Sodar observation of elevated layers around Calcutta

Abstract

Sodar (sound radar) echograms recorded at the Indian Statistical Institute, Calcutta, often exhibit stratified or elevated layers over the ground-based inversion. These have been noticed often after the occurrences of thunderstorms and rain. These layers may be single or multiple, continuous or intermittent and are associated with some perturbations even as gravity wavelike structures. All these features of the lower atmospheric structures over this coastal station, as detected by a sound radar, are discussed in this paper.     

Acoustic remote sensing of internal waves in shallow water

Abstract

Acoustic continuous-wave measurements are presented, which were carried out during June 1978 in the North Sea at a water depth of 30 m. The source was operated at a frequency of 295 Hz and the signal was recorded by two hydrophones at a distance of 1100 m south and east, respectively, from the source. The observed fluctuations of the acoustic amplitude and phase are analysed for periods from 10 min up to 2 hours and are compared with simultaneously measured currents. A theory is developed with the objective of relating the acoustic fluctuations to motions of the sea. For the considered periods and the density stratification during the experiment it is assumed that the observed currents are due to internal waves. The theoretical results agree well with the measurements.     

Evaluation of the potential of the Thematic Mapper for marine application

Abstract

The potential of the Thematic Mapper (TM) on board Landsal-5 for marine applications has been investigated with reference to the well-known performance of the Coastal Zone Color Scanner of Nimbus-7. The study consisted of (a) a sensitivity analysis, considering such fundamental error sources as retrieval algorithm sensitivity, atmospheric correclion, instrument noise and signal digitization and (b) the interpretation of a TM scene by the procedure suggested in (a). The evidence provided by the experimental test validated the positive conclusions of the theoretical work, indicating that the analysis of TM bands 1 to 4 data should be capable of yielding quantitative information of satisfactory quality on fundamental water quality parameters, such as chlorophyll (i.e. phytoplankion) and suspended sediment concentrations.     

Muscular effort and musculoskeletal disorders in piano students: electromyographic,clinical and preventive aspects

Abstract

An investigation was made on the relationship between music practice and musculoskeletal disorders among piano students, with the main aim of developing health education programmes that would improve the performance and health of the students.

The investigation covered three areas

(a) Analysis of study organization and main musculoskeletal complaints achieved by a questionnaire distributed to all piano students at the Milan Conservatory.

(b) Vocational electromyographic analysis of the effort exerted by the various muscle groups of the trunk, of the shoulder and shoulder blade girdle, and of the arm during performance of a standard set of piano exercises, an unseen passage and a passage of maximum difficulty. This analysis was made on a sample of six subjects.

(c) A series of preventive measures was developed on the basis of a critical assessment of the results (38% of the students practised for excessively long periods without breaks; 62% had from 1 to 5 complaints, the most affected sites being the spine and the trapezius muscles). These consisted largely of a health education programme aimed at helping the students to suitably organize practice and rest periods and in instructing them in appropriate exercises for relaxation and stretching of overused muscle groups and strengthening the supporting muscle groups. Changes in lifestyle were also suggested.     

A KNOWLEDGE-BASED SYSTEM FOR COURSE SCHEDULING

Abstract

A knowledge-based scheduling system has been developed for the domain of university class scheduling. The problem addressed is how to schedule courses during the various time periods throughout the day. The class schedule must satisfy a variety of appropriate constraints. The system, written in Prolog, resolves conflicting assignments through backtracking. The inefficiency of Prolog's backtracking feature, with respect to this application, is partly circumvented by the use of a dynamic circular array. The system is now being used to help schedule industrial engineering classes at the Pennsylvania State University.     

Measurement of wind across a microwave line-of-sight propagation path

Abstract

Methods of measuring wind across a microwave propagation path are examined and specific problems involved are discussed. Both the initial slope and the time-delay method are considered and the use of a filter in the time domain for changing the shape of the weighting functions is examined. An experiment that has been carried out at X-band along a 37 km propagation path over hilly terrain is described. In this experiment emphasis has been given to straightforward procedures for inferring the wind across the path by making use of simple wind models valid for some kind of air circulation. A comparison of the results with data obtained from conventional wind measurements is reported.     

A case study

Abstract

A model developed for radiative transfer in the atmosphere-sea system is applied to remotely-sensed radiances to evaluate its applicability in the determination of atmospheric turbidity. Data measured at different atmospheric turbidities over clear sea water by a multispectral scanner installed on an aeroplane have been used. Comparisons of aerosol optical thicknesses obtained from remotely-sensed data and from ground-based atmospheric transmittancc measurements are given and discussed.     

消除halo效应和色彩失真的去雾算法

目的 雾天条件下采集的图像存在低对比度和低场景可见度的问题,传统的去雾算法易产生halo效应和色彩失真问题。为此,结合大气散射光特性提出一种基于相对总变差的图像复原方法。方法 首先从大气散射光与纹理信息无关的角度出发,利用相对总变差分离图像主结构和图像纹理信息准确估计大气耗散函数,通过引入一个自适应保护因子来避免复原图像的色彩失真问题,最后由大气散射模型计算复原图像并进行图像的亮度调整,得到一幅清晰无雾的图像。结果 通过与经典的去雾算法比较,表明该方法可以有效避免halo效应和天空颜色失真等不足,并且在图像的深度突变处也能得到很好的去雾效果。结论 实验表明该算法的场景适应能力较强,时间复杂度与图像的大小成线性关系,相比于前人的算法在计算速度上有一定的提高。     

融合MBP和EPMOD的人脸识别

摘 要：目的：单演信号分析在人脸识别中得到了日益广泛的应用,然而其中的单演方向作为一种极为重要的几何信息却未能得到充分的利用。为此,提出了一种新的增强型单演方向差分算子对单演方向进行特征提取,进而提出了融合MBP（单演二值模式）和EPMOD(增强型单演方向差分模式)的人脸识别方法。方法：首先对图像进行多种尺度的单演滤波并分别提取图片的MBP特征和EPMOD特征,然后使用BFLD(基于分块的线性fisher判别)分别对两种特征进行降维并增强两种特征的分类能力。最后,在得分级别上对两种特征进行融合并进行分类识别。结果：在ORL和CAS-PEAL人脸库上的实验表明,本文提出的EPMOD算法具有更小的时间复杂度和空间复杂度的前提下具有与MBP、LGBP相当甚至更好的识别效果。结论：本文提出了一种有效的人脸特征提取方法,实验表明本文提出的将EPMOD和MBP特征进行融合的方法能够显著地提高算法的最终识别率。     

Evaluation of a compact CAD course in laboratory experiments

With the increasing deployment of CAD, the necessity of instructing employees in the use of such systems grows; short training periods are desirable. The authors developed a compact course of 40‐hour's duration in which 32 individuals (engineering students) were instructed on a 2‐dimensional CAD system; a subsequent investigation of the achievements of the course was made with the use of laboratory experiments. In qualitative and quantitative respects the performance achieved using CAD during a drawing task was lower than that attained by the same individuals at the drawing board. A compact course of the described extent can only be the basis for self‐instruction. Interrelations between the quality of the results and the method of work exist. With regard to the performance, the variance among individuals was distinctly higher at the CAD terminal than at the drawing board. A prediction concerning the achievements of the course drawn from the performance at the drawing board, especially when based on quantitative achievements, is problematic.     

Impact analysis and change propagation in service-oriented enterprises: A systematic review

ContextThe adoption of Service-oriented Architecture (SOA) and Business Process Management (BPM) is fairly recent. The major concern is now shifting towards the maintenance and evolution of service-based business information systems. Moreover, these systems are highly dynamic and frequent changes are anticipated across multiple levels of abstraction. Impact analysis and change propagation are identified as potential research areas in this regard.ObjectiveThe aim of this study is to systematically review extant research on impact analysis and propagation in the BPM and SOA domains. Identifying, categorizing and synthesizing relevant solutions are the main study objectives.MethodThrough careful review and screening, we identified 60 studies relevant to 4 research questions. Two classification schemes served to comprehend and analyze the anatomy of existing solutions. BPM is considered at the business level for business operations and processes, while SOA is considered at the service level as deployment architecture. We focused on both horizontal and vertical impacts of changes across multiple abstraction layers.ResultsImpact analysis solutions were mainly divided into dependency analysis, traceability analysis and history mining. Dependency analysis is the most frequently adopted technique followed by traceability analysis. Further categorization of dependency analysis indicates that graph-based techniques are extensively used, followed by formal dependency modeling. While considering hierarchical coverage, inter-process and inter-service change analyses have received considerable attention from the research community, whereas bottom-up analysis has been the most neglected research area. The majority of change propagation solutions are top-down and semi-automated.ConclusionsThis study concludes with new insight suggestions for future research. Although, the evolution of service-based systems is becoming of grave concern, existing solutions in this field are less mature. Studies on hierarchical change impact are scarce. Complex relationships of services with business processes and semantic dependencies are poorly understood and require more attention from the research community.     

On fine structure of dot echoes as observed by acoustic sounder

Sometimes in the lower atmospheric boundary layer, depending upon the prevailing micro-/meso-scale meteorological condition, ‘dot’ (also known as ‘lump’) type echo structures appear generally during night-time with light wind and stable stratifications. They are associated often with disturbed atmospheric boundary layer conditions like the occurrence of thunderstorms and/or of precipitation. Digitization and scanning of individual dot/lump echo structure can indicate a cluster of points with varying echo intensity levels. In the coastal region of Calcutta they are found to be spreading vertically and the size of the cluster depends on the vertical height of occurrence. Using image processing technique fine structures of these echoes have been processed, their statisticalnature has been analysed and reported in this paper.     

Signatures of resonant and non-resonant scattering mechanisms on radar images of internal waves

The results of two polarization airborne radar imagery tests of the ocean surface obtained during the JUSREX'92 experiment are presented. It is shown that the traditional composite surface model with small-scale 'Bragg' waves superposed over larger gravity waves can not explain either the contrasts of internal wave surface manifestations in conditions of a stable atmospheric boundary layer at low grazing angles (LGA), or the apparent difference between the images obtained at different polarizations in unstable atmospheric conditions. We attribute this discrepancy to the presence of mesoscale steep waves, which produce non-resonant scattering and make different relative contributions to the total cross sections for the two polarizations. The possibility of distinguishing between surface manifestations of atmospheric and oceanic origin is also discussed.     

Global sea surface temperatures and cloud clearing for aerosol optical depth estimates

Abstract

Multichannel sea surface tempratures (MCSSTs) have been produced operationally on a global basis from AVHRR data since November 1981. Although the basic technique has been unchanged for over S years, refinements and modifications to handle special situations (e.g. volcanic and sandstorm aerosols) are under development and a cross-product (nonlinear) procedure for atmospheric corrections has been tested. The aerosol optical depth estimates have been made experimentally for about a year using AVHRR data from channel-1, and special cloud screening techniques have been developed to differentiate between clouds and aerosols.     

AVHRR Land Pathfinder II (ALP II) data set: Evaluation and inter-comparison with other data sets

A new processing chain was developed at the University of Maryland and NASA-GSFC for an improved AVHRR Land Pathfinder II (ALP II) data set. Most data sets derived from AVHRR sensor were created for specific applications and have used algorithms that have been improved or replaced in recent years. The understanding of many processes such as navigation, calibration and atmospheric water vapour absorption have increased, and can now be used to increase the quality of AVHRR data sets. The ALP II data set was compared with three data sets, the ALP I (8 km) and FASIR (1° 2 1°) data sets produced at NASA-GSFC, and LASUR (16 km) developed at CESBIO. This Letter describes evaluations of the initial 8 km AVHRR ALP II data set. This evaluation has shown a greater accuracy in atmospheric correction and temporal profiles for ALP II data set than the other AVHRR data sets.     

Zeitschrift für Arbeitswissenschaft Abstracts of papers,Vol 40 (12 NF), Part 2, 1986

Abstract

Vigilance is the ability of an observer to maintain attention for extended periods of time; however, performance tends to decline with time on watch, a pattern referred to as the vigilance decrement. Previous research has focused on factors that attenuate the decrement; however, one factor rarely studied is the effect of social facilitation. The purpose for the present investigation was to determine how different types of social presence affected the performance, workload and stress of vigilance. It was hypothesised that the presence of a supervisory figure would increase overall performance, but may occur at the cost of increased workload and stress. Results indicated that the per cent of false alarm and response times decreased in the presence of a supervisory figure. Using social facilitation in vigilance tasks may thus have positive, as well as, negative effects depending on the dependent measure of interest and the role of the observer.

Practitioner Summary: Social facilitation has rarely been examined in the context of vigilance, even though it may improve performance. Vigilance task performance was examined under social presence. The results of the present study indicated that false alarms and response times decreased in the social presence of a supervisory figure, thus improving performance.     

基于Radon-经验模式分析的纹理分类

目的 纹理分类是机器视觉和设备状态检测研究的核心技术,在工业生产领域起着重要的作用。高效的纹理分类方法不仅可以提高生产效率,还可以大幅提高产品的质量和可靠性。针对工业生产中图像纹理提取计算方法复杂等缺陷,提出一种1维化图像的纹理分类方法。方法 在图像1维化基础上,将其视为一类特殊的时域信号,引入EMD(empirical mode decomposition)特征计算方法。具体包括,通过Radon变换将2维信号1维化,评价投影信号以选取有利于分类的投影方向;对投影信号进行端点效应抑制和经验模式分解,并根据各个IMF(instrinsic mode functions)分量与原始信号构建纹理特征集;对特征集进行主成分分析,简化压缩特征集以降低特征集维数;结合支持向量机对特征集进行分类有效性评估,建立最优分类决策体系。结果 在Brodatz和KTHTIPS数据集上展开了多尺度、多方向等纹理分类实验,取得了满意的纹理分类结果。建立了基于网点纹理识别的印刷机状态检测系统,实现了工业生产应用。通过分析多幅Brodatz图像进行了特征提取速度对比,本文方法耗时5 s左右,而GLCM、Gabor滤波分别为9.5 s和24 s左右。结论 1维投影信号的IMF特征对于纹理特征有着很好的识别效果;由于进行了旋转投影选择并计算了统计特征,使得该方法对于多方向和多尺度纹理同样有效;所提出方法有着较高的计算效率。     

Remote sensing of atmospheric water content from Bhaskara SAMIR data‡

Abstract

The 19-35 GHz and 22-235 GHz passive microwave radiometers (SAMIR) on board the Indian satellite Bhaskara have provided very useful data. From these data has been demonstrated the feasibility of deriving atmospheric and ocean surface parameters such as water vapour content, liquid water content, rainfall rate and ocean surface winds. Different approaches have been tried for deriving the atmospheric water content. The statistical and empirical methods have been used by others for the analysis of the Nimbus data. A simulation technique has been attempted for the first time for 19 35 GHz and 22-235 GHz radiometer data. The results obtained from three different methods are compared with radiosonde data. A case study of a tropical depression has been undertaken to demonstrate the capability of Bhaskara SAMIR data to show the variation of total water vapour and liquid water contents.