Search

We present a compact diode-pumped Tm/Ho:YLF laser, via integrating the Tm-doped and Ho-doped YLF crystals into a single bulk gain medium. Gain spectral model was developed first to the predict the potential Tm:YLF laser wavelength using different types of output coupling, for enhancing resonant absorption of the Ho:YLF crystal. Further verification were carried out by intra-cavity pumping the Ho:YLF laser with a Tm:YLF laser, where maximum output power of 11.3 W at 2.06 μm with near diffraction limited beam quality was obtained with conversion efficiency of 28.2% by considering the incident 793 nm diode power. In the Tm/Ho:YLF laser, maximum output power of 10.2 W at 2063 nm with power instability of 0.55% was obtained, corresponding to a slope efficiency of 29.6 % and optical conversion efficiency of 25.5%. The results provide a compact, accessible, and efficient Ho laser scheme, with has potential applications in wind lidar, surgeries, material processing, and nonlinear frequency conversion toward the mid-infrared region.

In recent years, with the rapid development of computer technology, 3D reconstruction technology has gradually entered people’s lives. 3D reconstruction is one of the more popular research directions in the field of computer vision. Three-dimensional reconstruction mainly studies the process of how to obtain three-dimensional information based on single-view or multi-view reconstruction. With the growing demand for computers to automatically obtain three-dimensional information of the surrounding environment, the practical application requirements for three-dimensional reconstruction technology are also getting higher and higher. Therefore, how to quickly and efficiently reconstruct 3D models has become an important research topic in the field of computer vision. In view of this practical application problem, this paper starts from the perspective such as Structure from Motion,Clustering Multi-view Stereo,Patch-based Multi-View Stereo and other aspects, and use the learning-based method to match the sift feature points. In this paper, we mainly research on several key technologies in the 3D reconstruction process.

In order to practice bus city planning, it is of great significance to construct a reasonable urban bus service system. At present, there are various research models and methods, and a city bus service quality evaluation model is established based on the advantages and disadvantages of various methods. Analytic hierarchy process and coefficient of variation method were combined to form subjective and objective weights, and cloud model was established for comprehensive quality evaluation. The feasibility of the model is verified by the measured indexes of public transportation in Luoyang City, which proves the rationality of the evaluation method and provides reference for other cities.

On the basis of analysing and defining the industry classification of logistics information service industry, select the statistical data of logistics information service industry and three industries in China in 2017, use the grey relational analysis method to analyse the related interactive development of logistics information service industry and three industries in different provinces with different economic development levels in China, reveal the objective requirements of the development of China’s logistics information service industry.

Non-uniform illumination makes it's difficult to detect and extract the target. To locate multiple target under complicate illumination, an improved vision system was designed in this paper. After analyzed kinds of image-binaryzation strategy, we choose the adaptive threshold binarization as the image binarization strategy. Through image processing, morphological processing, adaptive threshold binarization and contour detecting algorithm, a vision system have been designed out on the platform of Virtual Studio 2013. Experiment shows that vision system can locate multiple target efficiently under non-uniform illumination.

This paper addresses an improved water-body extraction method by the multispectral remote sensing image of four-bands. Firstly, traditional multispectral water body extraction technologies are reviewed, and their features are compared. It shows that finding the most difference of the reflection ratio of the water body and the background is the core to improve the identification rate. Furthermore, combing data's feature of GF-01 and GF-02 satellites, an improved normalization index method by introducing the weighted average of the blue and green light bands was proposed. Finally, the comparative results illustrating the improvement of water body extraction are provided and analyzed.

A stable high-repetition-rate, high pulse energy and single-frequency electro-optic Q-switched laser has been developed and demonstrated in this paper. The prelase technique has been used in this single-frequency laser. And a PID feedback control electronics is applied to stabilize the prelase. Meanwhile, a two-plate resonant reflector take the place of traditional dielectric output coupler mirror to enhance the single-axial-mode selection. And a Cr:YAG saturable absorber is also inserted in the cavity to improve single-axial-mode selection. Output laser power over 2 W with 10 ns pulse duration has been obtained at a repetition rate of 1 kHz. And the single-axial-mode probability was 100% in one hour without any manual adjustments. The experimental results show that the prelase technique is reliable to attain single-frequency operation.

The track periodical irregularity is the main external excitation source for the maglev train suspension system. This kind of excitation degrades the stability of the levitation control and decreases the ride comfort. In order to improve the performance of the suspension system, it is necessary to discuss the outputs of the levitation module excited by track periodical irregularities. To explore this problem, a levitation module model contains two suspension units is derived firstly. This model can represent the coupling condition of the suspension units in the levitation module. And then, for further research, based on the levitation module model, a PD controller is designed to keep the levitation module stable. Secondly, by taking the track periodical irregularity as the disturbance input, the outputs characteristic difference of the two units in a levitation module are investigated and several conclusions are obtained. The conclusions provide several advices for the suspension controller design in the next stage. At last, field experiments are carried out and the results illustrating the correctness of conclusions are provided and analyzed.

Polychlorinated biphenyls (PCBs) are required to be controlled by the Stockholm Convention due to their significant potential impacts to the environment and human health. Parties to the Stockholm Convention are obliged to prohibit the production of PCBs totally, eliminate equipment and oils containing PCBs from use by 2025 and bring these under environmentally sound waste management by 2028. Pollution to the environment and harm to the human health from PCBs in developing countries is serious in Asia-Pacific Region. This paper first summarizes the information of basic national status of PCBs in countries through analysis of submitted National Implementation Plans (NIPs), including production, import, inventory, disposal of PCBs. Then investigate and assesses the progress of PCBs management and elimination in Asia-Pacific countries on the base of PCBs projects developed by Asia-Pacific countries. Based on the obstacles and challenges analysis, the paper finally makes some suggestions on PCBs management and elimination at the regional level, including cooperation among regional countries, information exchange and experiences share, and.

Connector-based component assembly is an effective way to reuse components. Combing with the status of Component model and component assembly method based connector, this paper puts forward a model named KRC (Knowledge Reasoning Connector) which based on knowledge reasoning. This connector module using the virtual component modes to encapsulate internal controls in a component, with this mechanism can let the connector with Control, coordinate interaction between components in the active way. The method of KRC with Frame work 4.0 platform has been well applied to the application system GUBD(Gas Under balanced drilling), which Combined the field characteristics of the Under balanced drilling.

Fuel cell vehicle was featured with no pollution. And the energy conversion efficiency of its fuel cell was 2∼3 times higher than that of internal combustion engine. So, from the energy utilization and environment protection perspectives, fuel cell vehicle would be the ideal vehicle type in the future. The development status of fuel cell vehicles were discussed in this paper from the following aspects, the advantages, the main problems and solving ways, the world representative vehicle styles and the Chinese developing general situation etc.

A mode-locked radially polarized laser based on a ceramic Nd:YAG rod that was transversely pumped by LD bars. The maximum output power of 10.6 W was achieved with the frequency of 45 MHz, the average pulse width of 75 ps Abstract: By using a semiconductor saturable absorber mirror, we demonstrated the generation of and the beam quality of M2 = 2.11.

Charts play an important role in people’s daily production and scores exhibition with the characters of concentration, summarization, easy to analysis and comparation, help to find out the relations of all kinds of variables, besides, they are vivid and can help to make complex and abstract problems intuitive and clear. In this paper, the technologies of crystal reports and statistics analysis of data mining are applied to students’ scores analysis and evaluation on the basis of careful study about students’ information management system at home and abroad combined with specific characters of students’ scores in shenyang agricultural university, first, author designs the network analysis and assess system and displays students’ information with column charts, curve charts etc. then, study every kind of cases carefully and give reasonable views and suggestions. The practice proved that analyzing scores information with charts can provide students a platform to understand their learning intuitional and provide higher education an important method to study students’ information.

Computer system maintenance is an important component in network room management. For the complexity and different hardware configuration of University computer room, the Norton Ghost Multicast technology is used to implement the different methods and techniques under different hardware environments in this paper. especially the specific implementation steps for the establishment and running of other important links are given, and the advantages and disadvantages of each method and applicable environment are analyzed and compared, providing some convenient ways for fully tapping the potential of existing hardware resources and effectively solving some problems for the difficult system maintenance of college network computer room, in practice, it achieved good results.

On August 30, 2005, Haier was ranked 1st of China's top 10 global brands by the Financial Times. At the beginning of its foundation, Haier has managed to improve the environment by conserving energy and recycling old products. This great success results from Haier's strategy of sustainable development. The principles of the strategy are reducing both the possibility of environment pollution and the potential cost of products. Our environmentally friendly products are harmonious with the environment. It will take less time to dismantle them. Besides the principles the strategy consists of four parts, namely the environmental management system, the outside manufacturing system, environmental design and end of product life

A stable all-normal-dispersion dissipative-soliton mode-locked laser is demonstrated with a Yb3+-doped large-mode-area double-clad gain fiber, and nonlinear polarization evolution and spectral filtering composed of a grating and an aperture are exploited to produce sufficient amplitude modulation to shape pulses of this laser. The laser generates chirped pulses at a 76.6 MHz repetition rate, with an average power of 6.3 W, and a single pulse energy of 82 nJ. Pulse duration of the direct output pulse is 1.33 ps and it can be dechirped to 377 fs after externally compressed. By adjusting the grating, the central wavelength of the output pulses can also be tuned from 1025 nm to 1078 nm.