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In this paper, the ponderomotive focusing forces are derived for a sheet electron beam in both periodic cusped magnetic and wiggler magnetic field configurations, which has a large aspect ratio, using two-time scale analytical method.
At millimeter wavelengths, there is a growing need for a small size and weight, high average power RF source. The sheet beam klystron (SBK) is ideally suited to many of these needs. The SBK is characterized by a large rectangular drift tube, which allows the use of a high current, low voltage beam, resulting in a low beam current density, and hence high efficiency and the possibility of PPM focusing.
However with China entering into the WTO, the big clearance in national seaport will soon realize, immigration traveler's number will be fast increasing, at the same time, anti-illegal immigrant conflict would also be more intense and complicated. Under such condition the analysis of anti-illegal immigrant intelligence has many difficulties. So data mining technology will be introduced in anti-illegal...
Wind erosion is an important environmental problem, thus researchers have used many methods to study it. The methods that have been used mainly involved theoretical analysis, experimental measurements under artificial conditions (e.g., in wind tunnels), and numerical simulations using a range of models. However, the results of these studies differ, and are not always satisfactory, particularly in...
Snow dynamic change is the hot issue of global climate change. Qilian Mountain located in the southern of Hexi Corridor, and is the sensitive and key area of climatic change in arid regions. Its snow's dynamic distribution has the important meaning to climatic change's influence and the response. Under the background of the climate warming, snow area of the Qilian Mountains has changed. This paper...
Freshwater environments contribute more than 20% of total CH4 flux to the atmosphere, and the lakes are one of the major natural sources of atmospheric CH4, mainly in boreal lakes. So, we present and analyze the temporal and spatial variations of CH4 VMRs over Lake Baikal, the only freshwater body, the unique large and high latitude lake, based on the retrieved monthly CH4 data from SCIAMACHY spectra...
DICOM standard is an indispensable component ofPACS, but due to non-DICOM images can be fast loaded and portable with compression, many non-DICOM medical imaging equipments are still widely used in the hospital system, which has led to existence of many non-DICOM medical images. However, the non-DICOM images are unsuitable for doctors to diagnose and study. In this paper, a low-load architecture is...
Graph Embedding (GE) along with its linearization outperforms the traditional linear dimension reduction techniques in face recognition, but there is still room for improvement on GE. This paper proposes an eigenvector weighting technique for a realization of linear GE, namely Neighbourhood Preserving Embedding (NPE) in face verification. The proposed method is called Eigenvector Weighting Function...
For most people, majority of their lives are spent in an indoor environment. With the improvement of living, indoor air pollution is impacting human health. In this paper, through analysis of sources and adverse health effects of several common indoor air pollutants, air pollutants are major contributing factors to chronic diseases and mortality. It should be treated urgently with the people's standard...
The sheet beam klystron (SBK) uses a high aspect ratio, thin rectangular beam to reduce space charge effects, increase power capability and beam-wave interaction efficiency. In this paper, a Rod model for the sheet beam was studied, and a 2.5D large signal program based on this model was developed to calculate the beam-wave interaction of SBK.
The paper has put forward an idea about the teaching reformation to course of probability and statistics in agriculture and forestry universities. We have paid attention to the theory contact with practice. We also present a new teaching method that the idea of mathematical modeling is applied in the teaching process of application cases to reform teaching methods and seek new teaching modes. Students'...
The diocotron instability of a relativistic sheet electron beam propagating through a uniform magnetic field is studied using a macroscopic cold fluid model. The general eigenvalue equation is obtained for low-frequency perturbations. In the limit of a long axial wavelength, a dispersion relation is derived for the special case of a sharp boundary density profile and used to study stability properties...
The proposed strategic procedure in the paper should provide a guideline for enterprises to develop their E-commerce strategy. It has been compiled by the author's training and experience of both management and technical issues. Six general steps are mainly discussed in this procedure: Making the initial decision to offer E-Commerce, Identifying the business aims for E-Commerce, Analyzing the feasibility...
Under the bottleneck of the resources and the environment, if the Western path of modernization is followed, the prospects of China will be dim. The volume of CO2 emission is huge and the growth has been fast in China, posing challenges for mitigation. The development of low-carbon economy is an inevitable choice for change strong. Market capacity, innovation capability and enterprises' fast transition...
Ozonation of dimethylamine (DMA), the most direct and common precursor of high carcinogenic disinfection by-product N-nitrosodimethylamine (NDMA), in aqueous solutions and in the presence of H2O2 was studied at ozone doses of 1.8 mg/L. The removal ratio of DMA increases from 46.7% to 77.1% with the dosage of H2O2 increasing from 0 to 1 mM, and the removal rate can be improved by increasing pH. According...
In order to solve the problem of "information isolated island" among e-government platform, it's urgent to build a safe, reliable, efficient, and stable platform for information sharing for resource integration of today's e-government. This paper analyses problems in the development of traditional e-government, describes the SOA (service-oriented architecture) and its related technologies...
Testing method by velocity of stress wave is widely used in the nondestructive testing system of strength of wood-based panel. Considering higher and higher requirement of accuracy on the testing system, the research developed testing system of stress wave velocity based on SCM in this paper. SCM is used as processing corn. The research calculated dynamic elastic modulus of wood-based panel, which...
A spurious-mode-suppressing method is introduced in this paper, aiming at increasing frequency interval between operating mode (TM310 mode) and spurious mode (TM020 mode). By means of CST-MWS, we find that the frequency interval can be increased 0.65 GHz in X-band by the method.
A spectrometer is used to measure numerical aperture (NA) of photonic crystal fibers (PCFs), and the high-precision result is obtained. We get the NA at any wavelength in 500∼900nm range, which is determined by light source and spectrometer. The measured results and theoretical calculation value match very well.
In this paper, the numerical aperture (NA) of photonic crystal fiber (PCF) is measured by a system with spectrometer, and high-precision results are obtained. The spectrometer can record the light intensity of different wavelengths. It overcomes the limitation that the traditional measurement can only measure the NA in some fixed wavelengths. We get the NA at any wavelength in 500nm∼900nm range, which...
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