Tracking employment shocks using mobile phone data

Can data from mobile phones be used to observe economic shocks and their consequences at multiple scales? Here we present novel methods to detect mass layoffs, identify individuals affected by them and predict changes in aggregate unemployment rates using call detail records (CDRs) from mobile phones. Using the closure of a large manufacturing plant as a case study, we first describe a structural break model to correctly detect the date of a mass layoff and estimate its size. We then use a Bayesian classification model to identify affected individuals by observing changes in calling behaviour following the plant''s closure. For these affected individuals, we observe significant declines in social behaviour and mobility following job loss. Using the features identified at the micro level, we show that the same changes in these calling behaviours, aggregated at the regional level, can improve forecasts of macro unemployment rates. These methods and results highlight promise of new data resources to measure microeconomic behaviour and improve estimates of critical economic indicators.     

Tolerance optimization of a mobile phone camera lens system

In the manufacturing process for the lens system of a mobile phone camera, various types of assembly and manufacturing tolerances, such as tilt and decenter, should be appropriately allocated. Because these tolerances affect manufacturing cost and the expected optical performance, it is necessary to choose a systematic design methodology for determining optimal tolerances. In order to determine the tolerances that minimize production cost while satisfying the reliability constraints on important optical performance indices, we propose a tolerance design procedure for a lens system. A tolerance analysis is carried out using Latin hypercube sampling for evaluating the expected optical performance. The tolerance optimization is carried out using a function-based sequential approximate optimization technique that can reduce the computational burden and smooth numerical noise occurring in the optimization process. Using the proposed design approach, the optimal production cost was decreased by 28.3% compared to the initial cost while satisfying all the constraints on the expected optical performance. We believe that the tolerance analysis and design procedure presented in this study can be applied to the tolerance optimization of other systems.     

WCDMA手机音频测试

为了保证手机的音频性能符合测试标准,使用户对手机通话语音的发送和接收质量感到满意,同时还要保证手机扬声器的语音不能对使用者,尤其是对人耳造成伤害,因此就要对手机的各项语音性能进行检验,保证手机的音频电路的质量和工作正常.探讨了使用R&S公司的音频测试系统、3GPP 1326.132测试规范对手机进行测试的测试项目和测试方法,分析了不同音频测试标准的区别.并提出一些解决音频测试失败项的方法,经验表明这些方法是非常有效的.     

Toxicity characterization of waste mobile phone plastics

Waste plastic housing units (N=60) of mobile phones (of different models, and brands), were collected and analyzed for lead, cadmium, nickel and silver using atomic absorption spectrophotometry after acid digestion using a 1:1 mixture of H2SO4 and HNO3. The mean (+/-S.D.) and range of the results are 58.3+/-50.4mg/kg (5.0-340mg/kg) for Pb, 69.9+/-145mg/kg (4.6-1005mg/kg) for Cd, 432+/-1905mg/kg (5.0-11,000mg/kg) for Ni, and 403+/-1888mg/kg (5.0-12,500mg/kg) for Ag. Approximately 90% of the results for the various metals were < or =100mg/kg. Results greater than 300mg/kg were generally less than 7% for each metal and could be attributed to exogenous contamination of the samples. These results suggest that there may not be any immediate danger from end-of-life (EoL) mobile phone plastic housing if appropriately treated/managed. However, considering the large quantities generated and the present low-end management practices in most developing countries, such as open burning, there appears a genuine concern over the potential for environmental pollution and toxicity to man and the ecology.     

Recall of past use of mobile phone handsets

Previous studies investigating health effects of mobile phones have based their estimation of exposure on self-reported levels of phone use. This UK validation study assesses the accuracy of reported voice calls made from mobile handsets. Data collected by postal questionnaire from 93 volunteers was compared to records obtained prospectively over 6 months from four network operators. Agreement was measured for outgoing calls using the kappa statistic, log-linear modelling, Spearman correlation coefficient and graphical methods. Agreement for number of calls gained moderate classification (kappa = 0.39) with better agreement for duration (kappa = 0.50). Log-linear modelling produced similar results. The Spearman correlation coefficient was 0.48 for number of calls and 0.60 for duration. Graphical agreement methods demonstrated patterns of over-reporting call numbers (by a factor of 1.7) and duration (by a factor of 2.8). These results suggest that self-reported mobile phone use may not fully represent patterns of actual use. This has implications for calculating exposures from questionnaire data.     

揭秘手机“监听卡”骗局

"想监听老公(老婆)在你背后做什么?手机监听卡帮您圆梦。"您是否收到过类似的短信呢?所谓的"监听卡"真的能监听到吗?记者以客户的身份了解到,货倒是可以"货到付款",但是卡不能直接用,必须在交上钱以后,才能告诉你"密码"。看不到发荣誉证书的单位记者首先联系到的是一家"华阳商务软件调查有限公司",网页上有产品介绍、功能说明、使用说明和产品价格等内容,其中在功能说明中介绍,     

Driver hand-held mobile phone use and safety belt use

The purposes of the study were to identify hand-held mobile phone use trends for Michigan and to compare safety belt use between users and nonusers. Mobile phone and safety belt use was investigated by a direct observation survey of drivers at intersections in Michigan. Data were weighted to calculate mobile phone use and safety belt use rates statewide. The study showed 2.7% of Michigan drivers were using a mobile phone at any given daylight time. Safety belt use of current mobile phone users was significantly lower than those not using mobile phones.     

基于知识的车载LiDAR地物自动分类

车载LiDAR已广泛应用于三维数字城市建模、道路信息数据采集等领域。海量点云信息中不同地物目标的自动识别和分类是LiDAR数据后处理的难点之一。本文根据不同地物目标物理特性、空间拓扑关系及其在点云中的相关特征知识,建立地物分类规则,依据分类知识进行地物自动识别和分类。通过实测数据分类试验,证明该方法可以较好实现建筑物、树木、线杆、行人等不同地物的自动识别和分类。     

Deriving a context

A framework for focussig discussion is built upon past events and present concerns. What happened about design thinking in the past is partly mythical and partly obtained from writings of the time and recent accounts by participants. Present concerns are largely about ‘wholeness’, the nature of design, and how best to teach it. Models form a principal part of design problem-solving. The application of computers and better use of human response offer directions for improvement of design activity. Each can be facilitated through richer models of designing. Are such available and are there any problems which arise? Can computers and human response be fruitfully coupled?     

Applicability of an exposure model for the determination of emissions from mobile phone base stations

Applicability of a model to estimate radiofrequency electromagnetic field (RF-EMF) strength in households from mobile phone base stations was evaluated with technical data of mobile phone base stations available from the German Net Agency, and dosimetric measurements, performed in an epidemiological study. Estimated exposure and exposure measured with dosemeters in 1322 participating households were compared. For that purpose, the upper 10th percentiles of both outcomes were defined as the 'higher exposed' groups. To assess the agreement of the defined 'higher' exposed groups, kappa coefficient, sensitivity and specificity were calculated. The present results show only a weak agreement of calculations and measurements (kappa values between -0.03 and 0.28, sensitivity between 7.1 and 34.6). Only in some of the sub-analyses, a higher agreement was found, e.g. when measured instead of interpolated geo-coordinates were used to calculate the distance between households and base stations, which is one important parameter in modelling exposure. During the development of the exposure model, more precise input data were available for its internal validation, which yielded kappa values between 0.41 and 0.68 and sensitivity between 55 and 76 for different types of housing areas. Contrary to this, the calculation of exposure-on the basis of the available imprecise data from the epidemiological study-is associated with a relatively high degree of uncertainty. Thus, the model can only be applied in epidemiological studies, when the uncertainty of the input data is considerably reduced. Otherwise, the use of dosemeters to determine the exposure from RF-EMF in epidemiological studies is recommended.     

光学测量方法在手机跌落测试中的应用

手机跌落试验主要用于检验手机质量,有限元分析模拟仿真方法能够帮助厂家在产品开发阶段优化手机结构,但不能对成品实物进行质量检验。针对上述问题,该文提出一种基于光学测量的手机跌落试验方法,采用双目立体视觉原理,利用摄影测量技术,提高数字图像相关法匹配精度,使用高速相机对手机跌落过程进行连续采集,提高系统标定精度后通过图像数据计算分析获取手机跌落过程中的全场位移及应变值。该文用华为荣耀4A手机前壳进行试验,成功获取其跌落过程中的三维全场变形数据,证明基于数字图像相关法手机跌落试验方法具有高精度、试验过程简便等优点,满足成品手机质量检测的需求。     

基于反卷积的手机屏下成像图像恢复

随着全面屏手机的发展,手机屏下成像的研究应运而生。但由于手机屏幕存在电路走线和其他不透明部分,光通过屏幕会产生衍射,降低成像结果的图像质量,本文从图像复原的角度,对屏下相机拍摄的图像进行恢复。通过测量得到手机成像系统的点扩散函数(PSF),利用测得的PSF,对图像进行反卷积处理。本文改进了传统的反卷积方法,对原始图像进行颜色空间转换,然后对不同的通道分别处理。相较于传统反卷积方法,改进后的反卷积方法得到的处理结果在结构相似度(SSIM)、峰值信噪比(PSNR)等指标上都有提高,运行时间更短。在分通道反卷积之后,使用非局部平均算法进行去噪处理,进一步提高了屏下图像的质量。     

Pedestrian injuries due to mobile phone use in public places

Research shows that pedestrians, similar to drivers, experience reduced situation awareness, distracted attention and unsafe behavior when talking or texting on their mobile phones. The present study centered on injuries related to mobile phone use among pedestrians. It used data from the US Consumer Product Safety Commission on injuries in hospital emergency rooms from 2004 through 2010. It found that mobile-phone related injuries among pedestrians increased relative to total pedestrian injuries, and paralleled the increase in injuries for drivers, and in 2010 exceeded those for drivers. Pedestrian injuries related to mobile-phone use were higher for males and for people under 31 years old. Using a mobile phone while walking puts pedestrians at risk of accident, injury or death.     

充电器对移动电话比吸收率影响的研究

阐述电磁波对人体的影响可测试参数比吸收率的定义、测试方法和测试系统,分析影响移动电话比吸收率的主要因素,重点研究移动电话附件充电器对移动电话比吸收率的影响,提出充电器对移动电话的等效天线影响模型,并通过实际的测试数据来验证模型.基于模型提出降低充电器对移动电话比吸率影响的改进措施,为移动电话设计提供参考依据.     

安全RFID与NFC手机的互动防伪应用

随着射频识别技术（RFID）技术的发展与成熟,RFID技术其远距离识别、存储量大、标签唯一编码标识、环境适应性强等技术优势,逐步在溯源防伪领域取得了应用和推广。伴随移动互联网的高速发展,智能手机已经逐步成为人们接触外界信息的最主要设备,被称为个人感官的延伸。将NFC智能手机与RFID技术结合,应用于溯源防伪领域,具备很好的应用前景。     

On the diffusion of mobile phone innovations for financial inclusion

This article investigates nexuses between innovations in mobile money and financial inclusion. Demand and supply factors that affect the diffusion of mobile services as well as macro-level institutional and economic factors are taken in account. The focus is on 148 countries with data mostly consisting of 2010–2014 averages. The empirical evidence is based on Tobit regressions. The study finds that when the empirical analysis is robust to multicollinearity, two main tendencies are apparent: the significant findings of Lashitew et al. (2019) [1] are confirmed and many new significant estimated coefficients emerge. While this study confirms the findings of the underlying research, it also goes further to improve the harmony in narratives between the predictors and the outcome variables. Accordingly, by accounting for multicollinearity, the earlier findings are now more consistent across the set of predictors (i.e. demand and supply factors) and the attendant financial inclusion outcomes (i.e. mobile money accounts, mobile used to send money and mobile used to receive money).     

Deriving an estimate for the Fried parameter in mobile optical transmission scenarios

Measuring the Fried parameter r(0) (atmospheric optical coherence length) in optical link scenarios is crucial to estimate a receiver's telescope performance or to dimension atmospheric mitigation techniques, such as in adaptive optics. The task of measuring r(0) is aggravated in mobile scenarios, when the receiver itself is prone to mechanical vibrations (e.g., when mounted on a moving platform) or when the receiver telescope has to track a fast-moving signal source, such as, in our case, a laser transmitter on board a satellite or aircraft. We have derived a method for estimating r(0) that avoids the influence of angle-of-arrival errors by only using short-term tilt-removed focal intensity speckle patterns.     

Impact of mobile phone use on car-following behaviour of young drivers

Multitasking, such as the concurrent use of a mobile phone and operating a motor vehicle, is a significant distraction that impairs driving performance and is becoming a leading cause of motor vehicle crashes. This study investigates the impact of mobile phone conversations on car-following behaviour. The CARRS-Q Advanced Driving Simulator was used to test a group of young Australian drivers aged 18–26 years on a car-following task in three randomised phone conditions: baseline (no phone conversation), hands-free and handheld. Repeated measure ANOVA was applied to examine the effect of mobile phone distraction on selected car-following variables such as driving speed, spacing, and time headway. Overall, drivers tended to select slower driving speeds, larger vehicle spacings, and longer time headways when they were engaged in either hands-free or handheld phone conversations, suggesting possible risk compensatory behaviour. In addition, phone conversations while driving influenced car-following behaviour such that variability was increased in driving speeds, vehicle spacings, and acceleration and decelerations. To further investigate car-following behaviour of distracted drivers, driver time headways were modelled using Generalized Estimation Equation (GEE). After controlling for various exogenous factors, the model predicts an increase of 0.33 s in time headway when a driver is engaged in hands-free phone conversation and a 0.75 s increase for handheld phone conversation. The findings will improve the collective understanding of distraction on driving performance, in particular car following behaviour which is most critical in the determination of rear-end crashes.     

1300万像素手机镜头设计

为满足高像素手机的要求,本文根据光学成像理论,利用code V软件设计出一种1300万像素手机镜头。为了增加自由度,减小像差,得到更好的像质,本文采用非球面表面进行光学设计。该镜头由五片非球面镜片、一片滤光镜组成。设计得到光圈值2.2,半视场角35°,有效焦距3.6 mm,镜头总长3.6 mm的轻薄型手机镜头。最终中心视场在中间频率处(即223 lp/mm)的MTF值大于0.6,在高频处大于0.2,在0.8视场中频MTF值大于0.4,可见优化完毕后成像效果可满足使用要求。