Internal representations of temporal statistics and feedback calibrate motor-sensory interval timing.

Humans have been shown to adapt to the temporal statistics of timing tasks so as to optimize the accuracy of their responses, in agreement with the predictions of Bayesian integration. This suggests that they build an internal representation of both the experimentally imposed distribution of time intervals (the prior) and of the error (the loss function). The responses of a Bayesian ideal observer depend crucially on these internal representations, which have only been previously studied for simple distributions. To study the nature of these representations we asked subjects to reproduce time intervals drawn from underlying temporal distributions of varying complexity, from uniform to highly skewed or bimodal while also varying the error mapping that determined the performance feedback. Interval reproduction times were affected by both the distribution and feedback, in good agreement with a performance-optimizing Bayesian observer and actor model. Bayesian model comparison highlighted that subjects were integrating the provided feedback and represented the experimental distribution with a smoothed approximation. A nonparametric reconstruction of the subjective priors from the data shows that they are generally in agreement with the true distributions up to third-order moments, but with systematically heavier tails. In particular, higher-order statistical features (kurtosis, multimodality) seem much harder to acquire. Our findings suggest that humans have only minor constraints on learning lower-order statistical properties of unimodal (including peaked and skewed) distributions of time intervals under the guidance of corrective feedback, and that their behavior is well explained by Bayesian decision theory.

Design and simulation of SMES system using YBCO tapes for direct drive wave energy converters

The ocean represents a huge energy reservoir since waves can be exploited to generate clean and renewable electricity; however, a hybrid energy storage system is needed to smooth the fluctuation. In this paper a hybrid energy storage system using a superconducting magnetic energy system (SMES) and Li-ion battery is proposed. The SMES is designed using Yttrium Barium Copper Oxide (YBCO) tapes, which store 60 kJ electrical energy. The magnet component of the SMES is designed using global optimization algorithm. Mechanical stress, coupled with electromagnetic field, is calculated using COMSOL and Matlab. A cooling system is presented and a suitable refrigerator is chosen to maintain a cold working temperature taking into account four heat sources. Then a microgrid system of direct drive linear wave energy converters is designed. The interface circuit connecting the generator and storage system is given. The result reveals that the fluctuated power from direct drive linear wave energy converters is smoothed by the hybrid energy storage system. The maximum power of the wave energy converter is 10 kW. © 2012 IEEE.

Shaping pulse transitions by active voltage control for reduced EMI generation

High-performance power switching devices (IGBT/MOSFET) realise high-performance power converters. Unfortunately, with a high switching speed of the IGBT or MOSFET freewheel diode chopper cell, the circuit has intrinsic sources of high-level EMI. Therefore, costly EMI filters or shielding are normally demanded on the load and supply side. Although an S-shaped voltage transient with a high order of derivation eliminates the discontinuity and could suppress HF spectrum of EMI emissions, a practical control scheme is still under development. In this paper, Active Voltage Control (AVC) is applied to successfully define IGBT switching dynamics with a smoothed Gaussian waveform so a reduced EMI can be achieved without extra EMI suppression devices. © 2013 IEEE.

Comparative studies on photosynthesis and phosphate metabolism of Cylindrospermopsis raciborskii with Microcystis aeruginosa and Aphanizomenon flos-aquae

The physiological differences for three bloom-forming cyanobacteria (Cylindrospermopsis raciborskii, Microcystis aeruginosa, and Aphanizomenon flos-aquae) were investigated. In comparison with M. aeruginosa and A. flos-aquae, C. raciborskii exhibited a significantly higher concentration of carotenoids, higher values in maximum photosynthesis rate (P-m), apparent photosynthetic efficieny (a), and maximum electron transport rate (ETRmax) during the growth period. In addition, higher extracellular alkaline phosphatase activities and lower light compensation point (I-c) were also detected in C raciborskii (p < 0.05, ANOVA). Therefore, it is suggested that the higher photosynthetic activities, more effective uptake and utilization to phosphate, and low light requirements might play important roles in the occurrence and invasive behavior of C. raciborskii. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved.

Using epilithic diatom communities to assess ecological condition of Xiangxi River system

Assessment method for ecological condition of Xiangxi River system was studied by using 13 candidate metrics of epilithic diatom which can reflect conditions in pH, salinity, nitrogen uptake metabolism, oxygen requirements, saprobity, trophic state, morphological character and pollution tolerant capability etc. By one-way ANOVA, the metrics of relative abundance of acidobiontic algae (ACID), freshwater algae (FRESH), high oxygen requirement (HIGH-O), eutraphentic state (EUTRA) and mobile taxa ( MOBILE) were suitable for distinguishing sites in different conditions. Then, the river diatom index (RDI) composed of these five metrics was used to evaluate ecological condition of the river. The results showed that the healthiest sites were in the Guanmenshan Natural Reserve ( with the mean RDI of 79.73). The sites located in tributary of Jiuchong River also owned excellent state (mean RDI of 78.25). Mean RDI of another tributary - Gufu River and the main river were 70.85 and 68.45 respectively, and the unhealthiest tributary was Gaolan River (with mean RDI of 65.64). The mean RDI for all the 51 sites was 71.40. The competence of RDI was discussed with comparison of evaluation results of DAIpo and TDI, it can be concluded that multimetrics is more competent in assessment task.

Origin of the double- and multi-pulse structure of echolocation signals in Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientialis)

The signals of dolphins and porpoises often exhibit a multi-pulse structure. Here, echolocation signal recordings were made from four geometrically distinct positions of seven Yangtze finless porpoises temporarily housed in a relatively small, enclosed area. Some clicks demonstrated double-pulse, and others multi-pulse, structure. The interpulse intervals between the first and second pulse of the double- and multi-pulse clicks were significantly different among data from the four different positions (p < 0.01, one-way ANOVA). These results indicate that the interpulse interval and structure of the double- and multi-pulse echolocation signals depend on the hydrophone geometry of the animal, and that the double- and multi-pulse structure of echolocation signals in Yangtze finless porpoise is not caused by the phonating porpoise itself, but by the multipath propagation of the signal. Time delays in the 180 degrees phase-shifted surface reflection pulse and the nonphase-shifted bottom reflection pulse of the multi-pulse structures, relative to the direct signal, can be used to calculate the distance to a phonating animal. (c) 2005 Acoustical Society of America.

Abnormal effect of growth interruption on GaSb quantum dots formation grown by molecular beam epitaxy

The growth interruption (GI) effect on GaSb quantum dot formation grown on GaAs by molecular beam epitaxy was investigated. The structure characterization was performed by reflection high-energy electron diffraction (RHEED), along with photoluminescence measurements. It is found that the GI can significantly change the surface morphology of GaSb QDs. During the GI, the QDs structures can be smoothed out and turned into a 2D-like structure. The time duration of the GI required for the 3D/2D transition depends on the growth time of the GaSb layer. It increases with the increase of the growth time. Our results are explained by a combined effect of the stress relaxation process and surface exchange reactions during the GI. (C) 2002 Elsevier Science B.V. All rights reserved.

基于核方法的敏感信息过滤的研究

在深入分析敏感信息过滤任务的特点和难点的基础上,针对现有一般的信息过滤方法的不足,提出了一种利用敏感词的组合信息来改进过滤效果的思想.进而,研究了在核方法的框架下特征共现行为建模的原则并提出了复合ANOVA核来刻画特征组合行为.通过真实信息过滤环境中的测试评估,显示了此敏感信息过滤方法的有效性.

云南大山包黑颈鹤(Grus nigricollis)越冬行为和保护研究

从2006 年10 月24 日至2007 年4 月9 日，采用固定样线法和瞬时扫描法， 对在大山包国家级自然保护区（N27°18′38″～27°29′15″，E103°14′55″～103°23′49″） 内越冬的黑颈鹤种群进行了越冬行为、日间活动节律和越冬栖息地利用的详细调 查，同时对黑颈鹤的春季迁徙行为和冬季黑颈鹤的死亡现象进行了观察和分析。 这些研究有助于我们了解黑颈鹤是采取何种行为模式和栖息地利用模式来适应高 海拔、低温度的环境，同时对如何有效地保护越冬黑颈鹤和合理规划保护区功能 区域有重要的指导作用。 将黑颈鹤的越冬行为分为：取食（Feeding）、搜寻（Searching）、警戒（Vigilance）、 争斗（Fight）、行走（Walk）、飞行（Flight）、休整（Maintenance）和其它（Others） 八种，越冬期间最主要的行为是取食（53.05±4.93）％，其它行为依次为：搜寻 （10.38±1.34）％、警戒（18.75±2.65）%、休整（10.32±4.93）％、行走（4.90±1.59） ％、飞行（1.70±0.38）％、争斗（0.36±0.25）％、其它（0.55±0.41）％。单因素 方差分析（One-Way ANOVA）分析表明越冬期间黑颈鹤日间各时间段（1h）和各 月份间行为差异极显著（P<0.05），并呈现出规律的变化。黑颈鹤的取食、警戒、 搜寻行为具明显的早（10:00-11:00）、晚（17:00-18:00）两个活动高峰，中午 13:00~14:00 最低；而休整行为正好相反，呈现出中午高峰、上午和下午低谷的趋 势；另外几种行为节律性表现不明显。黑颈鹤越冬期主要行为的节律变化是受环 境温度变化影响的，温度高时黑颈鹤增加了修整时间减少了取食时间，而温度低 时则减少了修整时间增加了取食时间以维持能量需求，湿度是通过温度对黑颈鹤 产生影响的。每天黑颈鹤都随着太阳的升起开始觉醒，于07:18±0:15 飞离夜栖地， 大雾的天气影响了黑颈鹤的外出觅食，与之相适应的是黑颈鹤相应的推迟了出飞 时间。黑颈鹤所采取的所有行为都表现出了对大山包特殊环境的适应。 在大山包黑颈鹤所利用的栖息共有耕地（farmland）、草地（grassland）、沼泽 （marsh）和浅水水域（water area）四类。选择指数分析表明黑颈鹤对水域有极大 的偏好，其次为沼泽湿地，再次为耕地，而对草地表现为负选择，并且在越冬期 间的各月份之间，对不同栖息利用比率保持一致。这提示我们在进行保护区规划 的时候应该适当增加前三种栖息地的面积以满足黑颈鹤的越冬需求。主成份因子 分析表明黑颈鹤倾向于选择距夜栖地和水源较近、人流较少、干扰较小、无坡或缓坡的低海拔栖息地。处于不同越冬地的越冬黑颈鹤根据当地的实际情况采取不 同的栖息地利用，说明黑颈鹤具有较强的环境适应能力。 调查期间记录到了三只带有彩环的黑颈鹤个体，其中有两只佩戴有卫星发射 器，发射器编号分别为64309 和64311。大山包黑颈鹤种群数量变动的春季和秋季 高峰是由于处于不同越冬地的黑颈鹤迁徙造成的，同时也说明了大山包是在滇东 北和黔西北越冬的黑颈鹤的集散地。黑颈鹤的春季迁徙一般集中在3 月下旬至4 月上旬，在晴朗、微风的上午10:00-11:00 迁徙的黑颈鹤数量最多，说明了天气条 件对黑颈鹤迁徙的重要性。 大山包保护区内的高压输电电线和通信电缆对越冬黑颈鹤构成了极大的威 胁。观察期间共有7 只黑颈鹤因撞上输电电线而死亡，除去一只没有外伤的成体 之外，成幼比例为1:1，大都发生在天气较为恶劣的12 月-2 月之间。发生撞死黑 颈鹤的时候保护区内都有不同程度的大雾笼罩，由于大雾的影响造成可视条件下 降，加之黑颈鹤飞行的机动性差（翼载量大、展弦比不大），造成了黑颈鹤的伤亡.

Large-eddy simulation of flows past a flapping airfoil using immersed boundary method

The numerical simulation of flows past flapping foils at moderate Reynolds numbers presents two challenges to computational fluid dynamics: turbulent flows and moving boundaries. The direct forcing immersed boundary (IB) method has been developed to simulate laminar flows. However, its performance in simulating turbulent flows and transitional flows with moving boundaries has not been fully evaluated. In the present work, we use the IB method to simulate fully developed turbulent channel flows and transitional flows past a stationary/plunging SD7003 airfoil. To suppress the non-physical force oscillations in the plunging case, we use the smoothed discrete delta function for interpolation in the IB method. The results of the present work demonstrate that the IB method can be used to simulate turbulent flows and transitional flows with moving boundaries.

小麦中微量元素锌铁硒的含量的分析

本研究应用微波消解ICP-AES 法对62 个小麦品种及3 个地区土壤的锌铁硒含量进行了分析测定，发现不同小麦品种中微量元素含量差异很大，姊妹系间也存在差异。含铁量最高与最低的小麦品种铁含量相差29.68mg/kg。含锌量最高与最低的小麦品种锌含量相差46.70 mg/kg。含硒量最高与最低的小麦品种硒含量相差0.056 mg/kg。对不同地点的小麦及土壤中锌铁硒含量进行方差分析，发现双流和西昌两地种植小麦的铁含量和硒含量均有显著差异，西昌和荣县种植的锌含量有显著差异。在3 个地点中双流种植小麦硒含量最高，西昌种植小麦的铁和锌含量最高。 通过对小麦微量元素含量与土壤中微量元素含量进行了相关性分析，结果表明：小麦中的锌铁含量与土壤中的锌铁含量呈显著正相关，土壤中铁与锌含量呈极显著正相关，小麦中铁与锌含量也呈极显著正相关。随着土壤微量元素锌铁的提高，小麦中的锌铁元素含量同时提高，而且小麦对两种元素的吸收互相促进。土壤中的硒含量与锌铁含量呈负相关。小麦中硒含量也与锌铁含量也呈负相关。说明锌和铁与硒互相拮抗。小麦硒含量与土壤硒含量呈正相关，但不显著。表明土壤硒含量可以影响小麦硒含量，但不是决定因素，小麦硒含量与小麦自身因素有关。 对姊妹系G290（高硒含量）和G289（低硒含量）进行抗重金属胁迫和抗旱性实验发现，高硒品种G290的抗逆性优于低硒品种G289。 利用RAPD 技术对7 个姊妹系进行遗传差异分析发现，高硒材料G290出现了特异条带，分别标为1、2、3、4，其他姊妹系品种中未发现特异条带，回收4 条特异条带并连接转化，得到目的片段1、2、3 的重组子，进行测序。NCBI 中结果显示没有找到植物中的同源序列，说明特异序列可能是未发现的基因片段，推测可能与小麦硒含量有关，有待进一步研究。 以上研究结果，对小麦营养研究及功能性小麦的筛选和栽培具有指导作用。 In this study, we determinated the contents of zinc, iron, selenium in 62 wheat cultivars and soil samples of three regions by method of microwave digestion/ ICPAES,found that there was great difference of zinc, iron, selenium contents in different wheat cultivars as well as different sister lines. Iron content difference was 29.68 mg/kg between the highest-iron-content cultivar and the lowest one, and zinc content difference was 46.70 mg/kg , selenium content difference was 0.056 mg/kg. Anova analysis was made on contents of zinc, iron, selenium in wheat and soil samples of different locations, significant differences of Fe and Se contents were found between wheat in Shuangliu and Xichang, significant difference of Zn content was found between wheat in Xichang and Rongxian. Se content in wheat of Shuangliu was highest, Fe and Zn contents in wheat of Xichang were highest. Relativity analysis was made on three trace elements in Wheat and in soil, the result showed that there was significant positive correlation of zinc, iron content between in Wheat and in soil, as well as between Fe and Zn both in wheat and in soil. With the improving of Zn, Fe contents in soil, contents of Zn and Fe in wheat increased and absorption of Zn and Fe in wheat will mutual promote. Negative correlation of Se and Zn contents was found in wheat and soil, but not significant, that meant the antagonism of Se and Zn. Positive correlation of Se content in wheat and soil was found. High selenium content G290 and low selenium content G289 in sister lines were selected for heavy metal stress and drought resistance experiments, the result showed that the resistance of high-selenium-content cultivar was better than low selenium one. Analysis on genetic difference was made by RAPD, and specific bands were selected, marked 1,2,3,4, no more specific bands were found in other sister lines.4 bands were recovered, ligated to T-vector and transformed E.coli. Three recombinant plasmids were obtained and sequenced. NCBI Blast showed there was no homology with other plants. It implied that these fragments probably be new genes and maybe were related to selenium in wheat. It needs further research. This paper would be useful for the study of wheat nutrition as well as selection and cultivation of functional wheat.

重离子加速器中的软件无线电应用

This paper primarily elaborates automatic gain control design method in software radio receiver. It mainly uses in-phase and quadrature components quadratic sum to subtract the expectation of the output power to get the error statistic of the plus. The error statistic of the plus is smoothed by first order digital filter, and then is used to gain the output signals of controller. Thereby, it can make the system work well in certain dynamic region area of signals. It is designed for the Cooling Storage Ring ...中文文摘：本文主要阐述了软件无线电接收机中的相干AGC设计,主要利用了同相和正交支路的平方和与所期望的信号输出功率值相减,得到增益的误差统计量。该误差统计量经过一阶数字滤波器平滑,然后用于控制器输出信号的增益,从而使系统在一定的信号动态范围内都能工作。该设计主要用于兰州重离子加速器冷却存贮环的主环(CSRm)的重离子束团踢轨(Kicker System)的精确控制。

Low-temperature heat capacities and derived thermodynamic functions of cyclohexane

The low-temperature heat capacities of cyclohexane were measured in the temperature range from 78 to 350 K by means of an automatic adiabatic calorimeter equipped with a new sample container adapted to measure heat capacities of liquids. The sample container was described in detail. The performance of this calorimetric apparatus was evaluated by heat capacity measurements on water. The deviations of experimental heat capacities from the corresponding smoothed values lie within +/-0.3%, while the inaccuracy is within +/-0.4%, compared with the reference data in the whole experimental temperature range. Two kinds of phase transitions were found at 186.065 and 279.684 K corresponding solid-solid and solid-liquid phase transitions, respectively. The entropy and enthalpy of the phase transition, as well as the thermodynamic functions {H-(T)- H-298.15 K} and {S-(T)-S-298.15 K}, were derived from the heat capacity data. The mass fraction purity of cyclohexane sample used in the present calorimetric study was determined to be 99.9965% by fraction melting approach.

Calorimetric study and thermal analysis of berberine sulphate

The heat capacities of berberine sulphate [(C20H18NO4)(2)SO4.3H(2)O] were measured from 80 to 390 K by means of an automated adiabatic calorimeter. Smoothed heat capacities,{H-T-H-298.15} and {S-T-S-298.15} were calculated. The loss of crystalline water started at about 339.3+/-0.2 K, and its peak temperature was 365.8+/-0.6 K. The peak temperature of decomposition for berberine sulphate was at about 391.4+/-0.4 K by DSC curve. TG-DTG analysis of this material was carried out in temperature range from 310 to 970 K. TG and DSC curves show that there is no melting in the whole heating process.

Heat capacities and thermodynamic functions of p-chlorobenzoic acid

The heat capacities of p-chlorobenzoic acid were measured in the temperature range from 80 to 580 K by means of an automatic adiabatic calorimeter equipped with a small sample cell of internal volume of 7.4cm(3). The construction and procedures of the calorimetric system were described in detail. The performance of this calorimetric apparatus was evaluated by heat capacity measurements on alpha-Al2O3. The deviations of experimental heat capacities from the corresponding smoothed values lie within +/-0.28 per cent, while the inaccuracy is within +/-0.40 per cent, compared with the recommended reference data in the whole experimental temperature range. A fusion transition at T = 512.280 K was found from the C-p-T curve of p-chlorobenzoic acid. The enthalpy and entropy of the phase transition, as well as the thermodynamic functions {G((T)) - G((298.15))}, {H-(T) - H-(298.15)} and {S-(T) - S-298.15}, were derived from the heat capacity data. The mass fraction purity of p-chlorobenzoic acid sample used in the present calorimetric study was determined to be 0.99935 by fraction melting approach. (C) 2002 Elsevier Science Ltd. All rights reserved.