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Information technology brings motive force of modern education reform. In the context of "internet+", "cloud classroom", which integrates mobile internet, cloud computing with English courses, has become a new development trend. Based on the cloud platform of college English teaching, this study carries out the practical teaching of college English blended teaching mode in the cloud classroom. It is found that this mode has more significant effects on cultivating students' innovation ability, teamwork ability, language application ability, logical thinking ability, cultural literacy ability and so on. In the process of teaching, the awareness of teachers, the participation of students, the monitoring and evaluation system should be enhanced so as to make college English a satisfactory class for teachers and students.

Ozone pollution control has become the focus of air pollution control at this stage and even during the 14th Five Year Plan period, so it is more and more important to measure ozone concentration precisely. In this paper, based on the measurement principle of ozone concentration by ultraviolet photometry, the ozone has characteristic absorption of ultraviolet light at 254 nm wavelength, according to Lambert-Biel's law, ozone concentration can be obtained by detecting the change of UV intensity. At the same time a new design of double optical cells and dual detectors is proposed, there is no fluctuation with one source, fast response time under alternating sampling, and the built-in ozone generator is used to achieve multi-point calibration, The test was made according the standard “HJ654-2013”, the test results are far better than the requirements in the standard.

In this paper, the interface between Si nanoholes (SiNHs) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is investigated and improved to achieve high-efficiency SiNH/PEDOT:PSS hybrid solar cells. The high-density SiNHs are fabricated using short-time Ag deposition before metal-assisted chemical etching (MacEtch) method. Also, a polymer coverage method is explored to overcome the difficulty of PEDOT:PSS infiltration into SiNHs. PEDOT:PSS is mixed with co-solvent dimethylsulfoxide (DMSO) to have better polymer infiltrate into SiNHs via two-step coating process. This technique significantly improves the interface between SiNHs and PEDOT:PSS; the greatly reduced contact angle from 90° to 16° at the interface of Si and PEDOT:PSS has established this fact. In addition, the minority carrier lifetime is dramatically increased from 31.52 to 317.20 μs. The property improvement enables the SiNH/PEDOT:PSS hybrid solar cell with high Jsc of 36.80 mA cm−2, Voc of 0.524 V, FF of 66.50%, and thus PCE of 12.82%. Also, the SiNH structures have an excellent light-trapping effect, which contributes to very low average total reflectance of 3%, due to internal multiple reflections caused by subwavelength features. At an angle of incidence up to 60°, the specular reflectance maintains at as low as 1%; even at a large angle of 70°, the reflectance is still below 10%. This work provides a feasible solution process to fabricate SiNH structure and to improve organic/Si hybrid solar cells in energy and cost-effective manner.

We describe an improved synthetic wavelength method for high-precision long-distance measurement with a repetition-rate-locked femtosecond laser modulated by a fiber Mach–Zehnder electro-optic intensity modulator. Harmonics of the repetition rate accompanied with modulating sidebands will be generated via intermode beating, which will be utilized for high-precision ranging. The nonambiguity range is significantly extended with a relatively low modulation frequency, and the ambiguous distance is unwrapped by synchronous phase-shift measurements of a synthetic wavelength chain without any auxiliary measurement operation. Our experiment shows a precision better than 20 µm at 46 m range, and a high-precision translation stage is applied for preliminary test and proof-of-principle demonstration. The demonstrated system is simple and can be easily integrated, and it will find widespread applications in large-scale metrology such as large-volume manufacturing and precision formation flying.

In this study, we fabricate uniform silicon nanowire (SiNW) arrays on 6-inch mono- and multi-crystalline wafers by employing the improved solution-processed metal-assisted chemical etching (MacEtch) method. Furthermore, the improved MacEtch can be applied to various crystalline orientation wafers. The SiNW arrays are 470 nm in length with high density; they demonstrate a good optical trapping effect and reflectance well below 6% over a broad wavelength range from 300 to 1100 nm. The improved MacEtch shows no difference in reflectance for a pyramid/SiNW mono-crystalline wafer with appropriate uniformity; the average delta from the center to other positions is within 22%. The effective lifetime is lower for SiNW arrays because the higher surface state causes higher surface recombination. Finally, we make the multi-crystalline wafer into an Al-BSF solar cell device with MacEtch SiNW texture, resulting in an averaged power conversion efficiency of 17.83%, which is higher than that of standard acid-textured solar cell devices. Consequently, the improved MacEtch concept is suitable for commercial mass production in the photovoltaic industry.

TiO2 thin films deposited by magnetron sputtering possess excellent optical transmittance, high refractive index, good adhesion and chemical stability. In this manuscript, TiO2 thin films deposited by magnetron sputtering was used for the first time as an electron extraction layer in inverted polymer solar cells (IPSCs), and the effect of the TiO2 thickness on the photovoltaic performance of P3HT:PC61BM IPSCs was investigated. The highest PCE value of 3.75% was obtained when the thickness of TiO2 thin films was in the range between 42 nm and 73 nm. The absorption properties, morphology and structure of the TiO2 films were characterized by UV-Vis spectroscopy, SEM and Raman spectroscopy, and were related to the device performance of P3HT:PC61BM IPSCs. The results indicate that TiO2 films deposited by magnetron sputtering are an excellent electron extraction layer for IPSCs.

Compare with different thickness silicon thin film, 30μm, 50μm and 100μm, we demonstrate a promising way to form 30μm silicon thin film hybrid solar cells with good bending property, by using the silicon nanostructure (SiNS) to achieve low reflection and increase heterojunction areas, the device performance is enhanced to 10.15%.

The reduction of interface minority carrier recombination is regarded as a key performance indicator in improving the power conversion efficiency (PCE) of organic–inorganic hybrid solar cells. In this study, we chose two kinds of carrier-selective layers to be applied in a hybrid solar cell device. A hole selective transporting layer of N,N′-bis(3-methylphenyl)-N,N′-diphenylbenzidine (TPD) was added to the interface between Si nanohole structures and PEDOT:PSS, and the electron selective layer cesium carbonate (Cs2CO3) was added to the interface between the backside Si wafer and the rear Ti/Ag electrode. The main process used a clean and low-cost solution process, and the annealed temperature was under 140 °C. In addition, after we inserted these two carrier selective layers, the minority carrier lifetime was prolonged from 29.98 μs to 140.81 μs, indicating its significance in reducing the recombination rate. Eventually, we demonstrated that the PCE of Si/organic heterojunction solar cells can be improved to 13.23%.

To satisfy need of high resolution observation from space. This article elaborates a method of high precision spacecraft formation control based on file diffraction theory. Improving the spacecraft control accuracy to millimeter is a challenge. With the method in this article this challenge can be solved. The algorithm in this article concerning the vibration of spacecraft and based on dynamic modeling of even relative quaternion theory deduced a method of attitude and orbit integrated control. Using this control algorithm to simulation can get the result that it can make the spacecraft integrate formation control as the technical basis of space high resolution observation.

One of the outstanding challenges in phononic crystal development is the ability to achieve bandgap tunability in a low frequency range. The introduction of piezoelectric materials into phononic crystals is an attractive technique for actively controlling the bandgaps, which is reliable, economical and light in weight. Phononic crystal possesses an artificial periodic composite structure whose elastic constant, density and sound velocity change periodically. When the elastic wave passes through a phononic crystal, special dispersion curve is formed due to the interaction among periodically arranged materials. In order to study the tunability of phononic crystal bandgap, we propose a novel two-dimensional piezoelectric phononic crystal structure possessing a wider complete bandgap, which is composed of piezoelectric materials with hard coatings periodically connected by four thin bars. The dispersion relation, transmission spectrum and displacement field are studied by using the finite element method in combination with the Bloch theorem. Numerical results show that the frequency of the first complete bandgap of the new designed phononic crystal slab is lower and the band width is enlarged by a factor of 5 compared with the band width of the traditional binary phononic crystal. Instead of changing the geometry or orientation of the phononic crystal units or inclusions, electrical boundary conditions are used to actively control the frequency bandgap. The boundary condition for electrical open circuit and short circuit are considered in this paper. With different electrical boundary conditions imposed on the surfaces of the piezoelectric inclusions, multiple complete bandgaps can be controlled actively, which means that the new designed phononic crystal structure can adapt to the vibration and noise reduction requirements under different vibration environments. The effect of piezoelectric effect on the band structure is investigated as well. The piezoelectric effect has a great influence on the band structure, with the increase of the piezoelectric constant, a part of bands move to high-frequency and the other part of the bands are kept at the original position, which means that the piezoelectric effect is of benefit to the opening of the complete bandgap. Furthermore, according to the tunability of the bandgap, the switchable piezoelectric phononic crystal slab waveguide is analyzed. Calculation shows that the electrical boundary defects can result in defect bands existing in the complete band gap, and the elastic wave energy flows can be limited by changing the applied electrical boundary conditions. This investigation is conducive to controlling the bandgaps and also reveals potential applications in designing the sensing system and different piezoelectric devices.

Nanostructured silicon hybrid solar cells are promising candidates for a new generation photovoltaics because of their light-trapping abilities and solution processes. However, the performance of hybrid organic/Si nanostructure solar cells is hindered because of carrier recombination at surface and poor coverage of organic material poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PSS) on nanostructures. Here we demonstrate low-pressure-assisted coating method ofPSS on surface-modified silicon nanotips with broadband light-trapping characteristics to improve interface property and to achieve high-efficiency hybrid solar cells through a solution process. The approach enhances the effective minority-carrier lifetime and the coverage ofPSS on the surface of nanostructures. Hybrid solar cells fabricated with surface-modified nanotips exhibit a high fill factor of 70.94%, short-circuit current density of 35.36 mA/cm(2), open-circuit voltage of 0.528 V, and power conversion efficiency of 13.36%. The high efficiency and the high fill factor are achieved because of conformal coating ofPSS via a low-pressure-assisted coating process, excellent light harvesting without sacrificing the minority-carrier lifetime, and efficient charge separation/collection of photogenerated carriers.

For the spacecraft which has great flexibility and strong coupling has the large ground measurements error of flexible parameters and the high-precision in orbit control difficulties. Based on piezoelectric ceramic sensor and actuator we design the active vibration suppression program which obtains the dynamics model of spacecraft that has great flexibility through parameter identification of high-precision quality characteristics. By the analysis of the vibration characteristics the program can figure the characteristic points that can accurately reflect the vibration feature of spacecraft or restrain that. Then we can select the points which represent the flexible vibration feature of spacecraft. Through combining the vibration message obtained through piezoelectric sensors the attitude massage and parameters of control mechanism we can figure the mechanical parameter of flexible vibration and construct dynamic model. We design the piezoelectric ceramic actuators and reaction wheels as executive mechanism and fix multiple piezoelectric ceramic actuators on the vibration suppression points. The multiple piezoelectric ceramic actuators charge for the vibration suppression and the reaction wheels charge for the attitude control of spacecraft. Linear quadratic control method is used. We do the system verification on the air flotation platform. The result shows that the program can suppress the active vibration and achieve the high-precision control of great flexibility satellite.

The complex network theory is applied to manufacturing, manufacturing of complex networks have been proposed fault model construction methods. According to the four different manufacturing network, based on the performance of a large number of experimental data of successive failure model is analyzed.

In this work, a simple method of solution process to fabricate high density Silicon nanohole (SiNH) arrays on n-type wafer is experimented. SiNHs exhibit very low reflectance from range of wavelength 300 to 1100 nm irrespective of the angle of incidence, better than Si nanowires. The SiNH arrays have a strong light trapping effect between the nanostructures causes high absorption. We experimentally demonstrate high-efficiency organic-inorganic hybrid solar cells, Si/PEDOT:PSS with silicon nanoholes. Such Si/PEDOT:PSS hybrid solar cells exhibit high Jsc of 36.80 mA/cm2, Voc of 0.52V, FF of 66.50%, and thus power conversion efficiency (PCE) of 12.72%. SiNH arrays produce a large surface-area-to-volume ratio, hence allowing efficient light harvesting and charge collection via the formation of a core-sheath p-n junction.

Information and computer science is mathematics, computer as a tool of discipline with a wide application prospect. The training of professionals not only meet the professional orientation, but also reflects a certain degree of innovation. So the development of creative talents in this professional program is necessary.

On the complex networks formed by the Internet of things of network nodes, information transmission between network nodes is the subject of things in a new research direction. This paper focuses on the complex network of information dissemination mechanism, through the use of the Internet routing table information simulation model of the internet of things network topology. By analysis transmission of the virus according to biological mechanisms and transmission dynamics of small world network, it's indicates that information dissemination in accordance with the node degree distribution is optimal efficiency.

The "brain drain" of nonprofit organizations ( NPOs) has become one of the bottlenecks hindering its development. The paper starts from the relationship between internal service quality and staff satisfaction of NPOs, analyzing how to attract and retain talents by raising staff satisfaction. By factor analysis and linear regression analysis, the paper concludes that the five dimensions of "value formation", "policy procedure", "seniors' support", "team communication" , and "work environment" of NPOs' internal quality are positively related with the staff satisfaction, while of these five dimensions, the following three of "value formation", "team communication " and "work environment" can obviously predict the staff satisfaction. The conclusion reached in the paper can be taken as theoretical and practical guidance to the internal staff management of NPOs.

This paper designs the H ∞ state feedback controller of the low-orbit satellite to achieve the high precision attitude control. Based on the analysis of the system uncertainty and environment disturbance of the low-orbit satellite, H ∞ method is adopted and the LMI arithmetic is used to make the computation easier. The results of the system simulation prove that the algorithm is useful and can make the attitude control system achieve the high precision requirements.

Continuous long-term measurements of carbon fluxes have been obtained by improved technology at the ecosystem scale and under natural conditions. Nevertheless, these are still point measurements with limited geographic coverage Quantitative extrapolations and scaling-up of tower station measurements are now urgently needed for carbon cycle research. This paper attempts to solve this problem by combining the technologies of CO2 flux measurements, mathematic modeling, Geographic Information System (GIS) and Remote Sensing (RS). It is well known that the light-response function allows partitioning net ecosystem exchange (NEE) into gross primary production (GPP) and total ecosystem respiration (Re). The GPP and Re can be estimated from continuous CO2 flux measurements using non-linear identification of the non-rectangular hyperbolic model of ecosystem-scale, light response curves. Patterns of the relationships of GPP and Re with the Normalized Difference Vegetation Index (NDVI), and other factors, indicate possibilities to establish multivariate functions, allowing scaling-up of local fluxes to larger areas with GIS technology, temporal NDVI inversed from RS images, and other tools. Our study is based on continuous CO2 flux data, which were measured at the Haibei Alpine Meadow Ecosystem Research Station (Haibei Research Station) on the Qinghai-Tibet Plateau, the Chinese Academy of Science. Using the above methods, we achieved good flux-NDVI relationships at the site and applied these relationships in the scaling-up of site-specific CO2 flux measurements to regional levels. Consequently the annual spatial and temporal variation of CO2 flux was obtained for this plateau and eco-region. Characterizing spatial and temporal dynamics of CO2 flux will facilitate investigations of the carbon source or sink status of grassland ecosystems on the plateau.

Monitoring moving objects is one of the key application domains for sensor networks. In the absence of cooperative objects and devices attached to these objects, target tracking algorithms have to be used for monitoring. In this paper, we present that many of the applications of moving object monitoring systems could be addressed with low-frequency snapshot-based queries. With the realization of this query type, we show that existing target tracking algorithms may not be the least expensive solutions. We introduce an approach that uses two alternating strategies. We maintain a cheap low-quality knowledge of moving objects' location between snapshots and trigger expensive sensor readings only when a snapshot period has elapsed. With extensive experiments we show that our approach is significantly more energy efficient than established methods. It is also more effective than existing data-and-query centric in-network query processing schemes as it can maintain object identities between snapshots.

In wireless communication environment, the time-varying channel and angular spreads caused by multipath fading and the mobility of mobile stations (MS) degrade the performance of the conventional direction-of arrival (DOA) tracking algorithms. On the other hand, although the DOA estimation methods based on the maximum likelihood (MI) principle have higher resolution than the beamforming and the subspace based methods, prohibitively heavy computation limits their practical applications. In this paper, we first propose a new suboptimal DOA estimation algorithm that combines the advantages of the lower complexity of subspace algorithm and the high accuracy of MI based algorithms, and then propose a Kalman filtering based tracking algorithm to model the dynamic property of directional changes for mobile terminals in such a way that the association between the estimates made at different time points is maintained. At each stage during tracking process, the current suboptimal estimates of DOA are treated as measurements, predicted and updated via a Kalman state equation, hence adaptive tracking of moving MS can be carried out without the need to perform unduly heavy computations. Computer simulation results show that this proposed algorithm has better performance of DOA estimation and tracking of MS than the conventional MI or subspace based algorithms in terms of accuracy and robustness.