Results 1 - 10 of 694
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[en] Highlights: • Triboelectric nanogenerator was prepared using force-assembled colloidal arrays. • The electrical performance was determined by the structures and colloidal size. • They displayed high electric output, stability, and humidity resistance. We introduce a novel, robust, cost-effective, and scalable approach for the preparation of a large-area force-assembled triboelectric nanogenerator (FTENG), which allows a stable and high electric output under a wide range of humidity conditions through its dual-sized morphology (i.e., microstructures and nanostructures). In this study, hexagonally packed colloidal arrays prepared by a force assembly approach rather than by conventional self-assembly were used as a mold for a triboelectric poly(dimethylsiloxane) (PDMS) replica with desired pattern shapes (intaglio and embossed structures) and sizes. The morphological size of the PDMS films was determined by the diameter of the force-assembled colloids. The electrical output performance of FTENGs composed of electrodes and a PDMS film increased substantially as the size of the micropores (for intaglio-structured PDMS) or embossed features (for embossed-structured PDMS) decreased. Furthermore, the triboelectric PDMS film with micro-/nanosized features (i.e., dual-embossed PDMS) displayed a remarkable electrical output of 207 V (open-circuit voltage under a compressive force of 90 N in relative humidity (RH) of 20%) and high hydrophobicity compared to that of PDMS films with flat, intaglio or embossed structures. This device maintained a high electric output even in a high-humidity environment (i.e., open-circuit output voltage ~175 V in RH 80%). Our approach using force-assembly and hierarchical surface morphology will provide a novel and effective framework for developing strong power sources in various self-powered electronics.
[en] Distributed generation (DG) is small generating plants which are connected to consumers in distribution systems to improve the voltage profile, voltage regulation, stability, reduction in power losses and economic benefits. The above benefits can be achieved by optimal placement of DGs. A novel nature-inspired algorithm called Dragonfly algorithm is used to determine the optimal DG units size in this paper. It has been developed based on the peculiar behavior of dragonflies in nature. This algorithm mainly focused on the dragonflies how they look for food or away from enemies. The proposed algorithm is tested on IEEE 15, 33 and 69 test systems. The results obtained by the proposed algorithm are compared with other evolutionary algorithms. When compared with other algorithms the Dragonfly algorithm gives best results. Best results are obtained from type III DG unit operating at 0.9 pf.
[en] This paper designs a kind of Piezoelectric liquid resistance capture energy device, by using the superposition theory of the sheet deformation, the calculation model of the displacement curve of the circular piezoelectric vibrator and the power generation capacity under the concentrated load is established. The results show that the radius ratio, thickness ratio and Young’s modulus of the circular piezoelectric vibrator have greater influence on the power generation capacity. When the material of piezoelectric oscillator is determined, the best radius ratio and thickness ratio make the power generation capacity the largest. Excessive or small radius ratio and thickness ratio will reduce the generating capacity and even generate zero power. In addition, the electromechanical equivalent model is established. Equivalent analysis is made by changing the circuit impedance. The results are consistent with the theoretical simulation results, indicating that the established circuit model can truly reflect the characteristics of the theoretical model. (paper)
[en] This work demonstrates and discusses the fabrication of cross-plane configured micro thermoelectric devices for the power generation and thermal management of the photonic devices. The device is fabricated using a cost-effective electrodeposition technique on the silicon wafer with 210 pairs of the electrodeposited p-type BiTe and n-type CuTe pillars. The complete device is fabricated using the flip-chip bonding technique. Our focus in this work is on the challenges in the device fabrication and the solutions employed to overcome the obstacles thereby successfully fabricating the micro thermoelectric device. (paper)
[en] Hydropower is the world's leading renewable energy resources in electricity generation that produces 71% of electricity more than other forms of energy sources such as coal, gas, and oil which are not reliable and gradually diminish day by day. Therefore, hydropower is essential and considered as an economical factor for producing electricity. There are many untapped hydropower resources in the world. The developing country, Myanmar, is also have about 100 GW unexploited energy potential from the rivers for hydropower electrification. This paper is the review paper which presents about the condition of the hydroelectricity in Myanmar in detail.
[en] Highlights: • This sensor presents 1.33 mV/(m/s2) sensitivity and less than 1% nonlinearity. • The structure and flexible materials contribute to 15,000 g shock resistance. • Overlapping area among triboelectric layers and electrodes minimizes its volume. • Tiny vibration energy can be harvested by this sensor. Traditional MEMS acceleration sensors have been well developed, but most of them require an additional power source to operate. Moreover, they are usually susceptible to limited mechanical shock survivability due to the dominant reliance on rigid materials such as silicon. Recently, with the advancement in flexible materials and nanogenerators, piezoelectric sensors have received increasing interests due to the distinctive property of electricity generation, caused by its structural deformation. In this paper, we demonstrate a novel triboelectric acceleration sensor with flexible structure that is not only self-powered without the need of additional power source, but also is durable in a wide spectrum of operating ranges. The sensitivity is measured to be 1.33 mV/(m/s2) with 0.64% nonlinearity over the acceleration range from 0 to 6 m/s2, and the shock survivability of 15,000 g. We envision that our work provides a new train of thought to combine MEMS technology and flexible electronics for the development of sensors with high shock survivability and low power consumption.
[en] Highlights: • We leverage a state-of-the-art generation adequacy assessment power system model. • The model incorporates probabilistic operating reserve requirements. • The contribution of operating reserves to system adequacy is accurately captured. • The methodology yields more accurate adequacy indices than deterministic studies. • Policy makers should adopt these novel power system models in adequacy assessments. - Abstract: An electricity generation system adequacy assessment aims to generate statistically significant adequacy indicators given projected developments in, i.a., renewable and conventional generation, demand, demand response and energy storage availability. Deterministic unit commitment (DUC) models with exogenous reserve requirements, as often used in today's adequacy studies to represent day-to-day power system operations, do not account for the contribution of operating reserves to the adequacy of the system. Hence, the adequacy metrics obtained from such an analysis represent a worst-case estimate and should be interpreted with care. In this paper, we propose to use a DUC model with a set of state-of-the-art probabilistic reserve constraints (DUC-PR). The performance of the DUC-PR model in the context of adequacy assessments is studied in a numerical case study. The Expected Energy Not Served (EENS) volume obtained with the DUC model is shown to be a poor estimate of the true EENS volume. In contrast, the DUC-PR methodology yields an accurate estimate of the EENS volume without significantly increasing the computational burden. Policy makers should encourage adopting novel operational power system models, such as the DUC-PR model, to accurately estimate the contribution of operating reserves to system adequacy.
[en] In this study, we demonstrate the performance of silicon nanowire (SiNW)n-metal oxide semiconductor (MOS) and p-MOS ratioed inverters that are fabricated on bendable substrates. The electrical characteristics of the fabricateddevices can be controlled by adjusting the load voltage. The logic swings of then- and p-MOS ratioed inverters at a low supply voltage of 1 V are 80% and 96%, respectively. The output voltage level of the p-MOS ratioed inverter is close to rail-to-rail operation. The device also exhibits stable characteristics with goodfatigue properties. Our bendable SiNW ratioed inverters show promise asa candidate building block for future bendable electronics. .
[en] MNiSn (M = Hf, Zr, Ti) -based half Heusler compounds have attracted extensive attention as promising materials in thermoelectric power generation. In this work, the thermoelectric properties of the cheapest composition TiNiSn from this system are investigated. Isoelectronic substitutions of Si and Ge on Sn site are employed to reduce the lattice thermal conductivity. It is found that Si substitution leads to simultaneously enhanced mass and strain field fluctuations in TiNiSn, while the strain field fluctuation dominates the decrease of thermal conductivity in Ge substituted TiNiSn. A maximum ZT of 0.48 at 740 K is obtained in , which is a 23% increase compared to TiNiSn. This result highlights the role of strain field fluctuation in suppressing lattice thermal conductivity and improving the thermoelectric performance of half-Heusler compounds. (paper)
[en] The paper describes an iterative three-step approach to the optimization of cost and size in competitive power markets. In 2000 I analysed modular and small reactor economics, where the real issue is meeting power and financial market requirements, not technology choice. To ensure the plant cost intersects the market generating price, multiple units or “modules” include mass production with learning effects, utilize the “saw-tooth” cash flow curve, require an “order book” for 10-100 standardized units, and investment in module “factories”. Moreover, worldwide the fractional market share is partly determined by the price advantage over local alternate fuels. Entirely new products must be developed because low capital cost and high efficiency, modern natural gas and supercritical coal plants likely dominate for the next 20 years. There is time for non-conventional and innovative technology developments to challenge the paradigms of the past that cannot meet the required future market competitiveness. (author)