Albedo of vegetated surfaces: its variability with differing irradiances

The albedo of four vegetated surfaces was investigated to derive its variability with differing distributions of the irradiance. The results are based on measured values of the spectral biconical reflectance factor, which are combined with calculated spectral irradiances for low and high atmospheric turbidity. The solar zenith angle is varied from 0° to 80°. The derived spectral albedos are then integrated with respect to wavelength in order to achieve the albedo. It is found that the variability of the albedo with respect to the atmospheric turbidity is less than 0.01 in nearly all cases. The variability of the albedo with respect to the solar elevation angle, however, is larger than 0.02 in many cases. For solar elevation angles from 20° to 60°, the variability of the albedo of the four surfaces can be represented by a mean curve which fits the individual variabilities with an accuracy of 0.015.     

Observed relation between thermal emission and reflected spectral radiance of a complex vegetated landscape

An investigation is conducted, for a complex vegetated land area, into the statistical relationship between remotely sensed thermal emissions and reflected spectral radiance. The Kauth—Thomas Tasseled Cap transformation is employed to infer the albedo and amount of green vegetation present from Landsat multispectral scanner (MSS) observations. Reflective data and thermal infrared data were acquired from the Heat Capacity Mapping Mission (HCMM) satellite along with reflective data from the Landsat 3 MSS for a site near Hartford, CT on a single date. Results are presented which indicate that thermal emissions had the greatest association with the amount of vegetation as indicated by a multispectral index, while albedo did not exhibit any substantial relationship with these emissions. These findings are explained in terms of the enhanced latent heat flux to the atmosphere associated with actively transpiring vegetation.     

A program to determine the radiation spectra due to a single atomic-subshell ionisation by a particle or due to deexcitation or decay of radionuclides

The computer program IMRDEC has been developed to determine the radiation spectra due to a single atomic-subshell ionisation of a stable atom by a particle, or due to the atomic deexcitation or decay of nuclides. The data needed to describe the deexcitation or decay scheme of the mother atoms are obtained from the Evaluated Nuclear Structure Data File (ENSDF) maintained at Brookhaven National Laboratory; this results in the simplest possible input specification. The atomic data as well as the atomic relaxation probabilities are taken from the Evaluated Atomic Data Library (EADL) from Lawrence Livermore National Laboratory. The program IMRDEC calculates the radiation spectra (inclusive the atomic relaxation cascades) optionally, using the deterministic or the Monte Carlo method. The deterministic method results in a much shorter calculation time per nuclide. Due to the many assumptions that worldwide still have to be made in determining the atomic relaxation probabilities as well as in calculating the atomic relaxation, the deterministic method seems to be a small source of inaccuracy.     

Response variability of laminate composite plates due to spatially random material parameter

Young’s modulus is at the center of attention in the stochastic finite element analysis since the parameter plays an important role in determining structural behavior. However, the other material parameter of Poisson’s ratio is another independent material parameter that governs the behavior of structural systems. Accordingly, the independent estimation of the influence of this parameter on the uncertain response of a system is of importance from the perspective of stochastic analysis. To this end, we propose a formulation to determine the response variability in laminated composite plates due to the spatial randomness of Poisson’s ratio. To filter out the independent contribution of random Poisson’s ratio, a decomposition of the constitutive matrix into several sub-matrices by using the Taylor’s expansion is needed, which makes the random Poisson’s ratio simple enough to be included in the formulation. To validate the adequacy of the proposed formulation, several examples are chosen and the results are compared with those given by Monte Carlo analysis. By means of the formulation suggested here, it is expected that an extension of the formulation to include the effect of correlations between random Poisson’s ratio and other structural and/or geometrical parameters will be achieved with ease, resulting in a more practical estimation of the response variability of laminated composite plates.     

The changes of lumbar muscle flexion-relaxation phenomenon due to antero-posteriorly slanted ground surfaces

Uneven ground surface is a common occupational injury risk factor in industries such as agriculture, fishing, transportation and construction. Studies have shown that antero-posteriorly slanted ground surfaces could reduce spinal stability and increase the risk of falling. In this study, the influence of antero-posteriorly slanted ground surfaces on lumbar flexion-relaxation responses was investigated. Fourteen healthy participants performed sagittally symmetric and asymmetric trunk bending motions on one flat and two antero-posteriorly slanted surfaces (?15° (uphill facing) and 15° (downhill facing)), while lumbar muscle electromyography and trunk kinematics were recorded. Results showed that standing on a downhill facing slanted surface delays the onset of lumbar muscle flexion-relaxation phenomenon (FRP), while standing on an uphill facing ground causes lumbar muscle FRP to occur earlier. In addition, compared to symmetric bending, when performing asymmetric bending, FRP occurred earlier on the contralateral side of lumbar muscles and significantly smaller maximum lumbar flexion and trunk inclination angles were observed.

Practitioner Summary: Uneven ground surface is a common risk factor among a number of industries. In this study, we investigated the influence of antero-posteriorly slanted ground surface on trunk biomechanics during trunk bending. Results showed the slanted surface alters the lumbar tissue load-sharing mechanism in both sagittally symmetric and asymmetric bending.     

Flow due to a convectively heated cylinder with nonlinear thermal radiation

Neural Computing and Applications - This communication presents non-Newtonian fluid flow over a stretching cylinder. Rheological relations of second-grade fluid are employed in the modeling. Heat...     

Multi-time-scale heat transfer modeling of turbid tissues exposed to short-pulsed irradiations

A combined hyperbolic radiation and conduction heat transfer model is developed to simulate multi-time-scale heat transfer in turbid tissues exposed to short-pulsed irradiations. An initial temperature response of a tissue to an ultrashort pulse irradiation is analyzed by the volume-average method in combination with the transient discrete ordinates method for modeling the ultrafast radiation heat transfer. This response is found to reach pseudo steady state within 1 ns for the considered tissues. The single pulse result is then utilized to obtain the temperature response to pulse train irradiation at the microsecond/millisecond time scales. After that, the temperature field is predicted by the hyperbolic heat conduction model which is solved by the MacCormack's scheme with error terms correction. Finally, the hyperbolic conduction is compared with the traditional parabolic heat diffusion model. It is found that the maximum local temperatures are larger in the hyperbolic prediction than the parabolic prediction. In the modeled dermis tissue, a 7% non-dimensional temperature increase is found. After about 10 thermal relaxation times, thermal waves fade away and the predictions between the hyperbolic and parabolic models are consistent.     

Canopy blockage and scattering effects on apparent soil spectral reflectance and its consequence in spectral mixture analysis of vegetated surfaces

Remote sensing technique has become the most efficient and common approach to estimate surface vegetation cover. Among various remote sensing algorithms, spectral mixture analysis (SMA) is the most common approach to obtain sub‐pixel surface coverage. In the SMA, spectral endmembers (the number of endmembers may vary), with invariant spectral reflectance across the whole image, are needed to conduct the mixture procedure. Although the nonlinear effect in quantifying vegetation spectral reflectance was noticed and sometimes addressed in the SMA analysis, the nonlinear effect in soil spectral reflectance is seldom discussed in the literature. In this paper, we investigate the effects of vegetation canopy on the inter‐canopy soil spectral reflectance via mathematical modelling and field measurements. We identify two mechanisms that lead to the difference between remotely sensed apparent soil spectral reflectance and actual soil spectral reflectance. One is a canopy blockage effect, leading to a reduced apparent soil spectral reflectance. The other is a canopy scattering effect, leading to an increased apparent soil spectral reflectance. Without correction, the first (second) mechanism causes an overestimated (underestimated) areal coverage of the low‐spectral‐reflectance endmember. The overall effect of canopy to soil, however, tends to overestimate fractional vegetation cover due to the relative significance of the canopy blockage effect, even though the two mechanisms vary with spectral wavelengths and spectral difference between different vegetation and soil. For the SMA of vegetated surface using multiple‐spectral remote sensing imagery (e.g., LandSat), it is recommended that infrared bands of low vegetation spectral reflectance (e.g. band 7) be first considered; if both visible and infrared bands are used, combination of bands 3, 4, and 5 is appropriate, while use of all six bands could overestimate fraction vegetation cover.     

Recognition of shiny dielectric objects by analysing the polarization of reflected light

The degree of polarization of light reflected from a transparent or translucent object depends only upon the angle of incidence, refractive index and absorption coefficient of the material. It is therefore possible to determine the orientation of the surface normal from the direction of the plane of polarization. The feasibility of this is demonstrated both theoretically and practically by calculating and measuring the reflectance map of a sphere when viewed through a plane polarizing filter. Ambiguities in the mapping from radiance to orientation are removed by orienting the filter at three angles. The orientation of our objects is determined to within an uncertainty of less than seven degrees.     

TFT-LCD面板反射的能量对光斑图像的影响

针对基于激光三角测距原理设计的显微镜自动对焦系统中,光斑在TFT-LCD面板上表面或者下表面聚焦时的鬼影以及打在金属丝上的光斑畸变问题,提出在焦平面附近调节相机快门和增益以消除鬼影,并根据相机快门时间动态变换光斑中心的求解方法.分析了光斑鬼影产生的原因和消除方法以及当光斑图像不同程度打在金属丝上时,导致光斑图像局部明显增强的特性,给出了求解光斑中心的方法.实验结果表明,光斑中心位置和离焦量线性拟合R的平方值为0.991,减少了激光三角测距法的非线性误差,实现了非接触快速对焦.     

Measuring trunk motions in industry: variability due to task factors, individual differences, and the amount of data collected

The focus of this study was to determine the amount of data needed to ensure sufficient accuracy in estimating mean trunk motions of employees performing industrial manual materials handling tasks. Over 450 tasks were selected, in which the load weight and the vertical start and destination heights of the activity remained constant throughout the task. Data were collected as employees did their work at the job site, using the Lumbar Motion Monitor. Variance components were estimated in a hierarchical design and used to compute standard errors of mean trunk kinematic measures. These analyses found task-to-task variation to be much larger than the variability due to either multiple employees performing the same task or to repetitive movements within a task. Also, it was found that no significant reduction in the standard errors occurred when data were gathered for more than three employees and three repetitions of each task by an employee. This study indicates that the vast majority of variability in mean trunk motions is accounted for by the design of work tasks, and variations due to repeated cycles of a task or to employees are rather minor. It is also important as a basis for future work on modelling low-back disorder risk based on a job's trunk kinematic measures.     

Measuring trunk motions in industry: variability due to task factors,individual differences,and the amount of data collected

The focus of this study was to determine the amount of data needed to ensure sufficient accuracy in estimating mean trunk motions of employees performing industrial manual materials handling tasks. Over 450 tasks were selected, in which the load weight and the vertical start and destination heights of the activity remained constant throughout the task. Data were collected as employees did their work at the job site, using the Lumbar Motion Monitor. Variance components were estimated in a hierarchical design and used to compute standard errors of mean trunk kinematic measures. These analyses found task-to-task variation to be much larger than the variability due to either multiple employees performing the same task or to repetitive movements within a task. Also, it was found that no significant reduction in the standard errors occurred when data were gathered for more than three employees and three repetitions of each task by an employee. This study indicates that the vast majority of variability in mean trunk motions is accounted for by the design of work tasks, and variations due to repeated cycles of a task or to employees are rather minor. It is also important as a basis for future work on modelling low-back disorder risk based on a job's trunk kinematic measures.     

改进滑动平均滤波在PSO辨识中的应用

在实际系统信号中不可避免的会存在噪声和瞬时扰动,噪声过大会严重影响粒子群优化算法(pso)的辨识结果.针对强噪声环境下利用PSO算法进行参数辨识精度差甚至不能收敛的问题,提出了一种改进的滑动平均滤波算法,通过动态修正滑动平均后的数据相位,来实现无滞后的滑动平均滤波效果.仿真实验表明,对这种改进滑动平均滤波算法应用于PS...     

The relationship between the biomass of Cameroonian tropical forests and radiation reflected in middle infrared wavelengths (3.0-5.0 mu m)

The use of middle infrared (MIR) radiation (3.0-5.0 mu m) at the regional scale may be unreliable for biophysical estimation, should be corrected for thermal emission and MIR reflectance used in its place. This study considered the potential use of MIR reflectance for studying tropical forests, with the relationship between MIR reflectance and estimated total biomass of the tropical forests of Cameroon derived. Comparisons were drawn with relationships between estimated total biomass and visible reflectance, near infrared reflectance, MIR radiation and surface temperature. Relationships between two vegetation indices, the NDVI and VI3, and estimated total biomass were also explored. It was found that correcting MIR radiation for thermal emission increased the strength of the relationship between radiation acquired in MIR wavelengths and estimated total biomass. The use of MIR reflectance, either alone or within the vegetation index VI3, provided the strongest relationship with estimated total biomass. This suggests that MIR reflectance may be more sensitive to changes in forest properties than the reflectance in visible and NIR wavelengths. It is recommended that MIR reflectance should be adopted more widely for the remote sensing of tropical forests.     

MHD flow and heat transfer of a generalized Burgers’ fluid due to an exponential accelerating plate with the effect of radiation

This paper presents a research for the MHD flow and heat transfer of an incompressible generalized Burgers’ fluid due to an exponential accelerating plate with the effect of radiation. The fractional calculus approach is used to establish the constitutive relationship of the viscoelastic fluid. Exact analytic solutions are obtained for the velocity and temperature fields in integral and series form in terms of the G function by means of Fourier sine transform and Laplace transform. Moreover, the figures are plotted to show the effects of different parameters on the velocity and temperature fields.     

Communicating the variability of a software-product family to customers

Variability is a central concept in software product family development. Variability empowers constructive reuse and facilitates the derivation of different, customer specific products from the product family. If many customer specific requirements can be realised by exploiting the product family variability, the reuse achieved is obviously high. If not, the reuse is low. It is thus important that the variability of the product family is adequately considered when eliciting requirements from the customer. In this paper we sketch the challenges for requirements engineering for product family applications. More precisely we elaborate on the need to communicate the variability of the product family to the customer. We differentiate between variability aspects which are essential for the customer and aspects which are more related to the technical realisation and need thus not be communicated to the customer. Motivated by the successful usage of use cases in single product development we propose use cases as communication medium for the product family variability. We discuss and illustrate which customer relevant variability aspects can be represented with use cases, and for which aspects use cases are not suitable. Moreover we propose extensions to use case diagrams to support an intuitive representation of customer relevant variability aspects. Received: 14 October 2002 / Accepted: 8 January 2003 Published online: 27 February 2003 This work was partially funded by the CAFé project “From Concept to Application in System Family Engineering”; Eureka Σ! 2023 Programme, ITEA Project ip00004 (BMBF, F?rderkennzeichen 01 IS 002 C) and the state Nord-Rhein-Westfalia. This paper is a significant extension of the paper “Modellierung der Variabilit?t einer Produktfamilie”, [15].     

On the fitting of surfaces to data with covariances

We consider the problem of estimating parameters of a model described by an equation of special form. Specific models arise in the analysis of a wide class of computer vision problems, including conic fitting and estimation of the fundamental matrix. We assume that noisy data are accompanied by (known) covariance matrices characterizing the uncertainty of the measurements. A cost function is first obtained by considering a maximum-likelihood formulation and applying certain necessary approximations that render the problem tractable. A Newton-like iterative scheme is then generated for determining a minimizer of the cost function. Unlike alternative approaches such as Sampson's method or the renormalization technique, the new scheme has as its theoretical limit the minimizer of the cost function. Furthermore, the scheme is simply expressed, efficient, and unsurpassed as a general technique in our testing. An important feature of the method is that it can serve as a basis for conducting theoretical comparison of various estimation approaches.     

The estimation of the surface moisture of a vegetated soil using aerial infrared photography

The bidirectional reflectance of near infrared wavelengths of electromagnetic radiation from a vegetation canopy is primarily determined by the relative area and reflectance of the canopy and canopy dependent components: leaves, non-green vegetation, soil and shadow. It has been shown that when the percentage cover of leaves and non-green vegetation are both known and constant and the effect of shadow is minimal, then the near infrared bidirectional reflectance from the-canopy is negatively related to surface soil moisture.

This study was based on the above observation to estimate surface soil moisture of a vegetated soil from remotely sensed measurements of near infrared bidirectional reflectance.

The near infrared bidirectional reflectance, surface soil moisture and vegetation cover were measured at 10 heathland sites on 18 dates. The surface soil moisture was significantly related (at better than the 1 per cent level) to the Y axis intercept, when near infrared bidirectional reflectance (Y) was regressed against the percentage cover of green vegetation (X). This relationship between soil moisture and canopy reflectance was then used to enable the surface soil moisture of vegetated heathland soil to be estimated by means of five flights of black and white infrared aerial photography. It proved possible to estimate the surface soil moisture of the vegetated soil with an accuracy of ±18·4 percent at the 95 percent confidence limits. Possible improvements to the technique are discussed.