Research and Design of a Routing Protocol in Large-Scale Wireless Sensor Networks

无线传感器网络，作为全球未来十大技术之一，集成了传感器技术、嵌入式计算技术、分布式信息处理和自组织网技术，可实时感知、采集、处理、传输网络分布区域内的各种信息数据，在军事国防、生物医疗、环境监测、抢险救灾、防恐反恐、危险区域远程控制等领域具有十分广阔的应用前景。 本文研究分析了无线传感器网络的已有路由协议，并针对大规模的无线传感器网络设计了一种树状路由协议，它根据节点地址信息来形成路由，从而简化了复杂繁冗的路由表查找和维护，节省了不必要的开销，提高了路由效率，实现了快速有效的数据传输。 为支持此路由协议本文提出了一种自适应动态地址分配算——ADAR（AdaptiveDynamicAddre...As one of the ten high technologies in the future, wireless sensor network, which is the integration of micro-sensors, embedded computing, modern network and Ad Hoc technologies, can apperceive, collect, process and transmit various information data within the region. It can be used in military defense, biomedical, environmental monitoring, disaster relief, counter-terrorism, remote control of haz...学位：工学硕士院系专业：信息科学与技术学院通信工程系_通信与信息系统学号：2332007115216

Analysis of the Cool Down Related Cavity Performance of the European XFEL Vertical Acceptance Tests

For the European X-Ray Free Electron Laser (XFEL) cavity production, the cold radio-frequency (RF) test of the cavities at 2K after delivery from the two vendors was the mandatory acceptance test. It has been previously reported, that the cool down dynamics of a cavity across T$_c$ has a significant influence on the observed intrinsic quality factor Q$_0$, which is a measure of the losses on the inner cavity surface. A total number of 367 cool downs is used to analyze this correlation and we show that such a correlation is not observed during the European XFEL cavity production

Test Sequence for Superconducting XFEL Cavities in the Accelerator Module Test Facility (AMTF) at DESY

The European XFEL is a new research facility currently under construction at DESY in the Hamburg area in Germany. From 2016 onwards, it will generate extremely intense X-ray flashes that will be used by researchers from all over the world. The main part of the superconducting European XFEL linear accelerator consists of 100 accelerator modules with 800 RF-cavities inside. The accelerator modules, superconducting magnets and cavities will be tested in the accelerator module test facility (AMTF) at DESY. This paper gives an overview of the test sequences for the superconducting cavities, applied in the preparation area and at the two cryostats (XATC) of the AMTF-hall, and describes the complete area. In addition it summarizes the tests and lessons learnt until the middle of 2014

Nitrogen Infusion R&D on Single Cells at DESY

A first series of single cell cavities underwent the "Nitro-gen Infusion" treatment at DESY. Samples, which were inthe furnace together with the cavities, underwent a seriesof SEM/EDX measurements and showed some unexpectedstructures. In parallel, the cavity performance deterioratedafter the treatment. The furnace pressure and temperatureand the residual gases during the treatment were analyzed tofind the possible cause for the deterioration and next stepsto prevent this deterioration in following treatments are dis-cusse

Gas cooling of test masses for future gravitational-wave observatories

Recent observations made with advanced LIGO and advanced Virgo have initiated the era of gravitational-wave astronomy. The number of events detected by these ‘2nd generation’ (2G) ground-based observatories is partially limited by noise arising from temperature-induced position fluctuations of the test mass (TM) mirror surfaces used for probing spacetime dynamics. The design of next-generation gravitational-wave observatories addresses this limitation by using cryogenically cooled test masses; current approaches for continuously removing heat (resulting from absorbed laser light) rely on heat extraction via black-body radiation or conduction through suspension fibres. As a complementing approach for extracting heat during observational runs, we investigate cooling via helium gas impinging on the TM in free molecular flow. We establish a relation between cooling power and corresponding displacement noise, based on analytical models, which we compare to numerical simulations. Applying this theoretical framework with regard to the conceptual design of the Einstein telescope (ET), we find a cooling power of 10 mW at 18 K for a gas pressure that exceeds the ET design strain noise goal by at most a factor of ∼3 in the signal frequency band from 3 to 11 Hz. A cooling power of 100 mW at 18 K corresponds to a gas pressure that exceeds the ET design strain noise goal by at most a factor of ∼11 in the band from 1 to 28 Hz

Recent mid-T Single-Cell Treatments R&D at DESY

The challenge of improving the performance of SRF cavities is being faced worldwide. Oneapproach is to modify the superconducting surface properties through certain bakingprocedures. Recently a niobium retort furnace placed directly under an ISO4 clean room hasbeen refurbished at DESY. Thanks to an inter-vacuum chamber and cryopumps, with high purityvalues in the mass spectrum it is working in the UHV range of 2E-8 mbar. The mediumtemperature (mid-T) heat treatments around 300°C are promising and successfully deliverreproducible very high Q0 values of 2-5E10 at medium field strengths of 16 MV/m. Since thefirst DESY and ZRI mid-T campaign yielded promising results, further results of 1.3 GHz singlecellcavities are presented here after several modified treatments of the mid-T recipe. Inaddition, samples were added to each treatment, the RRR value change was examined, andsurface analyses were subsequently performed. The main focus of the sample study is theprecise role of the changes in the concentration of impurities on the surface. In particular, thechange in oxygen content due to diffusion processes is suspected to be the cause of enhancingthe performance

Nitrogen Infusion Sample R&D at DESY

Many accelerator projects such as the ILC would benefit from cavities with reduced surface resistance (high Q-values) while maintaining a high accelerating gradient. A possible way to meet the requirements is the so-called nitrogen-infusion procedure on Niobium cavities. However, a fundamental understanding and a theoretical model of this method are still missing. One important parameter is the residual resistance ratio (RRR) which is related to the impurity content of the material. We report the investigated RRR on samples in a wide temperature range in a vacuum and under a nitrogen atmosphere. This comparison made it possible to make statements about the differences in the concentration of nitrogen by varying the temperature. The samples are pure cavity-grade niobium and treated in the same manner as cavities. For this purpose, a small furnace dedicated to sample treatment was set up to change and explore the parameter space of the infusion recipe. Care was taken to achieve the highest level of purity possible in the furnace and in a pressure range of 1.0·10$^{-8}$ mbar in order to meet the high requirements of nitrogen infusion

Performance Analysis of the European XFEL SRF cavities, fromvertical test to operation in modules

More than 800 resonators have been fabricated, verti-cally qualified and operated in module tests before the accelerating module installation in the linac, which will be completed before the conference. An analysis of this experience, with correlation of the final cavity perfor-mances with production, preparation and assembly stages, is underway and at the time of the conference a summary of the activities will be available

Revamp and Reactivation of a Niobium Furnace at DESY

For research in the field of heat treatments of superconducting cavities, a Niobium ultra-high vacuum furnace built in 1992 – originally used for the titanisation of 1.3 GHz nine-cell cavities - and later shut down was revamped and reactivated. A significant addition is the ability to run the furnace in partial pressure mode with nitrogen. The furnace is connected directly to the ISO4 area of the clean room for cavity handling. At room temperature vacuum values of around 3e-8 mbar are achieved; at 1200°C the achieved pressure is 2.5e-7 mbar The revision included the replacement of the complete control system and a partial renewal of the pump technology. The internal mounting structures are optimized for single-cell operation including tandem operation consisting of two single-cell cavities and corresponding accessories such as samples and caps for the cavities. The installation of additional thermocouples for a detailed monitoring of the temperature curves is also possible at the mounting structure. Due to the furnace design, the location and the strict routines in handling, very high purity levels are achieved in comparison to similar set-ups and hence provide a mighty tool for SRF cavity R&D