空户的影响与处理——绘图列举抽样田野工作笔记

当前中国的人口流动状况导致全国代表性入户抽样调查,不得不使用绘图列举抽样技术。虽然实地绘制住户地图、列举住户,相比通过户籍登记信息建立社区住户抽样框的方式更为贴近实际,但这也可能引入过多"空户",从而导致过度列举。这既可能导致抽样权数偏高,也会带来样本膨胀问题。本文建议通过调整抽样调查方法,估算样本膨胀系数,扩大社区住户样本规模,进而缓解基本权数偏高的问题。

A spectrum hole detection mechanism in cognitive radio networks applied in typical scenarios

A novel spectrum hole detection mechanism is proposed to improve the detection probability in cognitive radio networks for several typical scenarios. By removing the influence of the spatial false alarm （SFA）, the spectrum hole detection probability of the secondary user under path loss and multi-path fading is derived. Meanwhile, the spectrum hole detection probability of multi-users cooperative sensing and that of single-user sensing in multi-bands are derived for comparison. Theoretical analyses and simulation results show that the spectrum hole detection probability of the proposed mechanism is inversely proportional to the sampling times and the area of the sensing region. The detection performance of the multi-users sensing is better than that of single-user sensing when with the AND ~ogic fusion rule but worse when with the OR logic fusion rule. The detection probability is further decreased in the Rayleigh fading channel but it is greatly increased in multi-bands.

Web multimedia information retrieval using improved Bayesian algorithm

The main thrust of this paper is application of a novel data mining approach on the log of user' s feedback to improve web multimedia information retrieval performance. A user space model was constructed based on data mining, and then integrated into the original information space model to improve the accuracy of the new information space model. It can remove clutter and irrelevant text information and help to eliminate mismatch between the page author' s expression and the user' s understanding and expectation. User spacemodel was also utilized to discover the relationship between high-level and low-level features for assigning weight. The authors proposed improved Bayesian algorithm for data mining. Experiment proved that the au-thors' proposed algorithm was efficient.

Research on Services Modeling in LTE Networks

Service modeling offers fundamental guidance to the construction and operation of mobile telecommunication networks. As the domestic LTE networks have been deployed massively, the refined LTE services model needs to be established urgently. In this paper, we firstly extract characteristic parameters of services from statistical data in 3G networks, especially in time, space and user dimension. Secondly, the development trends of LTE services are analyzed. And the refined LTE service model is established. Finally, prediction results of LTE service development in China is given, which could provide effi cient support for networks' optimization and evolution.

Joint User Scheduling and Antenna Selection in Distributed Massive MIMO Systems with Limited Backhaul Capacity

Massive MIMO systems offer a high spatial resolution that can drastically increase the spectral and/or energy efficiency by employing a large number of antennas at the base station(BS).In a distributed massive MIMO system,the capacity of fiber backhaul that links base station and remote radio heads is usually limited,which becomes a bottleneck for realizing the potential performance gain of both downlink and uplink.To solve this problem,we propose a joint antenna selection and user scheduling which is able to achieve a large portion of the potential gain provided by the massive MIMO array with only limited backhaul capacity.Three sub-optimal iterative algorithms with the objective of sumrate maximization are proposed for the joint optimization of antenna selection and user scheduling,either based on greedy fashion or Frobenius-norm criteria.Convergence and complexity analysis are presented for the algorithms.The provided Monte Carlo simulations show that,one of our algorithms achieves a good tradeoff between complexity and performance and thus is especially fit for massive MIMO systems.

Selective transmission and channel estimation in massive MIMO systems

Massive MIMO systems have got extraordinary spectral efficiency using a large number of base station antennas,but it is in the challenge of pilot contamination using the aligned pilots.To address this issue,a selective transmission is proposed using time-shifted pilots with cell grouping,where the strong interfering users in downlink transmission cells are temporally stopped during the pilots transmission in uplink cells.Based on the spatial characteristics of physical channel models,the strong interfering users are selected to minimize the inter-cell interference and the cell grouping is designed to have less temporally stopped users within a smaller area.Furthermore,a Kalman estimator is proposed to reduce the unexpected effect of residual interferences in channel estimation,which exploits both the spatial-time correlation of channels and the share of the interference information.The numerical results show that our scheme significantly improves the channel estimation accuracy and the data rates.

SPATIAL COMPATIBLE USER GROUPING ALGORITHM FOR MULTIUSER MIMO SYSTEMS

A spatial compatible user grouping algorithm is proposed to reduce CoChannel Interference (CCI) in Space Division Multiple Access (SDMA) multiuser Multiple Input Multiple Output (MIMO) systems. We evaluate the interferences among users by use of distances between row spaces spanned by users’ channel matrixes, then control frequency sharing according to the compatible user grouping algorithm. Results show that the row space distance algorithm outperforms others because it can fully utilize the information from users’ channel matrixes, especially the matrix structure information. The results also prove that the algorithm based on channel matrix structure analysis is a better candidate for spatial compatibility approximation.

Cyber Spatiotemporal as Media Culture： A Cognitive Level Study of Time （Tempo） and Space （Spatial） Based on Media Types

This research explores media users＇ cognition of ＂time＂ and ＂space＂ across different media platforms, and conducts a comparison among media genres including mass media and intemet media based on user＇s interactivities. Especially, this research focused on the internet＇s space and time perception based on communication genres such as e-mail, Blogs, portals, news-media, e-commerce, and social media （SNS）. The research adopted two theories （construal level theory of time and space）. The time related theory is ＂temporal distance theory＂. The space related theory is ＂media space＂. The research is designed to measure user＇s perception of interactivity, time-construal level and its media space cognition while using the media. There are two independent variables： Interactivities （contents, user, and media levels） and user involvement （CMC-user vs. user, HCI-user vs. media）; there are two dependent variables： Cognition of spatial and temporal levels. This research also seeks the associated variables relationship among those variables through the structural equation model （SEM）. The 307 data was collected and analyzed to test the research question. The results show that the dimension of the media side＇s interactivity affected media＇s usage time and space perception. There are 2 ~ 2 factors variables to affect time and space. One is human and media interaction （HC1） and human to human communication （CMC）; the other is traditional mass media （one-way communication） and interuet media （two-ways communication）. The results prove the user＇s perception for media time and space is based on the levels of interactivity. The levels of interactivities depend on media usage： one-one, one-many, synchronous, asynchronous, interpersonal, and social network communication. Online media provides greater social space; while traditional media tends toward para-space perception. On the other hand, the users＇ time cognitions between online media are different such as fixed time versus cyber-time.

Improved Prefix Based Format-Preserving Encryption for Chinese Names

In the era of big data, government, business and personal digital information will be possible for data mining. Data mining requires massive data as a support. However, the direct release of the original mass data, which usually contain some sensitive information of personal or analysis, will result in leakage of user privacy. Therefore, it is becoming increasingly important to protect privacy information in data publishing. In this paper, we focus on the multi-type self-identified format-preserving encryption. First, we introduce a multi-type self-identified format-preserving encryption system and discuss the encryption of various types of data in this system. Then, for the format preserving encryption(FPE) about Chinese name, we study from the encryption model construction and basic encryption scheme. The format-preserving encryption model about Chinese name is constructed and the concept of the name library is presented. Based on this, it is used to not only limit the message space to reduce complexity, but also ensure the cipher in accordance with the Chinese naming habits. In addition, according to the encryption and decryption model, format-preserving encryption process of Chinese name is designed. In order to add new names, the algorithm of name space expansion is proposed. Based on the Prefix, this paper put forward an algorithm named Cycle-Prefix, which enhances the security and dynamics of FPE by using two adjustment factors and the circular encryption. Compared with the traditional Prefix algorithm, experiments show that Cycle-Prefix can not only complete the task of FPE for Chinese name, but also encrypt same plain text into different ciphers under the premise of similar efficiency with Prefix.

INTERFERENCE SUPPRESSING FOR CELLULAR MIMO SYSTEM BASED ON TURBO RECEIVER

Space-Time Coding （STC）, which combines channel coding, modulation, and multiple transmit antennas, is a powerful scheme to achieve higher data rates and combat fading in wireless systems, in this paper, we propose a soil/cancellation turbo equalization scheme to suppress Co-Channel Interference （CCI） in STC systems. The simulation results show that the proposed method significantly improves the system＇s ability of interference suppression, while preserving the space-time structure.

Case study of debris flow disaster scenario caused by torrential rain on Kiyomizu-dera, Kyoto, Japan - using Hyper KANAKO system

This paper presents debris-flow numerical simulations using the Hyper KANAKO system,developed by the authors.The system uses the debris flow simulator KANAKO 2D equipped with a graphical user interface(GUI);hence,a user can easily produce appropriate landform data for simulations using standard laser profiler data,and visualize the results using a GIS.Hyper KANAKO was applied to the streams around Kiyomizu-dera in Kyoto,Japan.Kiyomizu-dera is a famous temple in Japan which is visited by numerous tourists throughout the year.We simulated a disaster scenario of debris flow caused by torrential rain.We set the hydrograph using rainfall intensity data,and set the landform data using information from the Geospatial Information Authority of Japan(GSI) and a digital elevation model(DEM).We evaluated different mesh sizes and also used a digital surface model(DSM) to consider the building heights.The simulation results showed that with small mesh size,the debris flowmoved through the roads,which seems realistic for a disaster situation.When buildings were considered,the flow direction changed,and a 1-m flow depth,which was deeper than in other cases,appeared in the flow path.This may pose a dangerous situation for evacuations.

BLIND DETECTION FOR MULTI-RATE DS-CDMA SYSTEM WITH ANTENNA ARRAY AT THE BASE STATION

In this paper, we propose the blind space-time high rate multi-user detector for synchronous uplink multi-rate Direct Sequence Code Division Multiple Access （DS-CDMA） systems with antenna array at the base station. By employing antenna array at the base stations, the spatial dimension is used efficiently to suppress co-channel interference and increase the capacity for multi-rate CDMA system. After low rate physical users in the system are modeled as corresponding high rate virtual users, we construct the space-time signature vectors of virtual users. And subspace projection algorithm is employed to estimate space-time signature vectors blindly. Then a soft-decision high rate lnultiuser detector is proposed based on the estimated signature vectors, which avoids estimating the ambiguous complex factors which are necessary in traditional blind detector. Numerical simulation results evaluate the performance in terms of Bit Error Rate （BER） for the proposed scheme. Simultaneously, it demonstrates that the system capability increases two times when using twoelement antenna array.

Interference Alignment Based on Subspace Tracking in MIMO Cognitive Networks with Multiple Primary Users

The interference alignment （IA） algorithm based on FDPM subspace tracking （FDPM-ST IA） is proposed for MIMO cognitive network （CRN） with multiple primary users in this paper. The feasibility conditions of FDPM-ST IA is also got. Futherly, IA scheme of secondary network and IA scheme of primary network are given respectively without assuming a priori knowledge of interference covariance matrices. Moreover, the paper analyses the computational complexity of FDPM-ST IA. Simulation results and theoretical calculations show that the proposed algorithm can achieve higher sum rate with lower computational complexity.

Means-End Chain Model Framework for Measuring Housing Environment Choice Behavior

Housing and housing space has been a place for personal development, recreation and self accentuation. The need for housing and housing space quality can therefore not be overemphasized. The need for housing remains a constant index for all societies through the ages. Housing is a complex and heterogeneous product in its setting, the cognitive structures of housing users for housing attributes is also complex as well as their choice behaviors. Means-End Chain （MEC） model has been found to be very effective and potent in measuring these complexities. This conceptual paper explores from literature the MEC model and attempts to propagate its use as a research model for housing research, environment-behavior studies and person-environment congruence. It also presents the methodology employed by MEC for data collection and data management. It will suggest an extension to the traditional methodology that MEC utilizes. The possibility of extending the previous methods and their applicability in design process is herein presented; and to make a case for the usability of MEC model as a research tool for housing researchers. In dealing with user preference of housing, there is a need for research for a development of a technological tool for the identification of user needs and preference, and the kind of decision support that are required to identify these needs.

Carbon Monoxide Exposure during Cooking in Households： A Case of Dares Salaam City, Tanzania

Exposure to CO （carbon monoxide） during cooking in households using LPG （liquefied petroleum gas）, natural gas and charcoal as fuels has been conducted. The study aimed at assessing the indoor air quality in order to address potential hazards associated with CO. Carbon monoxide concentrations and flame temperature were measured at an interval of 1 min for 1 h using CO and thermometer data loggers respectively. While the CO concentration from LPG and natural gas were found below 26 ppm for 1 h, as recommended by WHO （World Health Organization） standards, the average CO concentration from charcoal exceeded the standard limit. In addition closing the kitchen door during cooking increased the CO concentration from 26-295 ppm to 92-597 ppm. According to WHO, the observed CO concentrations from charcoal stove highlights questionable life support atmosphere. It can therefore be suggested that switching to LPG or natural gas from charcoal will reduce CO exposure to persons during cooking.

New Generation of Outdoor Vacuum Circuit Breakers with Rated Voltage up to 40.5 kV

The article describes design peculiarities of the novel compact vacuum circuit breaker with rated voltage 40.5 kV. The design incorporates several novel technical solutions： polycarbonate support insulation, mono-stable magnetic actuator, labyrinth pulling insulator, core-type flexible contact and new compact vacuum interrupter （VI）. Phases are encapsulated into silicone rubber providing required creepage distance and excellent tracking resistance. These novelties along with extensive modeling of the mechanical and electrical fields followed by design optimization resulted in weight reduction of more than 50% compared with alternatives available in the market. And this is in spite of built in sensors measuring： phase currents, zero-sequence current, phase voltages.

Multiuser Pre-Coding Aided Quadrature Spatial Modulation for Large-Scale MIMO Channels

Pre-coding aided quadrature spatial modulation(PQSM) is a promising multiple input multiple output(MIMO) transmission technology. The multiuser(MU) detection in PQSM system is investigated in this paper. Based on the known channel state information, pre-coding matrix is designed to pre-process the in-phase and quadrature signals of quadrature spatial modulation(QSM) to reduce the inter-channel interference. In order to lower the complexity at the receiver brought by the orthogonality of the PQSM system, an orthogonal matching pursuit(OMP) detection algorithm and a reconstructed model are proposed. The analysis and simulation results show that the proposed algorithm can obtain a similar bit error rate(BER) performance as the maximum likelihood(ML) detection algorithm with more than 80% reduction of complexity.

Value Creation for the After-Sales Services： Organizational and Strategic Perspectives

As a part of the product development process, the after-sales services are not only a source of innovation, but also they benefit from value creation through new managerial methodologies for the achievement of competitive advantage and customer satisfaction. The objective of the paper is to further understand value creation for the after-sales services. We present the case of the creation of a new business for the after-sales services for the entrance into a new market. The new business is created by two gurus in the aerospace industry. A typology of guidelines is derived, based on organizational and strategic perspectives, for the after-sales services value creation and the guidelines for the creation of a new business as well as for the entrance of into a new market are presented.

AN IMPROVED SUBSPACE TRACKING ALGORITHM FOR BLIND ADAPTIVE MULTIUSER DETECTION

As the Projection Approximation Subspace Tracking with deflation(PASTd) algorithm is sensitive to impulsive noise, an improved subspace tracking algorithm is proposed and applied to blind adaptive multi-user detection. Simulation results show that the improved PASTd algorithm not only remains the properties of the conventional PASTdalgorithm, but also has good Bit Error Rate(BER) performance in impulsive noise environment, thus it can effectively improve the system performance.

Assisting Temporal Requirement Specification

The aim of the present work is to introduce a pattern-based method for assisting the user during the temporal Requirement Specification （RS） phase. Indeed, since the user usually has to handle abstract notation as well as mathematical-based languages within this phase, RS is becoming more and more tedious and error-prone especially when dealing with complex systems. The authors＇ method begins by defining a new typology while taking into account all the common temporal requirements one may meet when specifying a system. Then, a literal word-based formal grammar able to express all the types of the identified requirements has been developed. Actually, the goal is to assist the user during the requirement identification with some means that are simple, intuitive, albeit rigorous. Finally, a generic set of observation patterns relative to the new time constraint taxonomy is defined. In practice, to check a given temporal constraint, its relative observation pattern is instantiated to obtain an observer that will stand for a watchdog for the associated requirement on the system.