立方反射镜失调特性的研究

结合理想坐标系下立方镜镜面微小倾斜后其三个平面法线坐标，利用刚体微量转动的反射法线向量公式，获得非理想立方镜反射矩阵；为了研究在光斜入射时镜面倾斜对出射光方向的影响，利用立方镜绕顶点旋转等效于光斜入射的方法，计算出光束夹角δ与单一镜面偏差角ε和立方镜旋转角θ之间的关系式；对于理想情况下的立方镜，利用几何光学可以证明出射光与入射光不但平行，而且过顶点作任意截面交于两光线所得的两个交点关于顶点对称，从而计算出立方镜绕顶点以外任意轴旋转造成出射光束相对原出射光的偏移量与旋转角关系式，理论计算值与实验数据吻合得很

Nutrient dynamics and the eutrophication of shallow lakes Kasumigaura (Japan), Donghu (PR China), and Okeechobee (USA)

We compared the nutrient dynamics of three lakes that have been heavily influenced by point and non-point source pollution and other human activities. The lakes, located in Japan (Lake Kasumigaura), People's Republic of China (Lake Donghu), and the USA (Lake Okeechobee), all are relatively large(>30 km(2)), very shallow (<4 m mean depth), and eutrophic. In all three lakes we found strong interactions among the sediments, water column, and human activities. Important processes affecting nutrient dynamics included nitrogen fixation, light limitation due to resuspended sediments, and intense grazing on algae by cultured fish. As a result of these complex interactions, simple empirical models developed to predict in-lake responses of total phosphorus and algal biomass to external nutrient loads must be used with caution. While published models may provide 'good' results, in terms of model output matching actual data, this may not be due to accurate representation of lake processes in the models. The variable nutrient dynamics that we observed among the three study lakes appears to be typical for shallow lake systems. This indicates that a greater reliance on lake-specific research may be required for effective management, and a lesser role of inter-lake generalization than is possible for deeper, dimictic lake systems. Furthermore, accurate predictions of management impacts in shallow eutrophic lakes may require the use of relatively complex deterministic modeling tools. (C) 2000 Elsevier Science Ltd. All rights reserved.

AMPS modeling of light J-V characteristics of a-Si based solar cells

AMPS (Analysis of microelectronic and photonic structures) mode,which was developed by Pennsylvania State University, has been used to module the light J-V characteristics of a-Si solar cells with a structure of TCO/p-a-SiC:H/i-a-Si:H/n-a-Si:H/ metal. The effects of valence band offset and contact barriers at p/i and TOC/p, n/metal interfaces on the light J-V characteristics have been examined. The modeling has qualitatively categorized and explained the non-ideal J-V behaviors (rollover, crossover, Voc shift,and rollunder) observed in a-Si based solar cells.

Space-charge-limited currents in GaN Schottky diodes

Unusual dark current voltage (I-V) characteristics were observed in GaN Schottky diodes. I-V characteristics of the GaN Schottky diodes were measured down to the magnitude of 10(-14) A. Although these Schottky diodes were clearly rectifying, their I-V characteristics were non-ideal which can be judged from the non-linearity in the semi-logarithmic plots. Careful analysis of the forward bias I-V characteristics on log-log scale indicates space-charge-limited current (SCLC) conduction dominates the current transport in these GaN Schottky diodes. The concentration of the deep trapping centers was estimated to be higher than 10(15) cm(-3). In the deep level transient spectra (DLTS) measurements for the GaN Schottky diodes, deep defect levels around 0.20 eV below the bottom of the conduction band were identified, which may act as the trapping centers. The concentration of the deep centers obtained from the DLTS data is about 5 x 10(15) cm(-3). SCLC measurements may be used to probe the properties of deep levels in wide bandgap GaN-AlGaN compound semiconductors, as is the case with insulators in the presence of trapping centers. (c) 2005 Elsevier Ltd. All rights reserved.

近地表土壤水分条件对坡面农业非点源污染物运移的影响

采用人工模拟降雨实验,研究了近地表土壤水分条件,尤其是土壤水分饱和条件对土壤侵蚀过程中农业非点源污染物运移的影响.结果表明,前期近地表土壤水分条件对土壤侵蚀过程中农业非点源污染物的迁移有着很大影响.饱和含水量时径流及泥沙中非点源污染物的流失浓度和流失量大于非饱和含水量,且前期近地表土壤含水量越大,径流及泥沙中农业非点源污染物的流失浓度和流失量越大.土壤氮素的主要流失途径是降雨所产生的径流,约占总流失量的90.4%～99.8%;土壤磷素的流失途径是降雨径流和侵蚀产沙,分别占总流失量的2.67%～23.5%和76.5%～97.3%.同时,土壤质地对磷素养分的流失有很大影响,杨凌土随泥沙流失的DP浓度和流失量均大于安塞黄绵土.最后,提出了采取最佳管理措施等控制农业非点源污染的针对性建议.

分布式水文模型的误差分析

分布式水文模型以其具有明确物理意义的参数结构和对空间分异性的全面反映,能够准确详尽地描述和模拟流域内真实的降水径流过程而被广泛需求和关注。在模拟土地利用、土地覆盖、水土流失等各种变化过程的水文响应,面源污染、陆面过程、气候变化影响评价等诸多领域都有广泛的应用。模型的预报精度和误差至关重要,决定了模型的应用和推广。在分析分布式水文模型建立和验证过程的基础上,提出了模型的4类误差来源:被排除在外的因素引起的误差,实测历史记录资料的随机或系统误差,参数误差和模型结构误差,讨论了各类误差的分析与计算方法,为模型的发展和成长提供了依据。

1.55μm Fabry-Perot Thermo-Optical Tunable Filter with amorphous-Si as Cavity

A 1.55μm Fabry-Perot (F-P) thermo-optical tunable filter is fabricated. The cavity is made of amorphous silicon (a-Si) layer grown by electron-beam evaporation technique. Due to the excellent thermo-optical property of a-Si, the refractive index of the F-P cavity will be changed by heating; the transmittance resonant peak will therefore shift substantially. The measured tuning range is 12nm, FWHM (full-width-at-half-maximum) of the transmission peak is 9nm, and heating efficiency is 0.1K/mW. The large FWHM is mainly due to the non-ideal coating deposition and mirror undulation. Possible improvements to increase the efficiency of heating are suggested.

亚硝化—厌氧氨氧化处理猪场废水研究

猪场废水COD浓度高、氨氮浓度高、悬浮物浓度高，已成为农村面源污染的主要来源，并严重威胁到农村饮用水安全。猪场废水氨氮浓度高、处理难度大，如何采用经济高效的方法，去除氨氮使其达到排放标准，一直是猪场废水处理中面临的重要难题。 厌氧氨氧化是近年受到国内外水处理研究者广泛关注的新型生物脱氮技术，具有不需要外加有机碳源、节省供氧量、降低能耗等优点。虽然国内外研究者对厌氧氨氧化过程的脱氮机理、厌氧氨氧化菌的生理生化特性等进行了多方面的研究，但已有的报道大多以模拟废水为研究对象，以猪场废水为研究对象的报道，在国内外文献中极少有报导。 本论文以猪场废水为主要研究对象，考察了猪场废水的亚硝化过程、厌氧氨氧化的启动过程，并对亚硝化和厌氧氨氧化联合用于猪场废水脱氮进行了探索。 1．论文首先研究了猪场废水的亚硝化过程，考察了废水水质和主要运行条件对亚硝化过程的影响。实验表明：（1）亚硝化阶段反应时间为8到10h时，出水中氨氮和亚硝酸盐浓度比可达到1：1～1：1.23，满足厌氧氨氧化反应对二者比例的要求；达到前述要求时，氨氮去除率达到58.3～65.6 %，亚硝化率在整个过程均保持在97 %以上，COD去除率在59.2～68.6 %；（2）曝气量（溶解氧）对亚硝化过程影响显著，随着曝气量增大，达到厌氧氨氧化要求的氨氮与亚硝酸盐氮浓度比例所需水力停留时间τ越短，pH出现明显下降的时间越短；（3）τ对应的pH在7.8～8.1之间，无需进行pH调节即可满足厌氧氨氧化反应对pH的要求；（4）氨氮和COD降解过程遵循一级反应动力学，氨氮和COD降解的速率常数分别为0.0656～0.0724 1/h和0.0491～0.0664 1/h。 2．在进行亚硝化过程研究的同时，以模拟废水为试验对象，进行厌氧氨氧化启动研究。以反硝化污泥和养殖厂储水池厌氧底泥的混合污泥作为接种污泥，历时大约100天，培育出具有厌氧氨氧化活性的污泥，氨氮和亚硝酸盐氮最高进水浓度分别为223.8 mg/L和171.4 mg/L，去除率最高分别达48%和41.5%，此时二者消耗比例为1.33：1。 3．在猪场废水的亚硝化研究完成和厌氧氨氧化过程初步启动成功后，在模拟废水中逐步加入猪场废水的亚硝化处理出水，逐步实现亚硝化和厌氧氨氧化的组合。亚硝化出水添加到厌氧反应器后，厌氧氨氧化反应仍可继续进行，且去除效率逐步提高。研究发现添加的亚硝化出水中携带的亚硝化细菌在厌氧氨氧化菌膜外层生长并累积，增加了厌氧氨氧化反应基质的传质阻力，妨碍了厌氧氨氧化效率的提高。 4．亚硝化－厌氧氨氧化实际工程应用探索中，生物接触氧化池可在有效去除废水中的有机物的同时实现亚硝化，出水中氨氮和亚硝酸盐比例平均为1.10，可满足后续厌氧氨氧化的要求；在适宜的进水浓度和温度下，ABR池出现了厌氧氨氧化启动的迹象；研究同时发现，水质的波动和气温的变化是工程中影响厌氧氨氧化菌活性的重要因素。 论文的主要创新点在于：（1）以猪场废水为研究对象，以实现厌氧氨氧化为目标，对亚硝化过程进行了比较详细的考察，获得了亚硝化出水满足厌氧氨氧化要求的工艺条件，通过对其COD和氨氮降解过程的考察，得出亚硝化阶段COD降解和氨氮去除的动力学模型；（2）对亚硝化－厌氧氨氧化处理猪场废水进行了探索，确立了影响其污染物去除率稳定的重要因素。 论文的上述研究成果，为厌氧氨氧化技术的实用性研究提供理论依据。 Piggery wastewater, which is characterized by high concentration of COD、ammonium and suspend substance, has become a most important source of non-point source pollution and also severely threats drinking water security in rural area. How to discharge piggery wastewater with the ammonium concentration meeting standard by economical and effective method? This is the most urgent problem in piggery wastewater treatment. As a new biological nitrogen removal technology, Anammox process has been paid more and more attention by researchers all over the world. Anammox has advantages of no need of organic carbon addition, low oxygen consumption and energy consumption. Plenty of investigations have been carried out to the mechanism, physiological and biochemical characteristic of bacteria about Anammox. Most of researches focused on synthetic wastewater, there is rare report about its application in piggery wastewater. In this paper，experimental studies were performed to investigate Sharon process in treatment of piggery wastewater，the start up process of Annammox using synthetic wastewater were studied, the feasibility of applying Sharon-Anammox process in the nitrogen removal of piggery wastewater was evaluated. 1. Sharon process of piggery wastewater was firstly investigated to analyze the effects of water quality and main running parameters, which meet the NH4+-N to NO2--N ratio requirement of successive Anammox. Results showed: (1)During Sharon Process，after 8～10 hours’ reaction the NH4+-N to NO2--N ratio in effluent reached 1:1.0～1:1.23, when the removal percentage of NH4+-N was 58.3～65.6 %, a semi-nitration rate of above 97 % was achieved during the process; meanwhile 59.2～68.6 % of the COD was also removed. (2)The aeration rate（oxygen） had obvious effect on the hydraulic retention time(τ) which met the NH4+-N to NO2--N ratio requirement of Anammox. As aeration rate increased, the hydraulic retention time(τ) was shortened. (3) The pH corresponding to τ was between 7.8 and 8.1, thus it needed no artificial adjustment. (4) The reduction of ammonia and COD followed the first-order reaction kinetics. The velocity constants of ammonia and COD were 0.0656～0.0724 1/h and 0.0491～0.0664 1/h, respectively. 2. The startup of Anammox process using the artificial wastewater was performed simultaneously with Sharon. The aim was to investigate the running parameters of Anammox and make foundation for the combination stage. By using the mixture of denitrifying sludge and anaerobic sludge in tank of the breeding factory, sludge of Anammox activity was cultivated in UASB after 100 days. The removal percentage of NH4+-N and NO2-N were up to 48% and 41.5%, respectively, when the NH4+-N and NO2-N influent concentration were 223.8 mg/L and 171.4 mg/L, respectively, the NH4+-N and NO2-N removal rate was 1.33:1. 3. After investigation of Sharon and startup of Anammox, effluent of Sharon process was added into the synthetic wastewater to combine Sharon and Anammox step by step. It took some time after the addition of Sharon effluent that Anammox reaction continued and the removal rate kept increasing. It indicated that nitrifying bacteria were carried by the Sharon effluent cumulated in the outer layer of Anammox. This enhanced transfer resistance of Anammox reaction and the increasing removal rate was restrained. 4. In the bio-contact oxidation pond of practical project, Sharon process were carried out successfully and organic compounds were removed effectively. An average NO2-N/ NH4+-N rate of 1:1.0 was achieved in the effluent, which met the requirement of successive Anammox. Under condition of suitable influent concentration and temperature, there was evidence that Anammox could start up in ABR. The variety of wastewater and temperature had great affects on Anammox activity in practical engineering. Innovation of this paper: (1) The Sharon process for treating piggery wastewater was discussed in details. Technological parameters that met requirement of Anammox were obtained. The dynamic models of COD and ammonium removal in the process were educed. (2) Sharon-Ananmmox for treatment of piggery wastewater was investigated, and the primary influencing factors was studied. This paper could be a theoretical consult for research of Anammox utility.

非点源污染物细颗粒泥沙的絮凝-分散研究

细颗粒泥沙的絮凝-分散对土壤结构的稳定性，土壤中农用化合物的迁移以及侵蚀泥沙的输移、沉积有重要作用。文章概述了影响细颗粒泥沙絮凝-分散的几种主要因素——电解质种类及其浓度，矿物组成，有机质含量，pH值以及水流紊动等；指出了当前研究中存在的不足之处。

黄土高原淤地坝土壤性质剖面变化规律及其功能探讨

为分析淤地坝土壤性质的剖面变化规律及其在非点源污染工程治理方面的可能性,采用经典统计学方法研究了黄土高原典型淤地坝土壤性质在5.20 m剖面上的变化规律,并探讨了淤地坝作为碳储存库以及养分富集库的独特功能.结果表明,①坝前土壤剖面容重、砂粒含量低于坝尾,而土壤含水率、有机碳、粘粒、粉粒、速效磷、硝态氮以及铵态氮均大于坝尾;容重随剖面的变异情况为弱变异性,其余指标为中等变异性;除坝前砂粒含量和坝尾土壤含水率外,其余指标均呈正态分布;②坝前和坝尾剖面土壤含水率随土层深度的增加均呈锯齿型变化趋势,在剖面上的分布表现为波动型;土壤有机碳、速效磷、铵态氮随剖面的变化规律与土壤水分的趋势相同;③除坝尾容重与硝态氮、铵态氮及速效磷与铵态氮的相关性未达到显著水平外,土壤含水率、有机碳、容重、粘粒、粉粒、砂粒、速效磷、硝态氮以及铵态氮之间的相关性均达到了显著水平(p<0.05),并且坝前与坝尾剖面土壤各个性质之间所表现的正相关性或负相关性是一致的;④淤地坝作为黄土高原的一个重要碳储存库,坝前有机碳储量高于坝尾,且坝前在400~520 cm储量最高,坝尾在0~100 cm储量最高;⑤淤地坝对速效养分具有富集效应,坝前储量大于坝尾...

Land use and water quality response in the northern region of Changxing County

In this paper, taking the northern region of Changxing County for example, with ammonia nitrogen as a pollution assessment index, we used an improved export coefficient method for estimate polluting load of non-point source pollution (NSP) and the social pollution survey data in the study area to estimate point source pollution. By comparing the total pollution output and the national surface water environmental quality standards find that the whole study area achieves the second water quality standard. However, Jiapu Township exceeds the water quality standards seriously because of the superfluous point source pollution. The water quality of other Townships is good. Further analysis showed that different types of land use and proportions in the northern region of Changxing County have a significant impact on the non-point source pollution, the general law is farmland contributes the largest share of the non-point source pollution output, followed by residential area and bare land, besides, with the increase in the proportion of forest and the decrease of farmland and residential area, the non-point source pollution reduces gradually. © 2010 IEEE.

A Cip/Multi-Moment Finite Volume Method For Shallow Water Equations With Source Terms

A novel finite volume method has been presented to solve the shallow water equations. In addition to the volume-integrated average (VIA) for each mesh cell, the surface-integrated average (SIA) is also treated as the model variable and is independently predicted. The numerical reconstruction is conducted based on both the VIA and the SIA. Different approaches are used to update VIA and SIA separately. The SIA is updated by a semi-Lagrangian scheme in terms of the Riemann invariants of the shallow water equations, while the VIA is computed by a flux-based finite volume formulation and is thus exactly conserved. Numerical oscillation can be effectively avoided through the use of a non-oscillatory interpolation function. The numerical formulations for both SIA and VIA moments maintain exactly the balance between the fluxes and the source terms. 1D and 2D numerical formulations are validated with numerical experiments. Copyright (c) 2007 John Wiley & Sons, Ltd.

Behavior of ar plasma formed in a high-density plasma source - an ecr reactor

In order to develop the ultra-large scale integration(ULSI), low pressure and high density plasma apparatus are required for etching and deposit of thin films. To understand critical parameters such as the pressure, temperature, electrostatic potential and energy distribution of ions impacting on the wafer, it is necessary to understand how these parameters are influenced by the power input and neutral gas pressure. In the present work, a 2-D hybrid electron fluid-particle ion model has been developed to simulate one of the high density plasma sources-an Electron Cyclotron Resonance (ECR) plasma system with various pressures and power inputs in a non-uniform magnetic field. By means of numerical simulation, the energy distributions of argon ion impacting on the wafer are obtained and the plasma density, electron temperature and plasma electrostatic potential are plotted in 3-D. It is concluded that the plasma density depends mainly on both the power input and neutral gas pressure. However, the plasma potential and electron temperature can hardly be affected by the power input, they seem to be primarily dependent on the neutral gas pressure. The comparison shows that the simulation results are qualitatively in good agreement with the experiment measurements.

Single-photon source in strong photon-atom interaction regime in quasiperiodic photonic crystals

The antibunching properties of the fluorescence from a two-level ideal system in a 12-fold quasiperiodic photonic crystal are investigated based on the calculated local density of states. We found that the antibunching phenomenon of the fluorescence from two-level ideal systems could be significantly changed by varying their positions, i.e., perfect antibunching and antibunching with damped Rabi oscillation phenomenon occurred in different positions and at different frequencies in photonic crystals as a result of the large differences in the local density of states. This study revealed that the multi-level coherence of fluorescence from a two-level ideal system could be manipulated by controlling the position of the two-level ideal system in photonic crystals and the emission frequency in the photonic band structure. Copyright (C) EPLA, 2008

10 Gbit s(-1) electroabsorption-modulated laser light-source module using selective area MOVPE

A distributed-feedback (DFB) laser and a high-speed electroabsorption (EA) modulator are integrated, on the basis of the selective area MOVPE growth (SAG) technique and the ridge waveguide structure, for a 10 Gbit s(-1) optical transmission system. The integrated DFB laser/EA modulator device is packaged in a compact module with a 20% optical coupling efficiency to the single-mode fibre. The typical threshold current is 15 mA, and the side-mode suppression ratio is over 40 dB with the single-mode operation at 1550 nm. The module exhibits 1.2 mW fibre output power at a laser gain current of 70 mA and a modulator bias voltage of 0 V. The 3 dB bandwidth is 12 GHz. A dynamic extinction ratio of over 10 dB has been successfully achieved under 10 Gbit s(-1) non-return to zero (NRZ) operation, and a clearly open eye diagram is obtained.