Search

It is difficult to solve the binding force of motion pairs of over-constrained mechanisms. This study attempted to decompose the constraint term in the d'Alembert principle into two parts, static constraint and dynamic constraint. The static constraint under constraint conditions and the dynamic constraint of the equilibrium inertial force were obtained separately, and the total constraint force of the example was solved through the superposition of the two. Taking three pairs of uniform transmission rod space RCCR mechanism as the research object, the binding force was solved by the above method, and the solution results were compared with the dynamic simulation results. The results show a good consistency.

【Objective】 Change in soil water content is not only an indicator of water stresses used for irrigation management but also controls biogeochemical processes in soil. In this paper, we study the feasibility of using thermal infrared imaging to estimate soil moisture dynamics. 【Method】 The experiment was conducted in July-August 2023 in a walnut orchard in Xinjiang. Thermal infrared images of the walnut canopy were measured continuously using a thermal infrared camera. Based on the HSV color space of the images, an improved K-means segmentation algorithm was proposed to analyze the change in canopy temperature. We also measured air temperature and humidity, illuminance, wind speed, atmospheric CO2, and soil water content in the 0-80 cm soil layer, from which we proposed an inversion model to estimate soil water dynamics. 【Result】 The improved K-means algorithm increased the accuracy from 82.34% to 94.55%, and the errors between the canopy temperature acquired from the images and the measured canopy temperature were in the range of 0 to 1.0. The infrared imaging method was most accurate between14:00 pm to 16:00 pm. Our results showed that the walnut roots were most active in taking up water from the 40-60 cm soil layer 50-60 cm away horizons from the tree truck. Canopy temperature, air temperature and relative humidity, and atmospheric CO2 concentration were correlated with soil water content at significant levels; they can thus be used to estimate soil water dynamics, with a coefficient of determination of R2=0.86 and p

In this paper, 66 samples belonging to 12 varieties of domestic high-gluten wheat in 2021 were collected, and their physicochemical, rheological and bread sensory properties were analyzed. The results of the main component analysis showed that the total sensory score of bread had a strong correlation with gluten index, maximum tensile resistance, mixing time, stretching area and stabilization time, etc. At the same time, the screening of wheat varieties with high similarity through cluster analysis could play a key guiding role in the development and maintenance of production stability of baking special flour. Comparing the fitting quality of the bread total sensory score prediction model established by the three methods of stepwise regression, partial least squares and neural network model, the model built using artificial neural network was significantly better than other models. Using neural network models, the baking characteristics of different varieties of wheat could be quickly predicted, ensuring product stability, while also facilitating the development of more targeted baking special flours.

Surface modification of poly(benzoxazole-imide) (PI) film was carried out by means of oxygen plasma treatment. A flexible copper clad laminate (FCCL) was fabricated using Ni-Cr ion implantation and electro-Cu plating process. Controlling the constant pressure, the effects of such treatment conditions as power and time were systematically investigated on the surface roughness, chemical composition and interface adhesion with Cu. It is found that the optical parameters for production of FCCL with excellent adhesion and solder resistance are 50 W/5 min and 100 W/10 min, respectively. Suitable roughness, reactive radical with high content pendent oxygen group, and metal-oxazole complex help to endow exceptional adhesive property to the interface of PI/Cu. And the peel strength of FCCL prepared from PI film with such modified surface rises by 60%.

Sorafenib resistance has been a major factor limiting its clinical use as a targeted drug in liver cancer. The present study aimed to investigate whether cryptotanshinone can enhance the sensitivity of liver cancer and reduce the resistance to sorafenib.

[Purpose/significance] In the era of mobile internet, people expect to acquire knowledge services through mobile terminals, and the mobile institutional repository is an important carrier and channel. As an office tool for internal communication, enterprise Wechat gradually integrates into the Wechat ecosystem and is applied by more units and organizations. [Method/process] Taking the construction of mobile institutional repository of China Academy of Information and Communications Technology (hereinafter referred to as “CAICT”) as an example, this paper analysed the application requirement, put forward the construction mode of “Enterprise Wechat + Web APP”, introduced in detail the process of system design and realization of main functions, and analysed the system effect and experience summary. [Result/conclusion] Starting from individual practice, this paper explores the mode of "Enterprise Wechat + Web APP" to build Mobile Institutional Repository, which is fast release, easy to use, high efficiency, low cost, universal and replicable, and has certain reference significance for other knowledge service organizations.

Graphene, as a rising star in materials science, is intensively studied in Li-ion batteries and supercapacitors, owing to its unique structure and excellent properties. The research status of the application of graphene in energy storage field was disscussed and the future development trend was predicted, and therefore to enhance the understanding of the structure-performance relationship of graphene and also the application of graphene in this field. Firstly, the application of graphene in cathode and anode of Li-ion battery, and the application of graphene in electrical double-layer capacitor and pseudo-capacitor were introduced. Secondly, the challenges of graphene in electrical double-layer capacitor were discussed and the ideal structure of graphene applied to electrical double-layer capacitor was proposed. Finally, the "three steps" to realize the commercial application of graphene-based electrical double-layer capacitor were put forward.

The bulky electrolytic capacitor is conventionally used to curb the output voltage ripple of output DC-link in the front-end PFC AC/DC converter, which is applied for the on-board charger of the electrical vehicle. Due to the drawbacks of electrolytic capacitor, such as the short lifetime, susceptibility to temperature and other reasons, the reliability and usage cycle of on-board charger are reduced, even leading to the system breakdown. In order to decline the output voltage ripple in the output DC-link, the PFC AC/DC converter paralleled with power decoupling circuit at the output side is proposed, ensuring safe and reliable operation in the on-board charger. It contributes to diminish the volume of output filtering capacitor sharply and utilize the excellent film capacitor instead of the electrolytic capacitor. In this paper, the mathematical model of power decoupling circuit is established based on the detailed analysis of the circuit operation. Besides, the improved PR(Proportional Resonant) controller is designed to dominate the power decoupling circuit. In order to improve the control performance and robustness, the model-free nonlinear power control strategy is implemented to the PFC AC/DC converter. Based on the aforementioned researches, a 700 W experiment prototype is developed. The feasibility and efficiency of the proposed method are validated by the DSPACE 1007 test platform.

To overcome the shortcomings of the full-bridge DC/DC converter topology for on-board charger, an improved phase-shifted full-bridge converter topology is suggested，and its working principle is analyzed when it operates in the discontinuous current mode(DCM), the key components parameters design is researched in the condition of 2 kW operating conditions, and then, the switching element average model method is proposed to set up the ideal small-signal model of improved phase-shifted full-bridge converter operating in DCM, moreover, the sweep frequency method is used to validate the rationality of modeling methods and established models.

Using bushings with great stiffness coefficient to replace the rigid constraints,the dynamics simulation of the over-constrained spatial RCCR mechanism with three pairs of force transmitting rods under conditions approaching rigidity is achieved.The simulation experiment targeting different structural parameters and resistance moment,the variation discipline of transmitted force is obtained,the cosine function type of constraint component Fz is fitted out,the estimation formula of Fz amplitude is summed.

The deformation compatibility equation is built on the basis of the flexible treatment of the forcing pair,and the static binding force of forcing pairs of three pair bars space RCCR mechanism is solved under the condition of close to rigid body.The result is more concise and closing to the ideal state compared with that on the basis of the flexible treatment of the forcing bars.