SeaWiFS on-orbit gain and detector calibrations: effect on ocean products

The NASA Ocean Biology Processing Group's Calibration and Validation Team has analyzed the mission-long Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) on-orbit gain and detector calibration time series to verify that lunar calibrations, obtained at nonstandard gains and radiance ranges, are valid for Earth data collected at standard gains and typical ocean, cloud, and land radiances. For gain calibrations, a constant voltage injected into the postdetector electronics allows gain ratios to be computed for all four detectors in each band. The on-orbit lunar gain ratio time series show small drifts for the near infrared bands. These drifts are propagated into the ocean color data through the atmospheric correction parameter epsilon, which uses the 765/865 nm band ratio. An anomaly analysis of global mean normalized water-leaving radiances at 510 nm shows a small decrease over the mission, while an analysis of epsilon shows a corresponding increase. The drifts in the lunar time series for the 765 and 865 nm bands were corrected. An analysis of the revised water-leaving radiances at 510 nm shows the drift has been eliminated, while an analysis of epsilon shows a reduced drift. For detector calibrations, solar diffuser observations made by the individual detectors in each band allows the response of the detectors to be monitored separately. The mission-long time series of detector calibration data show that the variations in the response of the individual detectors are less than 0.5% over the mission for all bands except the 865 nm band, where the variations are less than 1%.     

On-line tuning of a single EWMA controller based on the neural technique

The exponentially weighted moving average (EWMA) controller has been proven to be an effective algorithm in the control the modern manufacturing system. The performance of the EWMA controlled process is based on choosing the correct EWMA gain. Most related research has focused on analysing the optimal EWMA gain in the static condition. The objective was to propose an approach based on the neural technique for on-line tuning of the single EWMA gain. The underlying approach indicated that the network learns very quickly when taking autocorrelation function and sample partial autocorrelation function patterns as the input features. It is shown that the sequence of the EWMA gains, generated by the proposed adaptive approach, converges close to the optimal controller value under several disturbance models, including IMA(1,1), and step and small ramp disturbances. In addition, the approach possesses a superior controlled output performance compared with the previous adaptive system.     

Flood warning by ensemble of multiple hydrological models: a case study for Typhoon Morakot

After the catastrophic disaster brought by Typhoon Morakot in 2009, the enhancement of flood warning technology cannot wait in Taiwan. In recent years, ensemble flood warning has exhibited advantages in extending lead time, quantifying uncertainty and raising confidence in issuing warnings. Unlike most ensembles aimed at integrating meteorological variations, this study generates the ensemble through the combination of multiple conceptually different hydrological models in order to avoid possible bias by applying a single model for a flood forecast. Taking Typhoon Morakot as the study case, the townships in Chiayi City/County are selected as the study areas to compare the performance of ensemble warning with that given by individual models. The results indicate that the ensemble warning shows better accuracy than individual models by giving higher overall correctness, revealing the fact that hydrological ensemble is no less important than meteorological ensemble in acquiring better flood warning performance.     

基于最小二乘法的数字图像网点补偿方法研究

目的网点大小在印刷传递过程中会不断发生变化,在数字图像中表现更为严重,为此研究控制网点扩大的方法以提高印刷品质量。方法测量喷墨打印机黑白模式下输出单色黑色靶的网点面积率,在Matlab软件平台下以最小二乘法为原理拟合实际与理想网点面积率获取网点扩大曲线,然后根据网点补偿原理推测本应输入网点值并得到网点补偿曲线,最后通过补偿曲线针对网点进行修正。结果通过测量补偿前后输出色靶,结果表明网点扩大得到了有效控制,补偿前平均网点面积扩大率为9.1%,补偿后平均网点面积扩大率为0.4%。结论观察修正后色靶,图像亮度明显提升,阶调再现性得到了提高,该方法可有效提高数字图像的输出质量。     

Three-dimensional reconstruction of resin flow using capacitance sensor data assimilation during a liquid composite molding process: A numerical study

Liquid composite molding (LCM) is a method to manufacture fiber-reinforced composites, where dry fabric reinforcement is impregnated with a resin in a molding apparatus. However, the inherent process variability changes resin flow patterns during mold filling, which in turn may cause void formation. We propose a method to reconstruct three-dimensional resin flow in LCM, without embedding sensors into the composite structure. Capacitance measured from pairs of electrodes on molding tools and the stochastic simulation of resin flow during an LCM process are integrated by a sequential data assimilation method based on the ensemble Kalman filter; then, three-dimensional resin flow and permeability distribution are estimated simultaneously. The applicability of this method is investigated by numerical experiments, characterized by different spatial distributions of permeability. We confirmed that changes in resin flow caused by spatial permeability variations could be captured and the spatial distribution of permeability could be estimated by the proposed method.     

An LED, fiber optic, gain monitoring system for a segmented scintillator array

A gain monitoring system, which uses light emitting diode flashers and a fiber optic light distribution system, has been developed for use with a segmented, liquid scintillator neutron detector array. The system is designed to track neutron detector cell gains without relying on the stability of any system components. Tests show that the system is capable of tracking the gains of individual detector cells to the design accuracy of 3%.     

High-speed GC and GC/MS with a series-coupled column ensemble using stop-flow operation

A pneumatically actuated valve is used to connect the junction point of a series-coupled column ensemble to a ballast chamber containing carrier gas at the ensemble inlet pressure in order to periodically stop the carrier gas flow in the first column. When the valve is opened, mixture components, which have migrated across the column junction, are accelerated toward a time-of-flight mass spectrometer that is used as an ensemble detector. Mixture components, which are still in the first column, are frozen in position. This allows for the insertion of time windows into the ensemble chromatogram that can aid in the separation of some overlapping component peaks. The capillary column ensemble (0.18-mm i.d. x 0.18-microm film thickness) consists of a 7.0-m length of polar, (trifluoropropyl)methyl polysiloxane column followed by a 7.0-m length of nonpolar dimethyl polysiloxane column. A flame ionization detector located at the column junction point is used to monitor a portion of the effluent from the first column in order to determine the valve timing sequence needed to enhance the separation of component pairs that are separated by the first column but coelute from the column ensemble. When one of the components of a targeted pair has crossed the junction but the other component is still in the first column, the valve is opened, typically for 1-5 s. The stop-flow system is used to enhance the separation of a mixture containing some common essential oil components and a mixture containing some common pesticides.     

Pedestrians, vehicles, and cell phones

With cellular phones and portable music players becoming a staple in everyday life, questions have arisen regarding the attentional deficits that might occur when such devices are used while performing other tasks. Here, we used a street-crossing task in an immersive virtual environment to test how this sort of divided attention affects pedestrian behavior when crossing a busy street. Thirty-six participants navigated through a series of unsigned intersections by walking on a manual treadmill in a virtual environment. While crossing, participants were undistracted, engaged in a hands free cell phone conversation, or listening to music on an iPod. Pedestrians were less likely to successfully cross the road when conversing on a cell phone than when listening to music, even though they took more time to initiate their crossing when conversing on a cell phone (∼1.5 s). This success rate difference was driven largely by failures to cross the road in the allotted trial time period (30 s), suggesting that when conversing on a cell phone pedestrians are less likely to recognize and act on crossing opportunities.     

A method to compensate periodic errors by gain tuning ininstrumentation

The method described uses multiprobes without individual probes accuracy calibrations. By simple gain (or sensitivity) tuning, perfect compensation of any arbitrary frequency component of an error is achieved. Online calculations or estimations of the periodic error are not required, and significant improvements are achieved just by initial tuning of the gains of separate probes. In Sections II and III, we first derive a mathematical model of the periodic error and then propose a new method to compensate it. In. Section IV, we derive the minimum number of probes needed to compensate a given number of frequency components of the periodic error, and present two algorithms to calculate the gains for separate probes. In Section V, we show two simulated and one experimental example of periodic error compensation. One of the simulated examples is applied to a rotary type of a sensor and the other to a linear type of a sensor. Minimum number of probes needed to compensate multiple frequency components is also derived. The method is successfully demonstrated on two simulated and one experimental example, where one and two frequency components of a periodic error are perfectly compensated. The method is applicable both to rotary and to linear types of sensors     

A Fast-Acting Feedback Loop for Pulse Amplitude Ratio Measurement

Design and operating details of a voltage ratio measuring circuit are presented. The circuit employs a wide bandwidth function multiplier as a variable gain amplifier. The denominator voltage activates a feedback loop causing multiplier gain adjustment. Adjustment proceeds until the multiplier output is equal to a Zener reference voltage. The multiplier gain is then equal to the ratio of Zener reference voltage to denominator voltage. Multiplier gain is stored by an integrator serving as a memory. The numerator voltage does not activate the feedback loop, but is simply amplified by the multiplier. The resulting output voltage is the ratio of the input voltages referred to a Zener reference. Null-balance time of 5 ?S allows ratio measurement of 16-kc pulse pairs.     

Integrated product design,shelf-space allocation and transportation decisions in green supply chains

In this paper, we examine a supply chain consisting of a manufacturer and retailer where the manufacturer undertakes greening efforts in terms of pack-size reduction and transportation cost reduction. The retailer decides on shelf-space allocation for the product. Both the players benefit from the greening efforts of the manufacturer. In such a setting, we examine strategic decisions of the players and compare and contrast the performance of the decentralised supply chain with the centralised supply chain. We also examine the effect of collaborative mechanisms by modelling two contracts in which the retailer offers a transportation cost reduction effort based contract and a two-part tariff contract. We find that the decentralised supply chain leads to lower greening efforts and shelf-space allocation decisions. We also find that the contracts improve pack-size reduction effort, transportation cost reduction effort and shelf-space allocation, while also improving the profitability of individual players. The findings demonstrate a scope for supply chain collaboration between manufacturer–retailer pairs in this setting. The paper uniquely combines three critical elements in supply chains, namely, product design, transportation and retailing decisions, and aims to provide insights into the decision making of players considering environmental waste and pollution. The paper also reflects consumer behavior and trade-offs that the supply chain players face.     

外推法天线增益测量的核心算法及实验研究

基于外推法测量原理研究了外推法天线增益测量核心算法,重点在于天线互耦的滤波抑制、功率级数展开式的拟合和任意距离下的天线增益求解.此外,还基于以上核心算法设计了一款外推法天线增益测量界面,为外推法天线增益的精密测量提供便利.最后,开展了 W波段标准天线的增益校准实验,增益测量结果与NPL的测量偏差小于0.04 dB,实现...     

Stop-flow programmable selectivity with a dual-column ensemble of microfabricated etched silicon columns and air as carrier gas

A series-coupled ensemble of microfabricated GC columns made by dry reactive ion etching of silicon substrates is evaluated for use with pneumatic selectivity enhancement techniques for targeted pairs of volatile organic compounds. Each column is 3.0 m long with a 150 miceom wide by 240 microm deep cross section. Dynamic coating was used to prepare a nonpolar column with a dimethyl polysiloxane stationary phase and a moderately polar column with a trifluoropropylmethyl polysiloxane stationary phase. Each column generates 5000-6000 theoretical plates. The columns are operated in series with the nonpolar column connected to a split inlet, the polar column connected to a flame ionization detector, and a valve connected between the column junction point and the inlet to the first column. When the valve is closed, the effluent from the first column passes directly into the second column. When the valve is open, both ends of the first column are at the inlet pressure, and flow stops in this column while increased flow is obtained in the second column. For analyte pairs that are separated by the first column but coelute from the column ensemble, the valve is opened for a few seconds after the first component of the pair has passed into the second column but the second component is still in the first column. The result is enhanced separation of the pair in the ensemble chromatogram. Relatively thick cross-linked stationary-phase films are used to increase retention for volatile compounds. The combination of air carrier gas and stationary-phase film thickness in the range 1-2 microm requires the use of relatively low average carrier gas velocities (typically less than 10 cm/s) for adequate resolving power of the column ensemble. Selectivity enhancement under isothermal conditions for a 14-component mixture of volatile organic compounds is demonstrated where neither of the columns alone nor the column ensemble without selectivity enhancement could obtain a complete separation.     

A discrete model of neural ensembles

A discrete model of an ensemble of identical stochastic integrate-and-fire neurons is used to study the patterns of activity in populations of neurons that exchange excitatory messages. In a regime with small interactions among the units, the effect of the message exchange is to reduce the dispersion of the firing period of the individual neurons. In a strong interaction regime, a number of activity clusters emerge in the ensemble. Neurons in each cluster fire periodically and in synchrony with each other. The number of these self-sustained firing states characterized by distinct firing patterns towards which the network can evolve is very large. Because of their stability with respect to intrinsic fluctuations in the dynamics of the stochastic neurons, these states could, in principle, be used to encode and process large amounts of information.     

基于ICC阶调调整的陶瓷喷墨印刷颜色校正

目的 为了解决不同批次陶瓷制品的颜色一致性问题,提出一种基于ICC编辑的陶瓷喷墨制品颜色校正方法.方法 根据二分法原理,通过实验测量,找出网点阶调修正的颜色校正模型最佳校正参数a值,计算并绘制各单色通道色彩调整曲线Si.结果 应用经过Si值网点补偿校正后的ICC特性曲线,印刷并输出网点阶调测试色卡,测量得出各通道网点百分比的阶调值与基准值的平均差值减小到0.4％.结论 提出的基于ICC编辑的陶瓷喷墨印刷制品颜色校正方法有效解决了同一印前文件不同批次陶瓷制品颜色不一致的问题.     

Low radar cross-section and high performances of microstrip antenna using fractal uniplanar compact electromagnetic bandgap ground

By using surrounding periodic second-uniplanar compact electromagnetic bandgap (UC-EBG) ground plane, a microstrip patch antenna working at X-band with low radar cross-section (RCS) and high performance was designed. The main parameters such as return loss, impedance bandwidth, RCS, radiation patterns and gains are presented and discussed. Comparison of the patch antenna with the surrounding periodic second-UC-EBG ground suggests that the second-UC-EBG has much lower RCS than the standard patch antenna at a band range 2-18 GHz. In addition, gain, bandwidth and radiation patterns of the former are all improved when compared with those of the latter.     

数字影像获取中的色彩控制

色彩控制是数字影像获取中与曝光控制、清晰度控制并列的三大控制技术之一，它必须通过色彩位数选择控制色彩表现细节，借助于白平衡调整控制色别的准确再现，依托色彩空间的不同控制颜色表现的种类与范围，利用不同的色彩模式使色彩适应不同人的喜好与不同的应用。     

Hihg-speed GC/MS of gasoline-range hydrocarbon compounds using a pressure-tunable column ensemble and time-of-flight detection

A pressure-tunable series-coupled ensemble of two capillary GC columns is combined with a time-of-flight MS detector for the high-speed characterization of mixtures containing hydrocarbon compounds. The column ensemble consists of a nonpolar 5% phenyl poly(dimethylsiloxane) column and a very polar poly(ethylene glycol) column. The TOFMS instrument uses time-array detection to obtain up to 500 complete electron mass spectra per second. Instrument software allows for automated peak finding and the spectral deconvolution of severely overlapping unknown chromatographic peaks, if their fragmentation patterns are significantly different and if at least two spectra can be recorded between the peak apexes. By adjusting the carrier-gas pressure at the column-junction point, the separations between adjacent peak pairs can be adjusted to enhance the capabilities of the TOFMS detector. The sensitivity of peak-pair separation to changes in junction-point pressure is studied for combinations of alkanes, olefins, and aromatic compounds. When complete separation is required, the use of pressure-tunable column ensembles cannot always provide sufficient control of peak-pair separation for structurally similar compounds. However, complete chromatographic separation typically is not required with the TOFMS detection, and a pressure-tunable column ensemble is very useful for the high-speed characterization of hydrocarbon mixtures.     

Harmony search algorithm: application to the redundancy optimization problem

The redundancy optimization problem is a well known NP-hard problem which involves the selection of elements and redundancy levels to maximize system performance, given different system-level constraints. This article presents an efficient algorithm based on the harmony search algorithm (HSA) to solve this optimization problem. The HSA is a new nature-inspired algorithm which mimics the improvization process of music players. Two kinds of problems are considered in testing the proposed algorithm, with the first limited to the binary series–parallel system, where the problem consists of a selection of elements and redundancy levels used to maximize the system reliability given various system-level constraints; the second problem for its part concerns the multi-state series–parallel systems with performance levels ranging from perfect operation to complete failure, and in which identical redundant elements are included in order to achieve a desirable level of availability. Numerical results for test problems from previous research are reported and compared. The results of HSA showed that this algorithm could provide very good solutions when compared to those obtained through other approaches.     

基于动态集成的遥感图像分类

鉴于多分类器集成能够获得比单个分类器更好的性能,但是对于支持向量机(support vector ma-chine,SVM),一般的集成方法很难达到效果.特提出了基于局部精度(local accuracy,LA)的动态集成算法.首先,通过多种方法产生个体分类器;其次,利用验证数据集来定义LA,LA用来衡量各个体分类器的权重以及判断是否挑选该个体分类器的标准;最后,在某研究区的遥感图像数据集上进行实验.实验结果表明,动态集成的效果要优于静态集成,特别是异类动态集成效果最好.静态集成只考虑了分类器在训练样本中的表现而没有考虑测试样本的特征,对于动态集成,可以根据测试样本在验证集上的表现来选择个体分类器,因此它展现出更好的性能.