土壤微生物碳素利用效率(CUE)是指微生物将吸收的碳(C)转化为自身生物量C的效率,也称为微生物的生长效率.土壤微生物CUE是生态系统C循环中的重要生理生态学参数,影响着生态系统的C固持、周转、土壤矿化以及温室气体排放等过程.在全球环境变化背景下,认识土壤微生物CUE的变异及其影响机制,对于更好的认识生态系统C循环过程及其对全球变化的响应具有重要意义.概述了CUE的定义及其测定方法,重点综述和分析土壤微生物CUE的变异及影响因素取得的研究进展.基于现有研究的分析得出,土壤微生物CUE通常表示为微生物的生长与吸收的比值,分为基于微生物生长速率、微生物生物量、底物吸收速率和底物浓度变化等方法进行测定.土壤微生物CUE在0.2-0.8的范围内变化,这种变异主要受到来自热力学、生态环境因子、底物养分质量和有效性、化学计量平衡以及微生物群落组成的影响.今后土壤微生物CUE的研究应加强对微量代谢组分的定量分析,生物和环境要素交互影响的调控机理解析,以及微生物动态生理响应过程的碳循环模型优化.

为明晰植被冠层叶绿素荧光遥感信息与总初级生产力(Gross Primary Productivity,GPP)间关系,以提高GPP估算精度,该文以典型C3(冬小麦)和C4(夏玉米)作物为例,利用不同传感器采集高频率光谱数据,提取了红光区和远红光区作物冠层日光诱导叶绿素荧光(Sun-induced chlorophyll Fluorescence,SIF)遥感信息.结合通量观测数据,分析了SIF与GPP的日变化特征,并探讨了基于SIF估算作物GPP的能力和差异性.结果表明:1)C3、C4作物的GPP日变化特征差异明显,前者呈"双峰"特征,后者呈"单峰"特征;而SIF760和SIF687均呈现明显的"单峰"特征,即早晚低、午间高;2)不同类型传感器对SIF数值大小的影响强于对其日变化特征的影响,同时,低光谱分辨率传感器对SIF687具有明显的高估现象,且对C3作物的高估强于C4作物;3)C3、C4作物SIF760和SIF687均与冠层吸收光合有效辐射(Absorbed Photosynthetic Active Radiation,APAR)呈显著的线性正相关关系(R2>0.8),可以直接用于APAR产品的反演;4)针对远红光区SIF,单日观测数据分析结果表明,C3、C4作物SIF760与GPP呈显著的线性正相关关系(R2>0.6),而基于多日观测数据构建的非线性对数关系模型优于线性关系模型;针对红光区SIF,无论是基于单日还是多日观测数据,C3、C4作物均适宜采用一种非线性对数关系模型来估算GPP(R2>0.7),且模型更为稳健.

NLSR is a routing protocol designed for NDN,but still cannot deal with the problem raised by source mobility.This paper proposed an optimized NSLR-SMmechanism to cope with the problem caused by source mobility.In NLSR-SM,the mo-bile source reported its movement information before it moved to another AP.Other nodes updated their FIBs based on this in-formation in advance.It developed a discrete-event simulator on ndnSIM to validate the effectiveness and feasibility of the NLSR-SM.In addition,it compared NLSR-SM with its original mechanism.The results show that NLSR-SM can reduce the round-trip-time and improve the responding ratio under different network conditions.NLSR-SM can effectively deal with the source mobility problem in NDN.

The storage and lookup of Open Flow flow tables still faces many challenges such as the increasing number of fields in flow inlets, the explosive growth of flow scales, and difficulties in achieving wired-speed processing of ports in Open Flow switches. To solve these problems, this paper presents an efficient storage and lookup method for flow tables in Open Flow. This method divides flow tables into multiple sub-flow tables of smaller scale and fewer matching fields. Based on the different types of matching fields, sub-flow tables are split into multiple slices, which can be handled by different algorithms and hardware. The matching result of sub-flow tables can be obtained using the matching results of slices in sub-flow and summary tables. By splitting the flow and sub-flow tables, this method compresses the storage space of the flow table in Open Flow switches. By optimizing of subflow table selection and lookup processes, this method reduces the cost of hardware resources when executing the lookup process. Extensive simulation experiments show that the proposed method can compress storage space by about 50% and can reduce hardware resource consumption to 80% when executing matching processes.

现有移动切换的相关研究方案在实际部署时配置繁琐、工作量大、网络运维成本高,有些方案还存在三角路由问题,导致切换时延增大.为了解决移动切换过程中的这些问题,提高移动切换的性能,提出了一种基于OpenFlow的移动切换框架,通过理论分析证明了该切换框架的可行性;另外,通过搭建基于OpenFlow的移动切换实验平台,与传统移动IP方案进行性能对比分析.实验结果显示,基于OpenFlow的移动切换框架能够有效地控制数据流路径,避免三角路由问题,并且较传统方案其切换时延降低,说明提出的移动切换框架能够有效节省网络带宽资源和优化移动切换效率.

Contemporary CCD especially the scientific grade CCD dynamic range is up to 100,000 electrons,and even capacity over 100,000 electrons.In order to take full advantage of these characteristics,it is necessary that the dynamic range of Analog-to-Digital Converter(ADC) must exceed the dynamic range of the CCD.The number of bits provided by the ADC must exceed 16 bits,while the high reliability and inexpensive 18?20 bit A/D converter is few.Firstly,we analyze CCD noise,and then the principle to extend the dynamic of the CCD in signal processing chain is presented using two low resolution ADC with different sensitivity.Then,we present a concrete example of improving the resolution of the ADC by two parallel low resolution ADCs.Finally,the laboratory imaging test results show that two low-resolution ADCs are used by combining raw quantization with fine quantization to achieve a high resolution,and improve the dynamic range of CCD camera.

PCIE-1429 acquisition card doesn′t support data acquisition synchronously of tow cameras.To solve this problem,a high-speed data acquisition system based on LabVIEW is designed,the dynamic link library with function of data detaching by VC++is created,and LabVIEW is adopted to call the DLL,a data detaching scheme of double cameras acquisition is achieved.Experiment proves that continuous data acquisition with PCIE-1429 acquisition card under "double-base mode",And it has advantages of expeditious,effective,stable and operating expediently.

In order to improve performance of CCD(charge coupled device) at low light levels,a new technique of eliminating readout noise is presented after analyzing the short of classical technique,namely,correlated double sampling.First,the primary kinds of noise in CCD are analyzed,and then a platform for generating and analyzing the noise in CCD is established.An array of proper numbers can be found to be used in the practical filter circuit from the result obtained by the platform under low light level.Therefore,the reset noise of CCD can be eliminated more efficiently than classical technique and any other noise passes doesn't introduced through digital filter.

The direct discharge of anaerobically digested piggery wastewater from many large-scale pig farms causes a serious secondary pollution. The anaerobically digested piggery wastewater is difficult to be treated due to high content of refractory organic pollutants and carbon/nitrogen ratio imbalance. The combined process of hydrolysis, biological contact oxidization (O_1), anaerobic biofilm and biological contact oxidization (O_2) was applied to treat anaerobically digested piggery wastewater. At normal temperature and without addition of any chemicals, a stable short-cut nitrification and denitrification is achieved.When the hydraulic load is about 0.45m~3/(m~2·d),the removal rates of COD and ammonia nitrogen are 78% to 85% and 79% to 87% respectively, and the nitrosation rate is more than 99%. The combined process provides an effective way for biological treatment of wastewater with high ammonia nitrogen concentration and low carbon/nitrogen ratio.

本文采用室内构建的小型人工湿地,开展了低放污水中放射性核素钚-239的去除研究.初步研完表明,当实验进水钚-239活度为1.8～2.8×102Bq/L的条件下,该系统稳定运行6周内对供试低放污水中钚-239的平均去除率可迭95%以上,湿地出水中钚-239的活度低于7.0Bq/L.

Through discussing the video signal processing method for the traditional CCD observation camera,a newly signal processing circuit solution centered on VSP2212-high integrated special CCD video processing chip was designed.All the associated debugging of hardware and software were accomplished.The results of simulation and experiments show that the system is with high integration,low consumption,stable operation and low noise,making a better basis for the designed CCD observation camera system to develop into a light and compact system.

The object is to get a design of high-dependability MCU IP soft core which meet the demand of electronic equipment for aerospace.With analysis of the theory of single event upset and summary of technology to design a high-dependability system,a modification on mc8051 IP core from oregano systems have been done.The MCU IP core meet the aims of the design and it runs smoothly.The final result shows that:this design proposal is reasonable and simple to achieve,and with application value too.

As a well developed water purification technology,biological contact oxidization pond has been widely researched and applied in river purification and remediation.Synthetic wastewater simulating village non-point source sewage is effectively purified in a laboratory biological contact oxidization pond system.Steady COD and ammonia nitrogen removal can be achieved at 85% and 79% respectively on the average in 11 weeks,when the concentration of COD and ammonia nitrogen is 130 to 290 mg/L and 30 to 40 mg/L,and the hydraulic loading is 0.19 to 0.24 m3/(m2·d).

According to frame transfer CCD, CCD driving circuit was detailed introduced. CCD driving schedule using the programmable logical device of the EPM7160SLC84-10 was designed. Bias voltage was designed by adjustable regulator LM117. CCD driving circuit was designed by specific driving chip. Designing of CCD driving circuit can meet the frame transfer CCD’s demand.

The principle of CCD(Charge Coupled Devices) and the characteristic of CCD output signal are introduced. Then the application of VSP2212 and the chip which designed primarily for CCD video signal processing also are introduced.

CMOS图像传感器在许多领域取得了广泛的应用.选用IBIS5-A-1300作为大面阵高帧频CMOS图像传感器,通过FPGA实现对视频系统的控制并采用USB2.0作为高速数据接口接收主机指令和传输图像数据.提出了一个完整的采用CMOS图像传感器的数字视频系统设计方案.

The space environment commands special performances in power, cubage, radiation and so on. CMOS imaging sensor fits in with the requirement of applications of space technology for its advantages in power, integration and radiation. A project of digital camera system with CMOS imaging sensor applicated in space technology is adviced.

The reliability of the single-chip computer system was improved by redundancy technique . Redundancy technique was divided into hardware redundancy and software redundancy. This paper discuss these hardware and software redundancy technique.

There are introduced the principle of low voltage differential signals and its typical application. Some rule when apply LVDS into circuit design are discussed.

When adopting mode-locked Nd:YAG laser to choose single pulse, KD~ *P Pockels cell is usually used. The half wavelength voltage is 6.6 kV to the laser of 1.06μm wavelength. In recent years, cold cathode thyratron KN-22 is widely used in circuit, but here KN-22 is replaced by MOSFET. The circuit with MOSFET has stable and credible performance, it can output a pulse of -6.6～-8kV and the pulse width can be adjusted from 5ns to 10ns. The circuit has a short time jitter (0.5ns), a delay of 30ns and high probability of selecting single pulse (100%). No abnormity is found after using a long time and the circuit can be also used as chopper and pulse shearer.