Three Relationships Must Be Balanced to Expand Domestic Demand

The slower expansion of domestic demand has put pressure on economic growth as the Chinese economy enters a new normal stage. Since the industrial structure can only be effectively upgraded through appropriately expanding aggregate demand, three relationships must be balanced:

Intrinsic physical relationships between rotor modal shapes and instantaneous vibrational energy flow transmission characteristics:Theoretical and numerical analysis and application

The modal vibration of the rotor is the main cause of excessive vibration of the aeroengine overall structure.To attenuate the vibration of the rotor under different modal shapes from the perspective of energy control,the intrinsic physical relationships between rotor modal shapes and instantaneous vibrational energy flow transmission characteristics is derived from the general equation of motion base on the structural intensity method.A dual-rotor-support-casing coupling model subjected to the rotor unbalanced forces is established by the finite element method in this paper.The transmission,conversion and balance relationships of the vibrational energy flow for the rotors in the first-order bending modal shape,the conical whirling modal shape and the translational modal shape are analyzed,respectively.The results show that the vibrational energy flow transmitted to the structure can be converted into the strain energy,the kinetic energy and the energy dissipated by the damping of the structure.The vibrational energy flow transmission characteristics of rotors with different modal shapes are quite different.Especially for the first-order bending modal shape,the vibrational energy flow and the strain energy are transmitted and converted to each other in the middle part of the rotor shaft,resulting in large deformation at this part.To attenuate this harmful vibration,the influences of grooving on the shaft on the first-order bending vibration are studied from the perspective of transmission control of vibrational energy flow.This study can provide theoretical references and guidance for the vibration attenuation of the rotors in different modal shapes from a more essential perspective.

Operando reconstruction-induced CO_(2)reduction activity and selectivity for cobalt-based photocatalysis

The oxygen atom coordination inducing the structure reconstruction of the catalytic site is identified and recognized ambiguously,which is related to accurately declare the mechanism in a dynamic catalytic process.Herein,we demonstrated that the reconstructed catalytic sites would lead to a remarkable performance for photocatalytic CO_(2)reduction.At the initial 4-cycles testing,the in-situ formation of CoOx active sites on the Co(CoP)surface performed an increasing transient activity and selectivity toward CO evolution.The formation of reconstructive Co-O bond and the appearance of intermediate specie CO were simultaneously observed by the pre-operando Raman,revealing the dynamic relationship between catalytic site structure and the photocatalytic properties.Moreover,density functional theory calculations showed that the electronic structure of the reconstructive surface sites could modulate the ability of CO_(2)adsorption and CO desorption.The reduced barrier energy for the rate-determining step finally improved the activity and selectivity of CO_(2)reduction.

Applicability and comparison of solar-air source heat pump systems between cold and warm regions of plateau by transient simulation and experiment

Solar-air source heat pump(solar-ASHP)system has a potential application in the field of hot water and space heating in residential buildings.Such system features the complementary advantages to solve the discontinuous operation of the single solar system and the frosting issue of the single ASHP system.This paper built the solar-ASHP systems in Kunming and Shangri-La,and tested the system performance under different weather conditions in these two regions of plateau.Meanwhile,the transient heat balance models of the system were established under the sunlight time and non-sunlight time and were verified by the experimental results.Moreover,the verified model was applied to reveal the energy balance performance between the energy supply and building heat demand.The law of the system performance affected by the ambient temperature,effective heat collecting area,and cumulative heating capacity of collector was explored by the validated model.The results indicate that when the ambient temperature decreases by 1℃during non-sunlight time,the energy efficiency ratio decreases by about 0.07.A square meter decline in the effective heat collecting area pushes an increase in the heating capacity of 5.75 MJ.Meanwhile,the cumulative heating capacity of collector increases by 5 MJ,and the ASHP energy consumption decreases by 0.54 kWh.The dynamic changes of the ambient temperature and instantaneous solar radiation are the main reasons of the heat balance errors.Therefore,both the developed system and model are feasible and reliable in different climate regions.