Simulation of MIMO channel characteristics for indoor visible light communication with LEDs

In order to study the characteristics of multiple input and multiple output (MIMO) channel, first, the basic components of the communication system are analyzed. And then, we present a simplified ray tracing method for optical MIMO system to obtain its channel impulse response and frequency response. This method using ray tracing to calculate the impulse of the channel limits the reflections within three times. Finally, its validity is verified by the numerical simulations, and its simulation results have been discussed. The channel bandwidth is gradually narrow, direct response is getting small, and the first response becomes large from the center to the corner.     

Mobile phone tower location for survival after natural disasters

This paper discusses the location or strengthening of cell phone towers so as to maximize service coverage and minimize the loss of communications if a natural disaster happens. This paper demonstrates that, under a high likelihood of destruction of antennas (towers), the customary method of maximizing coverage provides poor solutions as compared to the proposed method. In addition to the maximization of service coverage, the objectives of our model include the minimization of expected and worst-case losses. The model is applied to a region in the south of Chile that was stricken by one of the most destructive earthquakes registered in history. Computational results are provided for a variety of scenarios.     

Towards the acoustical characterisation of an Intensive Care Unit

Intensive Care Units (ICUs) can be immensely noisy places, where high noise levels may have deleterious effects on patients, visitors and staff alike. Many studies have identified sound levels exceeding World Health Organisation’s recommendations, although very few measured for more than 24 h or concurrently in multiple locations, as normally done in outdoor studies. In order to assess the feasibility of installing a continuous monitoring system in the indoor environment of an 18 bedded general intensive care, a MEMS-based microphone was used to monitor the noise levels for 7 days. Results showed minimal variation between night and day, but changes in sound level could be correlated with regularly occurring activities. The impact of microphone-holding structure on the measurements and the possibility of inferring patient and visitor’ exposure from a fixed measurement position are also discussed. Laboratory analysis, confirmed by in situ testing, identified ideal microphone positioning, and led to a correction of −1 dB for the sound pressure level measured at the microphone to obtain the level experienced by the patient.     

TD-LTE海面超远距离覆盖研究与测试

为验证TD-LTE网络的覆盖能力,本文重点分析特殊参数配置（特殊子帧配置、Preamble格式）、天馈有效高度等对TD-LTE超远距离覆盖的影响,并结合频段选用、覆盖增强技术等对海面场景超远覆盖技术方案进行了深入探讨,依据实际测试情况进行分析和总结。     

Coverage performance analysis of multi-camera networks based on observing reliability model

Coverage control is a fundamental problem in sensor networks, which has been explored thoroughly based on a traditional scalar sensing model. However, camera sensors are different from traditional scalar sensors as different cameras from different positions can form distinct views of the target. Hence, Target size and geometric structure of camera nodes can greatly influence the surveillance ability of a camera network. In view of this, a novel observation reliability model of a camera network is proposed, and relationship between surveillance ability and observing reliability for the target is studied. On the basis, a camera network coverage model which considers about obstacles and interesting area of the environment is investigated, and optimized by dynamic planning method. Simulation results show that our method can effectively improve the target capture rate of the network and also we can observe the target from a better view.     

功能点分析方法在银行软件外包项目管理中的研究与应用

本文首先介绍了软件功能点分析方法在外包项目管理中的重要性.结合银行系统外包项目的特点,提出了通过软件功能点分析方法,对外包项目工作量、软件生产率、缺陷密度、测试用例覆盖率的估算.借鉴PMBOK、CMM/CMMI、IS0 9001等理论,搭建基于功能点分析测量标准流程和方法,从而更好地对外包项目进行管理.以银行系统外包项目管理为例,验证分析其有效性.     

可见光响应碳掺杂的光催化剂涂覆于塞流反应器上分解气态芳香化合物(英文)

A plug‐flow reactor coated with carbon‐doped TiO2 (C‐TiO2 ) powder was investigated for the control of vaporous aromatics (benzene, toluene, ethylbenzene, and o‐xylene (BTEX)) under a range of experimental conditions. The characteristics of the as‐prepared C‐TiO2 and a reference Degussa P25 TiO2 powder were examined using X‐ray diffraction, scanning electron microscopy, diffuse‐reflectance ultraviolet‐visible‐near infrared spectroscopy, and Fourier transform infrared spectroscopy. The experimental conditions for the photocatalytic performance of the as‐prepared C‐TiO2 photocatalyst were controlled using three operational parameters, relative humidity, flow rate, and input concentration. Unlike other target compounds, very little benzene was removed by the C‐TiO2 photocatalyst under visible‐light irradiation. In contrast, the C‐TiO2 exhibited higher removal efficiencies for the other three target compounds (toluene, ethylbenzene, and xylene) compared with those achieved using unmodified TiO2 under visible‐light irradiation. The highest removal efficiency was obtained at a relative humidity value of 45%. Specifically, the toluene removal efficiency determined at a relative humidity of 45% was 78%, whereas it was close to 0%, 7.2%, and 5.5% for relative humidity values of 20%, 70%, and 95%, respectively. In addition, the removal efficiencies for the three target compounds decreased as the flow rate or input concentration increased. These findings indicate that the as‐prepared C‐TiO2 photocatalyst could be used for the removal of toxic vaporous aromatics under optimized operating conditions.     

Development of a highly sensitive method for determining atmospheric carbonyl compounds by passive sampling and application of the method to a survey of indoor air

A simple, highly sensitive analytical method for measuring many kinds of carbonyls in air using a passive sampler containing a sorbent (silica gel) coated with 2,4-dinitrophenylhydrazine has been developed. The carbonyls collected by the sampler were extracted with a solvent, and the extracts were subjected to high-performance liquid chromatography (HPLC; UV detection) without first being concentrated. In this method, the volume injection is examined, and is found to have a sensitivity at least 20 times that of ordinary HPLC methods. The air concentrations of nine carbonyls collected by passive sampling over a period of 24?h were estimated by means of conversion equations derived from the results of active sampling;c?=?^{10[log ( y} )^{??? b ] a} , where c is the carbonyl concentration in air (µg/m³); y is the amount of carbonyl collected by the passive sampler (µg); and a and b are constants for each carbonyl compound. The calculated air concentrations were consistent with the concentrations measured by active sampling. This method may be useful in determining personal exposure to ambient carbonyls.     

A review of: “Potential Industrial Carcinogens and Mutagens,Studies in Environmental Science 4 by Lawrence Fishbein,Little Rock,Arkansas, 534 pages,many figures and tables,linen, format 250 × 175 mm,printed by Elsevier Scientific Publishing Company,Amsterdam, The Netherlands 1979, 73.25 US$ or 150.-Df1.”

Abstract

The design and calibration of a passive sampler operating according to the diffusion principle and its application to the analysis of indoor air are described. Taking aliphatic and aromatic hydrocarbons as representative pollutants, it is demonstrated that at constant concentration, the amount of substance trapped by the sampler is a linear function of the time of exposure. An equation is given relating this amount of substance to the mean pollutant concentration. The detection limit is of an order of 300μg/(m³.h). For test gas atmospheres variation coefficients of between 5 and 10%, were determined for a 24-hour exposure in an atmosphere with concentrations of the individual hydrocarbons between 150 and 600 μg/m³.