Top10 engineering research frontiers in mechanical field

(6) optimization of the global navigation satellite system

Global satellite navigation and positioning system (GNSS) is widely used in military, navigation, surveying and mapping, exploration, transportation and other fields. In recent years, GNSS technology has been widely used in automobile navigation, smart phones and other consumer products, showing a broad application prospect in cities. GNSS technology achieves position estimation by extracting "pseudo-distance" parameters from multiple navigation satellite signals. However, due to the high density of buildings in the city, some barriers and interference to satellite signals will be formed, which will affect the positioning accuracy and response speed of GNSS. Therefore, it is very difficult to improve the robustness of GNSS in urban working conditions and optimize the positioning and navigation accuracy. In recent years, GNSS technology has made a lot of achievements in improving positioning accuracy and corresponding speed based on urban road conditions. Among them, new technologies such as 3d building model aided prediction, digital map aided identification, and shadow matching positioning algorithm have played an important role in the development of high-precision positioning in cities, greatly improving the reliability of GNSS. In addition, GNSS technology is also affected by a series of complex working conditions, such as urban viaducts, Bridges and tunnels, and still faces severe challenges.

(7) cognitive wireless network

Cognitive wireless network is an advanced network technology developed on the basis of wireless network. Its core idea is to realize dynamic spectrum allocation through spectrum perception, autonomous decision and network reconstruction, so as to improve the utilization efficiency of spectrum resources and adapt to the dynamic changes of network. Spectrum sensing is to obtain free available frequency band by detecting spectrum usage information in wireless network. Independent decision-making and network reconstruction are to analyze available spectrum resources, adjust network parameters according to real-time changing user demand and spectrum utilization strategy, and realize adaptive allocation of spectrum resources. In recent years, cognitive wireless networks have developed in several new directions. Firstly, the combination of cognitive wireless network and power transmission enables the network to transmit information and power at the same time. Secondly, cooperative relay is introduced in cognitive radio network. Secondary users act as relay to help primary users transmit data cooperatively and carry out information cooperation. In the future Internet of things and intelligent transportation, dense wireless sensors and intelligent vehicles will cause explosive growth of communication demand and shortage of wireless spectrum resources. Cognitive Internet of things and cognitive Internet of vehicles proposed based on cognitive wireless network will play an important role in alleviating spectrum resource pressure.

(8) tactile target recognition

The robot realizes the perception of the external environment or the target object through the tactile sensor of the fingertips. Tactile sensing can capture multiple object attributes, such as texture, roughness, spatial characteristics, flexibility or friction, etc., thus becoming a very important sensing mode in the field of intelligent robots. Tactile - based environmental perception plays an important role in delicate operation and contact - sensitive submarine welding. In the actual robot operation, the manipulator usually has multiple fingers and tactile data of different fingers constitute a sequence. By using the display advantages of the tactile sequence data set and considering the internal relations between multiple fingers, the joint core sparse coding model and the core dictionary learning method are developed, which are helpful to improve the haptic object recognition performance. In addition, with the rapid development of intelligent robot technology, people are eager to give robots like human skin tactile perception ability, in order to improve the performance of the intelligent bionic robot, so the research of flexible tactile sensor has become the forefront of tactile sensing technology content, the research and development of flexible multidimensional tactile sensor is one of the important and difficult.

(9) assessment and utilization of offshore wave energy resources

Offshore wave energy, as a kind of renewable and clean energy, has the characteristics of high energy density and wide distribution. Its development and utilization will play a great role in solving the problems of energy crisis, environmental pollution and climate change. The scientific research on inshore wave energy mainly focuses on two aspects: one is to effectively evaluate the inshore wave energy reserves and spatial and temporal distribution, so as to provide effective guidance for the site selection of wave energy power station and the design of wave energy conversion device; The second is the design, development and experiment of wave energy conversion device. At present, in the world's sea wave field analysis and wave energy resources assessment, the wave numerical simulation is to obtain the principal means of wave parameters, but its forecast precision is restricted by many factors, for complex wave field simulation ability is limited, there are certain gap with the field observation data, so still need to look for a long time, it can get a wide range of the waves the results of field observation method to improve the accuracy of the assessment, enrich assessment means. In addition, due to the complex and changeable Marine environment, the wave energy itself is unstable, with large reserves, wide distribution and difficult to use, etc., the wave energy conversion device applied in the ocean is also vulnerable to Marine catastrophic climate. Therefore, offshore wave energy resources assessment using and development of the theory research and equipment development, etc., there are a lot of difficult problems needed to solve, such as raising the wave energy resource assessment and prediction of comprehensiveness and accuracy, and to optimize the design of the wave energy device, increase response speed and wave energy device conversion efficiency and improve the wave energy device stability and reliability, reduce the cost of manufacture and installation, etc.

(10) electric/magnetic fields enhance the convective heat transfer of nanofluids
Nanofluid is a new type of heat transfer and cooling medium formed by adding nanoparticles into the fluid. It has high thermal conductivity and good fluid followability. Applying it to convection heat transfer can obviously improve the heat transfer effect of the system. In recent years, on the basis of traditional nanofluids, the further use of electric/magnetic fields to enhance convective heat transfer has gradually become the forefront of research at home and abroad. At present, with the aid of the theory and numerical simulation method, this paper expounds the in electrical/magnetic field under the action of nanofluids respectively as the convection heat transfer characteristic of single-phase flow and multiphase flow, reveals that the particle size, shape, surface properties, chemical properties of particles and liquid and electrical/magnetic field characteristic parameters, such as the influence law of convection heat transfer of nanofluids. However, due to the rather complex mechanical and flow conditions of the nanoparticles in the electric/magnetic field, it is difficult for the proposed theoretical and simulation models to fully consider the influencing factors of convective heat transfer. Therefore, it is necessary to adopt advanced and accurate test methods to conduct experimental research on the convection heat transfer of nanofluids strengthened by electric/magnetic field, accumulate abundant experimental data, and further improve the model of convection heat transfer of nanofluids under the action of electric/magnetic field. On this basis, the mechanism of the effect of electric/magnetic field on the convective heat transfer of nanofluids is described, which is expected to promote its application in industry.