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The study of chaotic attractors has been a hot issue in complex science research in recent years. However, most of the current research has focused on low-dimensional dissipative systems. High-dimensional conservative systems have both conservative and hyperchaotic properties, the phase space is integer dimensional and does not have attractors, and the trajectories expand in multiple directions, thus having higher complexity and spatial ergodicity. In addition, the high dimensional conservative system with wide parameter range not only has better dynamic characteristics, but also has a good application prospect in the field of information security. In this paper, a novel seven-dimensional Hamiltonian conservative hyperchaotic system (7D-HCHCS) is constructed. The dynamical properties of this system are described by analyzing the rate of change of phase space volume, phase trajectory diagram, Poincaré map, Lyapunov exponential spectrum (LEs), bifurcation diagram, equilibrium point, and system complexity. A new pseudo-random number generator (PRNG) is designed on this basis, and the key stream generated by this PRNG passes the NIST test. Besides, the phase diagrams and Poincaré map under a wide range of parameters are compared. The results show that the proposed system satisfies the Hamilton energy conservation and can generate hyperchaotic flow. It also has good pseudorandom characteristics, ergodicity under a large range of control parameters, which also has good prospects in the field of information security.

With the increasing proportion of new energy into the power grid, environmental management and energy supply issues are becoming more and more prominent. In the current severe environment and energy situation, high-quality development of new energy and rational allocation of energy has become an urgent problem to be solved. In China, some regions are rich in clean energy resources, such as wind and solar energy. New Energy can not be absorbed on the spot. In view of this, on the premise of satisfying the security and stability of the power grid and the efficient operation of the transmission channel, the wind-fire combined transmission mode is proposed, the interests of all parties involved in the cross-provincial transaction are analyzed, and the inter-provincial transmission model is constructed, effectively relieves the pressure of the abandoned wind power and the abandoned nest power.

Thermoelectric devices (TEDs), including thermoelectric generators (TEGs) and thermoelectric coolers (TECs) based on the Seebeck and Peltier effects, respectively, are capable of converting heat directly into electricity and vice versa. Tough suffering from low energy conversion efficiency and relatively high capital cost, TEDs have found niche applications, such as the remote power source for spacecraft, solid-state refrigerators, waste heat recycling, and so on. In particular, on-chip integrable micro thermoelectric devices (μ-TEDs), which can realize local thermal management, on-site temperature sensing, and energy harvesting under minor temperature gradient, could play an important role in biological sensing and cell cultivation, self-powered Internet of Things (IoT), and wearable electronics. In this review, starting from the basic principles of thermoelectric devices, we summarize the most critical parameters for μ-TEDs, design guidelines, and most recent advances in the fabrication process. In addition, some innovative applications of μ-TEDs, such as in combination with microfluidics and photonics, are demonstrated in detail.

Metallic high aspect ratio (HAR) nano-architectures provide new opportunities for a series of plasmonic devices due to their additional controllable degrees in height space compared to 2D patterns, but there is no efficient way that suitable for the rapid fabrication of large area HAR structures limited by the processing ability of traditional methods. Here in this work, we have developed a templated electrochemical deposition (ECD) method to fabricate various HAR metallic nano-structures for diversified plasmonic devices. The templated ECD method is based on the ECD filling of the nanopores that are fabricated by electron beam lithography. With this templated ECD method, numbers of HAR architectures including nanorods, nanofins and even mushroom-like structures, which have a line width as small as 100 nm and the aspect ratio up to 10:1, are established over a large scale. What is more, by simultaneously considering the designed layout and edge effect, sub 10 nm nanogap arrays are prepared, whose aspect ratio reaches 100:1 and the gap width reduces to 5 nm. Due to the extreme light confinement ability brought from Fabry–Perot resonance, the HAR nanogaps can be treated as a surface enhanced Raman scattering (SERS) substrate. Finite domain time difference simulation shows that fan-like 10 nm nanogap with a height of 700 nm has the largest light enhancement factor (EF). The configuration optimized nanogap is capable for the sensing of rhodamine 6G with a 10−9 M concentration. And the SERS EF of the nanogap is calculated to be 4 × 106, indicating the ultrasensitive molecular detection ability of the HAR nanogap. The templated ECD method not only brings a new chance for the construction of HAR metallic 3D structures, but also opens up a new horizon for the design of a series of plasmonic devices.

With continuous fossil energy consumption and global warming, renewable energy has become more popular. Therefore, more and more researchers have begun to study hydrogen-based hybrid renewable energy systems. This article mainly summarizes the commercial software tools and the simulation of hybrid renewable energy systems in recent years. Firstly, the commonly used softwares and research methods are reviewed so that other researchers can choose suitable tools and strategies to conduct their researches. Then TRNSYS software is used to perform a case study in Yichang, Hubei, China. The established model is simulated according to the one-year load of the community. The simulation results show that the total power generation of the system can meet the load demand most of the time but is insufficient in some peak periods. The system can further be optimized using optimization methods to fully meet the load.

To look for alternative fertilizer products, the application of wheat straw was explored in different forms instead of chemical fertilizer. The N, P, K, organic matter, humus, pH, germination rate in soil were determined to observe the effect on soil fertility. The results indicate that biochar had the best effect on soil fertility when straw was returned to the field in different forms; the effect of biochar on increasing the content of soil organic matter and humus was more obvious than the nitrogen fertilizer; biochar has little difference in total potassium; biochar has the most obvious effect on increasing the content of total nitrogen and available phosphorus. As a new type of fertilizer, biochar can replace chemical fertilizer which causes damage to soil environment. Biochar has the ability of fixing carbon and can slow down the greenhouse effect.

For the current demand for live broadcast and live video in colleges and universities, relying on the advantages of campus network, this paper designed and implemented a video live broadcast and video on-demand system suitable for colleges and universities. The system used the streaming media server built by the open source Nginx to capture high-definition video streams output by cameras, etc. through the RTMP protocol, and can provide video live broadcast and video on-demand services using multiple carrier lines. Video live broadcast used the open source Flash player JW Player, stored video in high-performance HDFS distributed storage at a certain time interval and format by a storage algorithm, and supported on-demand playback of MP4 format video stored in HDFS. The paper tests the various functional modules of the system and the overall performance of the system to verify the effectiveness of the system. The system is currently deployed in the campus network of Xi’an Jiaotong University, providing normal recording and broadcasting of video of 293 intelligent classrooms in Xi’an Jiaotong University, video on-demand for after-school courses, video live broadcast and video on-demand for various large-scale events held on campus.

China’s renewable resources have the characteristics of reverse distribution, under the background of large-scale development of renewable energy consumption, we should break the existing administrative regional barriers of renewable energy electricity consumption across provinces. In order to accelerate the promotion of renewable energy consumption liability mechanism, an effective curve declaration and clearance model should be proposed. Based on the theory of time-division clearing, this paper makes some improvements in declaration and clearing. Two models are proposed, namely the time-division declaration model and the proportional declaration model. In addition, two clearing methods under different curve declaration decomposition methods are proposed, namely time-division matching clearing method and marginal clearing method. Based on the above theory, the organization methods of power grid and power right transferor and transferee are proposed to promote the optimization of power supply structure and the consumption of renewable energy.

Polycrystalline BAsx (x = 0.80–1.10) compounds with different boron-to-arsenic elemental molar ratios were synthesized by a high-pressure and high-temperature sintering method. Compared with other ambient-pressure synthesis methods, high pressure can significantly promote the reaction speed as well as the reaction yield. As the content of arsenic increases from x = 0.91 to 1.10, the thermal conductivity of BAsx gradually increases from 53 to 65 W⋅m −1⋅K −1. Furthermore, the temperature dependence of thermal conductivities of these samples reveals an Umklapp scattering due to the increasing phonon population. This work provides a highly efficient method for polycrystalline BAs synthesis.

The cracking Booster pump shaft is carried out macroscopic examination, crack analysis, metallographic examination, chemical composition analysis, mechanical properties (tensile, impact) analysis, and combined with the pump shaft installation and operation, determine the direct cause of shaft cracking is crevice corrosion, the root cause include O ring in booster pump machine seal sleeve does not meet the requirement, O ring installation damage, and the clearance between pump shaft and machine seal sleeve is too small. According to the root cause of the pump shaft cracking, relevant corrective actions have been formulated, such as changing model of O ring in booster pump machine seal sleeve, change the clearance between pump shaft and machine seal sleeve, increase anti-corrosion coating or protective sleeve on pump shaft etc.

Pressure variations during fluid transients in pipelines are of significant interest to hydraulic engineers and scientists. To clarify the effects of unsteady wall shear stress on the propagation of pressure waves, we re-examine an analytical solution that was recently developed with unsteady wall shear stress included. Physical insights about the effects of unsteady wall shear stress are obtained. Comparisons of the solution with available experimental data and the numerical results of an instantaneous-acceleration-based model are carried out. It is found that unsteady wall shear stress can cause both the amplitude decay and phase shifts of the water hammer pressure. The phase shifts caused by unsteady wall shear stress are indicated by the deformation of pressure variations. Furthermore, we highlight that for initial-laminar and low-Reynolds-number flow conditions, the effect of unsteady wall shear stress is independent of the initial Reynolds number but is related to another dimensionless parameter that has a clear physical significance; that is, the ratio of viscosity diffusion time to the period of water hammer or the ratio of boundary layer thickness to the pipe radius.

Lanthanum telluride (La_3Te_4) is an n-type high-performance thermoelectric material in the high temperature range, but its mechanical properties remain unknown. Since we want robust mechanical properties for their integration into industrial applications, we report here quantum mechanics (QM) simulations to determine the ideal strength and deformation mechanisms of La_3Te_4 under pure shear deformations. Among all plausible shear deformation paths, we find that shearing along the (0 0 1)/〈100〉 slip system has the lowest ideal shear strength of 0.99 GPa, making it the most likely slip system to be activated under pressure. We find that the long range La–Te ionic interactions play the predominant role in resisting shear deformation. To enhance the mechanical strength, we suggest improving the long ionic La–Te bond stiffness to strengthen the ionic La–Te framework in La_3Te_4 by a defect-engineering strategy, such as partial substitution of La by Ce or Pr having isotypic crystal structures. This work provides the fundamental information to understand the intrinsic mechanics of La_3Te_4.