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Using lignocellulosic biomass wastes to produce Hydrogen for the sustainable Hydrogen Economy can help reduce or eliminate the current heavy dependence on fossil energy. We hereby report a new pathway for H2 synthesis by simply applying commercial SrTiO3 catalyst in photoreforming processes following thermo-alkaline hydrolysis (TAH) pretreatment. Thanks to the thorough decomposition of the lignocellulosic matter under an optimized TAH condition, the obtained hydrolysate shows superior ability to produce H2. Its H2 production capacity is much better than that of TEOA and TEA, for which the cellulose hydrolysate was twice that of TEOA and 12 times that of TEA. This remarkable improvement is attributed to the selective formation of an important intermediate product, tartaric acid, which is for the first time identified as the key to enhancement of H2 generation from catalytic photoreforming processes. © 2022

Abstract Knowing the efficiency of a hydraulic turbine has important operational and financial benefits to those who operate a plant. Historical efficiency and other data on turbine performance are essential for the informed selection and use of turbines. So having such a database from different manufactures is attractive. However, at present it is almost impossible to get a universal database to reflect the turbine characteristics. This paper reviewed a set of empirical equations to replacefull database which defines the peak efficiency and shape of the efficiency curve as a function of the commissioning date for the unit, rated head, rated flow and other main design parameters. Since the design theories, methods and tools of turbines are relatively mature, and the majority of turbine manufacturers have reached a level of know how which enables them to carry out hydraulically and structurally correct units to product high-performance turbines. This paper paid more attention to the design factors, which could influence the value of the practically attainable overall turbine efficiency. To quantify the effects of these factors, this paper investigated the influence of roughness and gap clearances on the internal leakage flow rate. Testing and CFD are the most two important tools in different design stages. This paper reviewed some key ideas and issues on the efficiency research in both. At last, improvement measures based on these above mentioned design factors were provided.

Abstract Attached microalgae cultivation is an effective way to decrease the high harvesting cost in microalgae biomass production. Nitrogen and phosphorus, as the two main nutrients, are hypothesized to influence the attachment efficiency and growth of microalgae. The attached growth of Scenedesmus. LX1 in the suspended-solid phase photobioreactor (ssPBR)1 with feed composed of different total nitrogen (TN) and total phosphorus (TP) concentrations was studied in this paper. The productivity of attached microalgae on Day 3 (3 × 106 cells·cm−3) at the nutrient levels of TN = 15 g m−3 and TP = 5 or 3 g m−3 was approximately 70% higher than that at relatively high-nutrient levels (i.e. TN = 150 g m−3 and TP = 10 or 15 g m−3). Under the nutrient levels of TN = 15 g m−3 and TP = 5, 3, 1.5, 0.5 g m−3, the average TN and TP concentrations in the microenvironment around microalgae biofilm were about 2.1 and 15.5 times higher than those of the bulk media, respectively. The higher nutrient concentration in the surrounding microenvironment of microalgae biofilm improved protein synthesis of attached microalgae compared to the suspended ones within the same reactor, especially at the late stage of batch cultivation.

The increasing amount of data recorded during power system operations and recently developed data-driven methods make online sensitivity identification (SI) a possibility. However, due to the inherent properties of power systems—nonlinearity, time variance, and collinearity—the effective data that carry the sensitivity information are insufficient. Consequently, the online SI information collected with existing methods may result in unexpected estimates. In this paper, a sufficient effective data condition that guarantees the success of online SI is proposed. The inherent properties of power systems and their impacts on this condition are then investigated. A series of metrics to qualify online whether the data meet the condition is put forward to assess the online SI results. A method is also proposed to select the effective data to improve the online computational efficiency. Finally, the findings and methods are validated in an eight-generator 36-node bus system with operations data recorded from actual power systems.

Measurement sensors installed in the smart transmission system can acquire big data for electromechanical dynamics monitoring. The time-series data obtained carry information of instantaneous relationship of system oscillation modes with respect to operating conditions. To extract this information, this paper proposes a parallel processed online supervised learning algorithm called k-nearest neighbors “locally weighted linear regression” (KNN-LWLR), which is an extensive combination of two famous machine-learning algorithms: 1) the KNN learning; and 2) LWLR learning. Its mathematical derivation, implementation, parameter tuning, and application to electromechanical oscillation mode prediction are first described. The proposed algorithm is then validated based on an 8-generator 36-node system with the real operations data.

The factors affecting the ignition temperatures of two low-rank coals were experimentally studied using thermogravimetric analysis. The experiments were conducted with coal powders of four different particle size distributions. The thermogravimetric analyzer was operated at three heating rates, 10, 20, and 30 °C min−1 and four oxygen concentrations of 3, 6, 9, and 12%. The results showed that the ignition temperature decreased by about 25 °C as the oxygen concentration increased from 3% to 12%. The standard deviation of the activation energy was 16.75% at a conversion degree of less than 0.4, and it decreased to 1.35% at the end of the combustion process. At a heating rate of 10 °C min−1, the ignition temperature increased by about 8 °C as the coal particle size increased by 100 μm. At a heating rate of 30 °C min−1, the effect of the particle size on the ignition temperature was enhanced and the ignition temperature increased to 15 °C.

Abstract A simple and systematic procedure for decentralized stabilizer design for multimachine systems is presented in this paper. The procedure first selects the most effective location of a stabilizer according to a machine stability index. The parameters of the stabilizer are then determined by a decentralized feedback control scheme. This process is carried out for one stabilizer at a time. The resultant overall improvement of the system stability, measured by a system stability index, is used to decide how many stabilizers are required for the system. The proposed technique is illustrated by a test system. Both eigenvalue analysis and nonlinear simulation are performed to investigate the effectiveness of the technique.

Abstract This paper presents a thorium fuel cycle scheme for the thorium-based advancednuclear energy system JANES). TANES that will use thorium resources is a homemade nuclear energy system that is fit for the situation of China and some other thorium-rich regions. By the reactor physics and fuel cycle analysis, the paper gets the conclusion that if TANES decreases lattice pitch (channel pitch) and increases driver fuel enrichment, TANES will provide a slightly negative coolant void reactivity coefficient to facilitate implementation of advanced automatic control technology.