• Energy Research
• other engineering and technologies close
• GB close
• EU close
• CN close
• AU close
• English close

We propose an on-the-fly statistical learning method to make a qualitative reduced-order model of the dynamics of a premixed flame quantitatively accurate. This physics- informed data-driven method is based on the statistically optimal combination of (i) a reduced-order model of the dynamics of a premixed flame with a level-set method, (ii) high-quality data, which can be provided by experiments and/or high-fidelity simulations, and (iii) assimilation of the data into the reduced-order model to improve the prediction of the dynamics of the premixed flame. The reduced-order model learns the state and the parameters of the premixed flame on the fly with the ensemble Kalman filter, which is a Bayesian filter used in the data assimilation of high-dimensional dynamical systems, e.g., in weather forecasting. The proposed method and algorithm are applied to two test cases with relevance to reacting flow and instability. First, the capabilities of the framework are demonstrated in a twin experiment, where the assimilated data are produced from the same model as that used in prediction. Second, the assimilated data are extracted from a high-fidelity reacting-flow direct numerical simulation (DNS). The results are analyzed by using Bayesian statistics, which provide the uncertainties of the calculations. This method opens up new possibilities for on-the-fly optimal calibration of computationally cheap reduced-order models when experimental data become available, for example, from sensors.

In recent years, in order to promote the independent development of the new energy vehicle industry, Chinese government has decided to reduce the consumption subsidies for new energy vehicles until the subsidies are completely withdrawn. The reduction of consumption subsidy has a great impact on the production and sales of new energy vehicles in the whole vehicle market. However, does the reduction of this subsidy also have an impact on other enterprises in the new energy vehicles industry chain? This paper tests this problem using data from 2016 to 2018, and finds, through empirical analysis, that during the period of subsidy decline, the profitability of component enterprises is significantly positively correlated with this subsidies, while the r&d investment of enterprises is significantly negatively correlated with this subsidies. The results show that in terms of profitability, the reduction of consumer subsidies not only has an impact on the whole vehicle industry of new energy vehicles, but also has an adverse impact on the core component companies in the industrial chain. However, in terms of r&d, the reduction of subsidies has more negatively strengthened the input and attention of R&D in component companies.

ON 16 NOVEMBER 2000, the final report of the World Commission on Dams (WCD) was launched in London, in the presence of South Africa’s former president Nelson Mandela. This represented a remarkable milestone in the history of dam policy and politics. During its two-year existence, WCD had conducted the most extensive review of research and evidence regarding the planning, impacts, and management of large dams. It had engaged with numerous stakeholders around the globe. It also made comprehensive recommendations about how to improve dam planning and management.

We have attained superior quality a-SiGe:H and nc-Si:H materials deposited at high rate, ~0.6 nm/s for a-SiGe:H and 1-1.5 nm/s for nc-Si:H, and achieved improved multi-junction solar cell performance. For a-SiGe:H based cells, we have focused our effort on further improving the a-SiGe:H film quality by carefully optimizing process parameters, particularly with Ge content and profile, hydrogen dilution, deposition pressure and substrate-tocathode distance, to fabricate a-SiGe:H films with low defect density and good stability. For nc-Si:H based solar cells, we have mainly worked on improving the spatial uniformity and homogeneous properties for nc-Si:H deposition, and on optimizing the plasma process and selecting species to deposit further improved nc-Si:H. We attained 10.1% and 11.2% stabilized efficiencies, respectively, for large-area (≥400 cm2) encapsulated a-Si:H/a-SiGe:H/a-SiGe:H and a- Si:H/nc-Si:H/nc-Si:H triple-junction cells. Comparison between a-SiGe:H and nc-Si:H based technologies and future improvement will be presented. 25th European Photovoltaic Solar Energy Conference and Exhibition / 5th World Conference on Photovoltaic Energy Conversion, 6-10 September 2010, Valencia, Spain; 2783-2787

This paper presents a research work carried out under the umbrella of the CASCADE project, which is a European FP7 research project which is developing facility-specific measurement-based energy action plans for the airport energy managers that are underpinned by Fault Detection Diagnosis (FDD). The paper first describes the context of the project then it focuses on Building Management Systems describing the current status of the technology and presenting an outlook on their future development. Then a Strengths Weakness Opportunity and Treads (SWOT) framework is defined with the aim of verifying the suitability of an installed BMS system to incorporate Fault Detection and Diagnosis (FDD) tools

Programmed Logic Controller (PLC) is the digital calculation operation system, which is specially designed for industrial working environment. This paper proposed the implement of hydraulic control system for large-scale railway maintenance equipment based on PLC. This implement pursued the purpose of accurate control of hydraulic working units of large-scale railway maintenance equipment. Large-scale railway maintenance equipment should always work in efficient statement. Focusing on this requirement, the reliability design of hardware for current leakage and impulse current which is proposed in the paper is necessary. This paper proposed Triple Modular Redundancy (TMR) for relative horizontal check of working units linking bridge. This paper also proposed the method to prevent the current leakage and impulse current. As for hydraulic valves, this paper proposed PID algorithm to realize the control of Analogue Closed-Loop.

In order to develop the technology of carbon dioxide at so-called supercritical state (sCO2) further, quick and reliable design tools for the different system components, e.g. centrifugal compressors, are required. In this study, a computer program is developed to predict the performance of centrifugal compressors with sCO2 as working fluid. This computer program is based on mean-line analysis, calculates the fluid parameters at selected sections of the meridional plane and plots the performance maps. So-called enthalpy loss coefficients are utilized to describe the difference between the isentropic and the polytropic process. In addition to previous studies, the presented model intends to predict the performance of sCO2 centrifugal compressor with a shrouded impeller and a vaneless diffuser. For this purpose, corresponding loss coefficients are incorporated. Subsequently, the predicted results of this work are compared and validated with computational fluid dynamics (CFD) and experimental results from the EU-project sCO2-HeRo. The prediction of the computer program fits within 5% deviation to the CFD results, and about 4% to the experimental results regarding to pressure ratio. Conference Proceedings of the European sCO2 Conference4th European sCO2 Conference for Energy Systems: March 23-24, 2021, Online Conference, p. 68

It has to be considered that dynamic performance of Super Capacitor and Battery hybrid energy storage system is poor and the output waveform of AC voltage distorted seriously. The Third Harmonic Injection PWM (THIPWM) with the three-level inverter, which has a excellent performance to improve the dynamic performance of the super capacitor and battery, gathers information from ends of the DC output voltage or current and the total current of the DC side to solve the problem of unbalanced neutral line voltage of three-level inverter .It also keeps super capacitor and battery controlled smoothly during the operation, and reduces the final output waveform distortion index. The simulation results verify the practicality and correctness of the three-level inverter topology and its control algorithm.

Over the past few years, remarkable developments in piezoelectric materials have motivated many researchers to work in the field of vibration energy harvesting by using piezoelectric beam like smart structures. This paper aimed to present the most recent application of a dual function piezoelectric device which can suppress vibration and harvest vibration energy simultaneously and a brief illustration of conventional mechanical and electrical TVAs (Tuned Vibration Absorber). It is shown that the proposed dual function device combines the benefits of conventional mechanical and electrical TVAs and reduces their relative disadvantages. Conversion of mechanical energy into electrical energy introduces damping and, hence, the optimal damping required by this TVA is generated by the energy harvesting effects. This paper presents the methodology of implementing the theory of 'electromechanical' TVAs to suppress the response of any real world structure. The work also illustrates the prospect of extensive applications of such novel "electromechanical" TVAs in defence and industry. The results show that the optimum degree of vibration suppression of an electronic box is achieved by this dual function TVA through suitable tuning of the attached electrical circuitry