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Although various terahertz (THz) functional devices based on artificial materials have been widely proposed, their performance is still unsatisfactory due to the limitation of the involved guided wave modes. The introduction of defects can result in a strong localization effect, which has been found in applications of improving device performance. Due to Bragg resonances, the localization is usually symmetrical about the center of defects. Here, based on multiple mode resonances, we demonstrate an antisymmetric localization of THz waves in a periodic parallel plate waveguide with non-Bragg nature resonances. Unexpectedly, such resonances can produce two extremely narrow transmissions with a transmittance close to 1, and the narrowest linewidth can reach 2 MHz and the Q-factor is close to 7.44 × 105, which would be good candidates for THz filtering and sensing. Referring to the field distributions, we employ the mathematical operation symbols of the equal sign ‘=’ and the multiplication sign ‘×’ to intuitively mark these two antisymmetric localizations with different characteristics. The dispersion curves and mode analysis reveal that the observed antisymmetric localizations caused by non-Bragg resonances are induced by the first- and second-order transverse modes. Furthermore, the frequency of antisymmetric localizations can be manipulated by changing the geometry of defects. Our findings on extremely narrow transmission peaks and antisymmetric localizations pave a way for creating high performance THz functional devices, such as switches, filters, and sensors.

Ice problem widely exists in the north rivers, especially the ice disaster of the water elevation rise triggered by local ice jam in melting period caused by flowing ice. Therefore, it is of great significance to study the formation and influence of ice jam during the melting period. In this paper, the characteristics of ice flow in Yumenkou reach of the Middle Yellow River during the melting period is studied by laboratory physical model tests using paraffin as model ice. The results showed that: The formation of ice jam is controlled by flow rate and ice density during the melting period. When the flow rate is small and the density of flowing ice is high, there are enough ice cubes in a certain space who have enough time to combine with each other to form an ice jam. An ice jam is made up of at least two ice cubes stacked on top of each other vertically whose backwater influence is at least greater than the maximum height of one ice cube. An ice jam is more likely to form in the wider reaches of the river. The reason for that is, when the flow ice density reaches a certain level, the flow velocity is reduced more due to the wider river width, and the ice cubes are more likely to collide, squeeze and combine with each other, which are not easily transported by water with low flow intensity.

The integrated test of weapons and equipment is an urgent need for the development of weapons and equipment under the contemporary information conditions, because it can reduce the resource requirements, test cost and risk, as well as improve the test efficiency and the degree of confidence. This paper based on the objective requirements of integrated evaluation of information system equipment test, aims at performance test for information system equipment. For the same equipment testing, test means to analysis the factors that affect performance. The implementation is based on prior knowledge and expert experience response parameters, including regression model building, and the credibility of the weighted multi-source data fusion evaluation method research. It provides technical and theoretical support for the integrated test evaluation of information system equipment multi-source test.

The employment situation in civil aviation has become more severe this year due to the adverse effects of the COVID-19 epidemic. The online teaching of employment guidance courses can promote high-quality employment for graduates, but also poses new challenges for teachers and students. For college students enrolled in 2018 majoring in civil aviation, the teachers in the Civil Aviation Management Institute of China accomplished the employment guidance course, adopting a teaching method combining online teaching with offline guidance, and applying the Deming cycle to continuously improve the course quality. To facilitate better employment of civil aviation graduates under the epidemic, this paper suggests that it is necessary to establish an employment guidance and service system, improve the comprehensive quality of graduates, promote cooperation and mutual assistance between schools and employers, and guide graduates to start their businesses or further study rationally.

Big Data” has existed for some time in various industries such as military, finance and communication, but has attracted attention because of the development of Internet and information industry in recent years. With the extensive development of big data applications has increased the demand for talents, and the number of big data training courses has increased. Due to the unique content of big data teaching, it can be appropriate to teach big data through network teaching platform, so this paper explores the application of big data teaching based on network teaching platform for big data teaching.

In the interconnected power systems with VSC-HVDC (Voltage Source Converter-High Voltage Direct Current) transmission links, the failures of VSC-HVDC system can cause large power imbalance for both sending-end and receiving-end power systems. In this paper, the reliability model of the VSC-HVDC system is developed based on series-parallel structure recognition. The frequency dynamics of the power systems are characterized considering the frequency regulation of the power systems in response to the power imbalance arise from the component failures. Moreover, the Monte Carlo simulation method is applied to analyze the frequency dynamics in different contingencies. The indices measuring the frequency stability and the reliability of the interconnected power systems are introduced.

This paper focuses on the general knowledge and basic use of timber based on the case study in United Kingdom. It is narrated from the whole life cycle of wood, from its cradle to death, including its growth, application, degradation, decay detection repairing methods and techniques, etc. The purpose of this paper is to provide guidance on the wider application of wood in architecture, especially on the conservation of historic buildings.

It is of great reference for the studying of the successful implementation of the responsible planners system and examples. The role of the responsible planner as a bridge, providing local services, deepening the understanding of the territory and mutual trust with the territorial units through the model projects, protecting the interests of the responsible planner by multi platforms, etc., provided useful reference to the establishment and improvement of Beijing responsible planners system, including the team selection, work contents and work methods, as well as the working mechanism, security system, evaluation mechanism and other aspects.

Through the investigation of some public rental housing projects in Beijing, the family structure, rent, income and satisfaction of the public rental housing households can be revealed. Through the statistical analysis, we found the following problems: some public rental housing family structure does not match with the type of occupancy; the rental income ratio of part of the public rental housing is unreasonable; some of the households has low satisfaction; the income of part of the public rental housing exceeds the prescribed upper limit. In view of the above problems, this paper proposes solutions: strengthen the planning and design of public rental housing; improve the rent subsidy mode of public rental housing; strengthen the construction of supporting facilities for public rental housing; promote the relevant legislative work of public rental housing.

In 2019, Beijing issued the Beijing Implementation Measures for the Responsible Planners System. The responsible planners then became one of fundamental strength in the refined urban governance chain. This paper discusses the importance of corresponding territory investigation to the work of responsible planners from content and time sequence perspective. This paper also points out the relationship between “urban physical examination” and corresponding territory investigation of responsible planners in the era of big data, and offers suggestions for the promotion of future work.

To reveal the gas-liquid two-phase flow characteristics in water supply pipeline due to the rugged terrain, flow pattern, pressure, velocity, turbulent kinetic energy and turbulent energy dissipation rate of 6 key sections and 4 profiles were simulated and analysed on the conditions of with and without exhaust valve. The results showed that water cannot flow smoothly without exhaust valves at sections 1-1, 2-2 and 3-3, while that flows smoothly at sections 4-4, 5-5 and 6-6. For sections 1-1, 2-2 and 3-3, water can only cover less than 50% of the pipeline cross section when the exhaust valves were not set, and various backflow zones can be observed in these sections, which can increase the resistance of the water flow. The turbulent kinetic energy of the cross sections 1-1, 2-2 and 3-3 were 0.87, 1.02 and 0.09 m2/s2, which can decrease to 0.0018, 0.0017 and 0.0017 m2/s2, respectively, after the exhaust valves were set. Meanwhile, the pressure in different cross sections reduced by 1 to 10 kPa and the streamline were nearly uniform and straight for the main flow in the pipe with the exhaust valves. The reverse vortex disappeared and the velocity distribution of the main flow was more uniform in these sections.

the introduction of power to gas P2G (power to gas) equipment inside the micro grid strengthens the coupling between the power and natural gas network, reducing the phenomenon of wind and light abandoning, but also makes the renewable energy during the optimal scheduling of energy conversion, reducing energy efficiency, resulting in energy consumption. At the same time, with the aggregation of more and more microgrids in a certain region, a multi-microgrid system is formed, which has power interaction between microgrids. In this context, CVaR is introduced into the objective function of economic dispatching, and an optimal scheduling model considering the internal energy repeated conversion and power interaction between microgrids is established. This model takes into account the influence on the output of each equipment, and the optimal operation plan and optimal operating cost of the system are obtained. Finally, an example is given to verify the model, and the results show that the proposed optimal scheduling model can reduce the operating cost of the system, improve the energy efficiency and realize the energy optimization management of the whole system under the condition of improving the consumption of renewable energy.

The high-temperature deformation behavior of the SA508 Gr.3Cl.1 steel was investigated by the uniaxial isothermal compression tests at the deformation temperature from 1223 K to 1473 K and strain rate from 0.001s−1 to 1 s−1, which were carried out using Gleeble-1500 thermo-mechanical simulator. Based on the experimental data, the material parameters and active energy of hot deformation were determined according to the regression analysis method. The critical strain of dynamic recrystallization (DRX) was confirmed by simplified P-J method. Furthermore, the constitutive model for work hardening-dynamic recovery (WH-DRV) stage and DRX stage was established based on dislocation density theory and the kinetics of DRX. Finally, the flow stress calculated using the established model and experiment data was compared and the results showed that it is enough accurate to predict the flow stress during hot deformation for SA508 Gr.3Cl.1. Thus, the model will be beneficial for the accuracy of simulation by Finite Element Method (FEM) method.

A stable and accurate pointing, acquisition system is an important part of initially building intersatellite optical communication links. Satellite platform vibration can cause the system instability and reduce the system precision in building and maintenance of a satellite optical communication system. In this paper, vibration influence is consciously discussed by acquisition time for intersatellite optical communications. Analytical expression of acquisition possibility is derived, taking the scan parameters and platform vibration into account, and vibration influence on the multi-scan acquisition time is also presented. The theoretical result calculated by the proposed analytical expression is approximate to the result by the Monte Carlo simulation.

Accurate prediction for the binding energies of host-guest complexes is important in the field of supramolecular chemistry. In this article, we have implemented an improved generalized energy-based fragmentation (GEBF) approach for computing the binding energies of supramolecular complexes. In this approach, an new scheme is proposed to generate primitive GEBF subsystems with reasonable size. With this scheme, those subsystems in the complex and the corresponding host molecule are very similar (the guest does not exist in any subsystem of host). Our results for ten supramolecular complexes show that the improved GEBF approach could accurately reproduce the conventional density functional theory (DFT) binding energies in those complexes. The GEBF binding energy errors relative to the corresponding conventional values are usually less than 1 kcal/mol. Furthermore, for each pair of complexes with the same or similar hosts, the GEBF relative binding energy difference between the two complexes with different guests is even below 1 kJ/mol. In addition, the GEBF approach could predict the second-order Moller-Plesset perturbational theory (MP2) energy of a complex with 3382 basis functions within only 3.3 hours by massive parallelization using 312 processors on 13 computer nodes. Therefore, the improved GEBF approach could be a practical tool for predicting the binding energies or relative binding energies of supramolecular complexes.

Exfoliation of two-dimensional (2D) materials is an issue of concern among scientific researchers. This is because many solvents such as N, N-dimethylformamide and N-methyl-2-pyrrolidone that are capable of better dispersion of 2D materials are relatively toxic and nonvolatile. This work focused on the reasonable design and mixture of two or three less toxic and volatile solvents based on Hansen solubility parameters theory to demonstrate the excellent exfoliation of 2D materials particularly reduced graphene oxide (rGO) and black phosphorus (BP). Polyvinylpyrrolidone (PVP) was introduced as a surfactant to functionalize rGO to help improve its dispersion. Results showed that PVP could effectively functionalize graphene. Few layers of rGO and BP were facilely achieved with 2-3 nm thickness from the use of the designed solvent mixtures, indicating the accomplishment of solvent mixtures in exfoliation/dispersion roles instead of the use of other toxic and nonvolatile solvents.

This paper mainly takes Cangzhou City as an example to study spatial distribution of influence factors of residential land price, in order to deeply understand the driving factors of the spatial heterogeneity of residential land price in Cangzhou City. Based on the GWR model, the analysis of the influence factors of residential land price shows that the urban center has a significant positive impact on land prices, that is, the closer to the city center, the higher the land price is. The main roads, schools, and parks have different positive impacts on residential land prices, and there are large spatial differences in the degree of influence of various factors. The canal has a negative impact on residential land prices, that is, the closer to the canal, the lower the land price, mainly due to the existence of villages in city on both sides of the canal, which has a certain inhibitory effect on land prices. The impact of hospitals on residential land prices is not regular in spatial distribution.

Through the multi-period, multi-objective and multi-level investigation and analysis of the existing national railway hubs in Beijing, the main problems in the current operation is that the urban space connection and various types of traffic connections. The reason is that the railway hub transportation station should focus on development positioning, site selection layout, traffic matching and predictive design in the planning and site selection design process. The key points can be used as a useful reference in the design of the similar ones.

Based on the clear positioning of Beijing core areas in the new urban planning of Beijing, Dongcheng District and Xicheng District have carried out a series of urban renewal work of “Environmental Remediation of hundreds of streets and allies” and “Rearrangement Planning of Blocks”. Both districts explored and established the responsibility planner system in 2017, aiming to achieve refined construction and management in the process of organic renewal, and ensure the implementation of the plan and public participation. This paper, combined with the visiting and investigational results of the urban renewal project in Beijing core areas, sorts out the duties and roles of the responsibility planners in each step, explores the establishment and promotion of the responsibility planner system, analyzes the optimization space of current system and proposes several advices on the follow-up system.

Carbon nanotubes (CNTs) have been involved into the counter electrodes of dye-sensitized solar cells (DSSCs) to utilize its low cost and considerable electrical conductivity. However, the dispersion of CNTs needs to be improved because the aggregate of CNTs harms the performance of counter electrodes on DSSCs. In this work, aligned carbon nanotubes (ACNTs) were functionalized by adding poly (3,4-ethylenedioxythiophene)/poly(styrenesulfonic acid) (PEDOT:PSS), polyethylene glycol octylphenol ether (Triton X-100) and the blends of these two substances, respectively. The analysis results from Fourier transform infrared spectrometer (FTIR), x-ray diffraction (XRD), Raman, Thermogravimetric analysis (TGA) thermograph and x-ray photoelectron spectroscopy (XPS) analysis indicated that ACNTs were functionalized effectively. Then the ACNTs, Triton X-100/ACNTs, PEDOT: PSS/ACNTs and Triton X-100/PEDOT: PSS/ACNTs were employed as the counter electrode of DSSCs. The electrochemical activity of these counter electrodes and the photovoltaic properties of the DSSCs were detected. DSSCs with PEDOT: PSS/ACNTs counter electrode showed the best photoelectric conversion efficiency (PCE) of 3.85%, it is due to the PEDOT: PSS/ACNTs possessed remarkable electrochemical property and low value of Rct.

Three-dimensional (3D) SnO hierarchical architectures were synthesized via a one-step dissolution–precipitation route under room temperature using SnCl2 2H2O and Na2CO3 as the initial reagents. The morphology and size of the prepared SnO structures could be easily tailored by alternating the solvent from deionized water with absolute ethanol. The SEM observation showed that the prepared 3D SnO hierarchical architectures consisted of nanosheets. The size of the SnO hierarchical architectures could be effectively reduced from 4–10 μm to 1–2 μm when the solvent was changed from water to ethanol while the thickness of the assembling nanosheets was reduced from 200–500 nm to 20–30 nm at the same time. The possible formation mechanism of the 3D SnO hierarchical architectures is proposed in this paper. The photodegradation of methylene blue revealed that the SnO hierarchical structures prepared using ethanol as the solvent exhibit much better photocatalytic activity due to its smaller particle size, larger specific surface area, and appropriate band structure as well.

Radiation effects on semiconductor nanowires (NWs) have attracted the attention of the research community due to their potential applications in space and atomic fields. The effective implementation of NW devices in a radiation environment is a matter of concern. Here, the photoluminescence (PL) and time-resolved PL (TRPL) measurements were performed on both GaAs and InP NWs at room temperature before and after 1 MeV H+ irradiation with fluences ranging from 1 × 1011 to 5 × 1013 p cm-2. It is found that the degradation of lifetime is size-dependent, and typically the minority carrier lifetime damage coefficient is closely correlated with the material and NW diameter. Compared to GaAs and InP bulk material counterparts, the lifetime damage coefficient of NWs decreases by a factor of about one order of magnitude. After irradiation, GaAs NWs with a smaller diameter show a much lower lifetime damage coefficient while InP NWs show an increase in carrier radiative lifetime. The increased size-dependent radiation hardness is mainly attributed to the defect sink effect and/or the improvement of a room temperature dynamic annealing mechanism of the NWs. The InP NWs also showed higher radiation tolerance than GaAs NWs.

In order to get knowledge of the standard of water utilization of the Silk Road Economic Belt from international point of view, the paper analyzes the annual variation of water resources utilization in the Silk Road Economic Belt, and compares with other typical countries. The study shows that Water resources utilization efficiency has been greatly improved in recent 20 years and the water consumption per USD 10000 of GDP has been declined 87.97%. the improvement of industrial water consumption efficiency is the key driving factors for substantial decrease in water consumption.The comparison of water utilization and human development shows that the higher HDI the country is, the more efficient water utilization the country has. water consumption per USD 10000 of GDP in country with HDI>0.9 is 194m³, being 8.5% of that in country with HDI from 0.5 to 0.6. On the premise of maintaining the stable economic and social development of the Silk Road Economic Belt, the realization of the control target of total water consumption must depend on the strict control over the disorderly expansion of irrigated area, the change in the mode of economic growth, the implementation of the development strategy for new industrialization and urbanization, vigorous development of the processing industry with low water consumption as well as the high-tech and high value-added industry. Only in this way, the control target of total water consumption can be realized in the process of completing the industrialization task.

We found that 90° domain walls are absorptive to oxygen vacancies and the absorbing degree was related with the morphology of 90° domain walls: curved 90° domain walls are more absorptive to oxygen vacancies compared with straight 90° domain walls. Therefore, in ferroelectric materials with curved 90° domain walls, the density of oxygen vacancies diffusing to and subsequently pinning the 180° domain walls is greatly suppressed, resulting in their excellent fatigue resistance.

Social interaction between individuals constantly affects the development of their personal opinions. Previous models such as the Deffuant model and the Hegselmann-Krause (HK) model have assumed that individuals only update their opinions after interacting with neighbors whose opinions are similar to their own. However, people are capable of communicating widely with all of their neighbors to gather their ideas and opinions, even if they encounter a number of opposing attitudes. We propose a model in which agents listen to the opinions of all their neighbors. Continuous opinion dynamics are investigated in activity-driven networks with a tolerance threshold. We study how the initial opinion distribution, tolerance threshold, opinion-updating speed, and activity rate affect the evolution of opinion. We find that when the initial fraction of positive opinion is small, all opinions become negative by the end of the simulation. As the initial fraction of positive opinions rises above a certain value —about 0.45— the final fraction of positive opinions sharply increases and eventually equals 1. Increased tolerance threshold δ is found to lead to a more varied final opinion distribution. We also find that if the negative opinion has an initial advantage, the final fraction of negative opinion increases and reaches its peak as the updating speed λ approaches 0.5. Finally we show that the lower the activity rate of individuals, the greater the fluctuation range of their opinions.

With selective laser melting the potential to manufacture a wide variety of geometries from different materials has presented itself. Interest in this technology keeps growing every year, and with that growth a deeper understanding of the process and resulting materials is urgently needed. In this paper we present a short overview of the structural elements that appear during selective laser melting, and explain how to tailor them to achieve specific structures and material properties. Melt-pools, texture and grains, subgrain cells, and inclusions are the elements discussed herein, and tailoring of these elements can have effects on density, and corrosion resistance, as well as mechanical properties in general.

Thermal nanoimprinting technology was employed to fabricate 3D periodic nanocone ZnO films with different height/pitch values for photodetectors to optimize their light capturing property. The photocurrents of patterned film photodetectors increase with the height/pitch values. The patterned ZnO-Au hybrid film further boosts the ultraviolet (UV) response. Due to the co-contribution of the light trapping of 3D periodic structures and the driving force of the Schottky barrier in the Au/ZnO interface, the patterned ZnO-Au hybrid films with height/pitch of 40 nm/866 nm exhibit the best UV photoresponse (I on/I off = 779.927), which is 3.8 times higher than its film counterpart (I on/I off = 164.1).

Graphene-based polymer composite films have wide-ranging potential applications, such as in sensors, electromagnetic shielding, absorbing materials, corrosion resistance and so on. In addition, the practical applications of graphene-based polymer composite films are closely related to their mechanical properties. However, the mechanical properties of graphene-based polymer composite films are difficult to characterize with tensile tests. In this paper, the bugle test was used to investigate the mechanical properties of graphene-based polymer composite films. The experimental results show that the Young's modulus of polymer composite films increases non-linearly with an increase in the doping content of graphene, and viscoelastic deformation is induced under cyclic loading conditions. Moreover, in order to describe their mechanical behavior, an 'Arruda–Boyce' finite-strain constitutive model (modified BPA model), based on the strain amplification hypothesis, and a traditional 'Arruda–Boyce' model was proposed, which incorporated many of the features of previous theories. The numerical treatment of the modified BPA model associated with finite element analysis is also discussed. This new model is shown to be able to predict the experimentally observed mechanical behavior of graphene based polymer composite films measured by the bugle test effectively.

An aluminum grating with period of 152 nm is designed and manufactured based on rigorous coupled wave analysis. Its transmissions of TM and TE waves are measured at 532 nm, 632.8 nm and 810 nm, respectively. From the agreement between the experimental results and simulations, a grating thickness of 80 ± 5 nm can be determined. The analysis of and experiments on the grating temperature dependence reveal its thermal stability in ambient conditions.

The electro-optical crystals exhibit thermally insensitive optic propagation orientations, which satisfy the demand of outdoor industry and military applications. With the aid of wave coupling theory, the temperature stability of the LiNbO3 modulator under dynamic electric field is studied and dynamic thermal insensitive (TI) propagating orientation is sought. It is found that a number of propagation orientations have a dramatically different temperature property when the electric field is varied significantly. The temperature drift of light intensity in specific static TI orientation is raise by 3 orders of magnitude. While for dynamic TI orientation, the effect of the electric field is very limited and the temperature drift of modulated intensity can be controlled below 0.3%. The change of electric field orientation does not influence the temperature characteristics of dynamic TI orientation. An effective method is developed to find the thermally insensitive orientations. And the method is suitable for any type of electro-optic crystal with an applied electric field along arbitrary directions.

A new light-trapping-structure combined of diffraction grating and rear-located bilayer silver nanoparticles for thin-film silicon solar cells are theoretically investigated. By analyzing the absorption spectra and electric field intensity profiles, we find that the grating suppresses the reflection and results in the incident light angular redistribution, and that the rear-located bilayer nanoparticles fold light into the active layer. Furthermore, the grating and metal NPs are optimized and a short-circuit current density as high as 29.7 mA/cm2 is obtained within a 1-µm-thick cell. In addition this design is applicable to silicon solar cells of various thicknesses.

The enhancement and tunable color emissions from codoped lanthanide ions of Er3+/Tm3+/Yb3+ have been studied extensively in recent decades. In this paper, we present a new scheme for quantum coherent control of two-photon absorption (TPA) and color emission in codoped lanthanide ions of Er3+/Tm3+/Yb3+ by properly phase shaping two infrared ultrashort laser beams at central frequencies of 10 650 cm−1 and 7650 cm−1, respectively. Compared with the results irradiated by transform-limited pulses, the TPA probabilities of the blue, green and red emissions are independently controlled in the ranges 0–13.3, 0–14.5 and 0–1.0, respectively. The effects of the energy states of lanthanide ions and the laser spectral bandwidths on the coherent features are also discussed. The TPA probabilities for the blue and green emissions increase with the laser spectral bandwidths and decrease with the energy bandwidths of the final level states. As the intermediate energy level shifts in the range 10 100–10 500 cm−1, the TPA probabilities for the blue and green emissions change in the ranges 7–15 and 8–17, respectively.

The polymerization and feature size in micro/nanofabrication are usually controlled by changing the femtosecond laser pulse energy and irradiation pulse number. In this paper, we present the coherent control of two-photon absorption (TPA) and polymerization in a polymer with a isopropyl thioxanthone (ITX) photoinitiator by modulating the phase of 800 nm femtosecond laser pulses. We demonstrate experimentally and theoretically that the TPA probability and polymerization can be efficiently controlled by shaped ultrashort laser pulses. By using this method, the volume of a fabricated microrod decreases to 1/125 of that induced by Fourier transform limit laser pulses, and it is less than 1/25 of the diffraction limit.