条件，如时间和空间等。天然辐射是人类所受照射的最大来源。有必要控制天然辐射产生的职业照射，如地下矿工和航空机组人员。加强控制人工辐射和天然辐射对孕妇和儿童的照射是重要的，其中特别是放射诊断和治疗。     

Development of grain boundary allotriomorphic ferrite/granular bainite duplex steel

A new hot-rolled low alloy high strength steel with grain boundary allotriomorphic ferrite/granular bainite duplex micro-structure has been developed through novel microstructure and alloying designs without any noble metal elements such as nickel and molybdenum. Its as-rolled microstructure and mechanical properties, fatigue crack propagation behavior compared with single granular bainitic steel as well as continuous cooling transformation, were investigated in detail. The measured result of CCT (continuous cooling transformation) curve shows that such duplex microstructure can be easily obtained within a wide air-cooling rate range. More importantly, this duplex microstructure has much better combination of toughness and strength than the single granular bainite microstructure. It is found that the grain boundary allotriomorphic ferrite in this duplex microstructure can blunt the rni-crocrack tip, cause fatigue crack propagation route branching and curving, and thus it increases the resistance to fati     

HL-2A Tokamak Edge Modeling with B2

The outer divertor plasma of HL-2A and its associated scrape-off plasma have been simulated using a two-dimensional multi-species fluid code of Braams with a simplified neutral gas model. HL-2A has a double-null closed divertor in separate divertor chambers above and below the nearly circular plasma tours. The computed numerical grid is developed according to an ideal magnetic surface. The calculation is involved only with pure hydrogen plasma. The emphasis has been focused on parametric studies involving variation of the assumptions made for the core plasma. The peak temperatures and the heat flux near the target are of the principal concern。     

一种新型的大功率电镀电源

国内生产的１０００Ａ以上的晶闸管与同容量二极管的价格相近，采用晶闸管研制出一种整流和控制结合为一体的大功率电镀电源，打破了传统的整流和控制分离而使用两种半导体器件及两种电磁部件的方法．这种新型的大功率电镀电源的特点是造价低，输出电流能力强，可靠性高，控制特性好且能量损失小．     

空气离心式离合器主要结构参数的确定

以传递和扭矩和工作转速为设计条件，推导并建立了空气离心式离合器的承载能力方程式及其求解方法，并在此基础上提出了确定该种离合器主要结构参数的具体设计方法和步骤。使其更便于在实际中推广和应用。