In early spring or winter, supercooled raindrops impact on transmission lines and accumulate ice on its surface frequently, which may induce galloping vibration occurs. Studies on collision ...coefficient or icing mostly focus on key parameters of wind velocities, raindrop sizes and conductor diameters, whereas few involve electric field. In order to clarify the influence of the direct current electric field on the collision coefficient of transmission lines, a calculation formula of the mass flow rate of raindrops was proposed, and the process of raindrops hitting the conductor surface is numerically calculated by the Euler–Lagrange method. The effects of electric field intensity, conductor diameter, cross‐sectional shape, wind velocity, raindrop diameter and charge density on the collision coefficient of transmission lines are analyzed. The results show that the collision coefficient decreases with the increase of electric intensity. As the electric intensity increases from 0 to 66.7 kV/cm, the collision coefficient decreases about 33%. Because of the repulsion between the conductor and raindrops, more raindrops move away from the conductor surface and collision coefficient decreases. The collision coefficient of the actual conductor under no electric field is slightly smaller than that of the simplified circular cross‐section. Under DC electric field, the collision coefficient of the conductor decreases with wind velocity increase up to 8 m/s. Beyond that threshold, the collision coefficient is almost constant.
This study proposes a calculation formula of the mass flow rate of raindrops, and the proces of raindrops hitting the conductor surface is numerically calculated by Euler‐Lagrange method. The effects of electric field intensity, conductor diameter, cross‐sectional shape, wind velocity, raindrop diameter and charge density on the collision coefficient of transmission lines are analyzed.
The approximating sequence Riccati equation method is an efficient approach for solving the nonlinear optimal control problems, but its neglect of nonlinear dynamics and necessary optimality ...condition makes the control law difficult to satisfy the optimality. In this paper, an approximating pseudospectral method with state‐dependent coefficient optimization algorithm is proposed to solve this defect. By introducing the approximating pseudospectral method, the original nonlinear problem is transformed into a sequence of linear subproblems, which preserves the nonlinearity of solution. Then a state‐dependent coefficient optimization algorithm based on the gradient projection technique is proposed, which ensures the optimality of the control law. A double‐layer optimization structure is designed to facilitate the coordination between the approximating method and the optimization algorithm. Theoretical analysis proves the convergence of the proposed method. Comparative case studies illustrate the effectiveness in reducing the performance index and ensuring the optimality of the control law.
A nonlinear optimal control problem is reduced to a sequence of timevarying linear quadratic optimal control subproblems. By using the approximating pseudospectral method, an numerical solution to the optimal control problem can be obtained. Convergence of the algorithm is also proved.
A general strategy for the cleavage and amination of C−C bonds of cycloalkanols has been achieved through visible‐light‐induced photoredox catalysis utilizing a cerium(III) chloride complex. This ...operationally simple methodology has been successfully applied to a wide array of unstrained cyclic alcohols, and represents the first example of catalytic C−C bond cleavage and functionalization of unstrained secondary cycloalkanols.
Breaking (D)BAD: A general strategy for the cleavage and amination of C−C bonds of cycloalkanols has been achieved through visible‐light‐induced photoredox catalysis utilizing a cerium(III) chloride complex. This method represents the first example of catalytic C−C bond cleavage and functionalization of unstrained secondary cycloalkanols. DBAD=di‐tert‐butyl azodicarboxylate, Boc=tert‐butoxycarbonyl.
Screening novel narrow-band phosphors inspired by natural mineral structures is urgently demanded for improving the performance of phosphor-converted light-emitting diodes. In this work, a novel ...narrow-band deep-blue-emitting tungsten bronze-type KCaAl
F
:Eu
phosphor with superior thermal stability is successfully synthesized. Structural analysis shows that the representative KCaAl
F
:0.013Eu
phosphor crystallizes in an orthorhombic space group
222
with a rigid network. The rigid AlF
octahedrons are linked together by sharing corners to build endless AlF
chains, further stacking with each other in a highly cross-linked way to establish the rigid network of the KCaAl
F
host. Benefiting from the rigid microenvironment, the developed phosphor not only shows a narrow-band deep-blue emission with a full width at half maximum of 45 nm and a high color purity of 92%, but it also exhibits the superior thermal stability with an emission loss of only 10% at 423 K, demonstrating its application potential in bridging the deep-blue spectral cavity toward sunlight-like full-spectrum lighting. In addition, the concentration/temperature quenching behaviors of KCaAl
F
:Eu
phosphor are systematically investigated. By revealing the specific structure-property relationship of tungsten bronze-type KCaAl
F
:Eu
phosphor, the present study provides a significant guide for identifying the novel narrow-band deep-blue-emitting component applicable to full-spectrum warm white light-emitting diode devices.
Porous structures are widely used in medical implant, aerospace and other light-weight manufacturing fields. The research on processability and fabricating process are of great importance to laser ...addictive manufacturing of porous structure, therefore formulating several rules for SLM fabrication of porous structure is necessary. This article had studied the designing rules and the key points to fabricate the porous structure precisely based on selective laser melting (SLM). In order to obtain the fabricating effect of the pre-designed porous structure, besides optimizing fabricating process, there are still a few problems to be solved gradually, including the critical inclined angle, the fabricating resolution, powder adhesion, designing unit cell and porous structure that fit for SLM process. Through the experiments of fabricating overhanging structures with different inclined angles, the critical inclined angle for designing the porous structure was got. Through designing the thin walls and cylinders with different geometrical dimensions, the SLM fabricating resolution is obtained. Then, based on the critical inclined angle and the geometrical resolution, the octahedral unit cell structure and corresponding design rules that fitted for SLM process were proposed. At last, the experiment of fabricating porous structure was conducted and the pore's sizes were also measured. The results proved that the porous structure can be well fabricated by SLM. This study provides theoretical basis for designing and manufacturing of controllable porous structure based on SLM technique.
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•Ginsenosides have a great potential in Mets and CVDs treatment.•This review comprehensively clarifies the molecular mechanism in the treatment of ginsenosides on Mets and CVDs.•This ...review summarizes the clinic trials of ginsenosides on Mets and CVDs.•This review prospects the future development direction of ginsenosides.
Epidemiological studies showed that the metabolic syndromes (MetS) and cardiovascular diseases (CVDs) are responsible for a serious threat to human health worldwide. MetS is a syndromes characterized by fat metabolism disorder, obesity, diabetes, insulin resistance and other risk factors, which increases the risk of CVDs initiation and development. Although certain drugs play a role in lowering blood sugar and lipid, some side effects also occur. Considering the multiple pathogenesis, a great deal of natural products have been attempted to treat metabolic syndromes. Ginsenosides, as the active components isolated from Panax ginseng C.A.Mey, have been reported to have therapeutic effects on MetS and CVDs, of which pharmacological mechanisms were further studied as well. This review aims to systematically summarize current pharmacological effects of ginsenosides on MetS and CVDs, potential mechanisms and clinic trials, which will greatly contribute to the development of potential agents for related disease treatment.
Afforestation and reforestation are pivotal in mitigating land degradation and bolstering the carbon sink capacity of terrestrial ecosystems. However, the potential economic ramifications of ...afforestation and reforestation in the context of climate change remain largely unexplored. In this study, we employed an interdisciplinary methodology to establish a framework for assessing future forest potential and carbon sequestration in the Eastern Loess Plateau region of China. Our findings indicate that an estimated 17,392.99 km2 of land suitable for afforestation still existed within the region, exhibiting a propensity to aggregate around existing forests rather than being dispersed randomly. Notably, 4385.36 km2 was prioritized for afforestation initiatives. Projections suggest a significant enhancement of the forest carbon sink within the study area by 2050, ranging from 36.93 Mt to 105.38 Mt. The corresponding economic value for this enhancement is estimated to vary between US$3.25 billion and US$17.68 billion. Of significance is the observed polarization of the region's carbon sink capacity over time, with half of the total carbon sinks concentrated within 10% of the districts. Additionally, approximately 26% of the counties are expected to transition from carbon sinks to carbon sources. These findings underscore the substantial impact of climate change on forest distribution and suggest a targeted approach to combat forest degradation by circumventing ineffective afforestation activities.
•Identifies priority areas for afforestation in the context of future climate change.•Assessed the potential for regional forest carbon sink growth.•The economic value of forest carbon sinks was estimated taking into account the discount rate.
► Use selective laser melting to make Ti6Al4V porous structure. ► Build simplified model of porous structure, calculate maximum bearing capacity. ► Get the fracture load of porous structure with ...compression test. ► Analyze relation between theoretical maximum bearing capacity and fracture load. ► Analyze the cause of porous structure fracture.
This paper designs one octahedral Ti6Al4V porous structure and then establishes a simplified model. The Ti6Al4V porous structure is manufactured by selective laser melting. Its experimental and theoretical fracture loads are obtained through theoretical calculation and compression test respectively. The result demonstrates that there is an exponential relationship between the experimental fracture load and the porosity of the porous structure. With an average relative error of 5.86%, the deviation between experimental and theoretical fracture load is small, which indicates that the predication accuracy is comparatively high. So the fracture load calculation theory is valuable in practical applications. Finally, the fracture analysis indicates that fractures of units and porous structures are brittle fractures, which belong to cleavage fracture.
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•We identified priority areas for afforestation on the Loess Plateau.•The Loess Plateau is not suitable for large-scale afforestation.•The suitable afforestation areas are mainly ...concentrated in the east and the south.•Forested lands in the southeastern Loess Plateau are at risk of degradation.
China has led global greening processes over recent decades, however, a series of negative impacts have inevitably emerged in some areas, especially on the Loess Plateau. While the potential for afforestation of the Loess Plateau has been identified, the micro-regions where afforestation should be prioritized have yet to be identified. We constructed a framework for identification of land suitable for forest on the Loess Plateau. By simulating land-use changes on the Loess Plateau under various development scenarios for the period from 2020 to 2030, we identified land that is suitable for afforestation and explored the trends and spatial distribution of different forest stands. The results show that only ∼ 40 km2 on the Loess Plateau is suitable for forest growth by 2030, mainly in the eastern region, with the southeastern part of the Loess Plateau at greater risk of degradation. The suitable land for forest growth is fragmented. Under the current climate conditions and policy background, we believe there is limited opportunity for large-scale conversion of farmland to forest on the Loess Plateau; however, if the afforestation areas are scientifically planned, it is feasible to achieve greening in local areas. Grasslands may be a more suitable primary approach to ecological restoration in the Loess Plateau region. The results will help guide more efficient and sustainable afforestation projects in the Loess Plateau region.
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•Ultrasound and microwave decreased the fluidity of immobilized water and free water.•Ultrasound and microwave reduced the particle size of MP and decreased the solubility.•Ultrasound ...and microwave promoted the unfolding of α-helix structures of MP.•Ultrasound and microwave facilitated the formation of more compact microstructures.•Ultrasound–microwave combination treatment has synergistic effect.
The objective of this study was to evaluate the effects of single ultrasound (360 W, 20 min), single microwave (10 W/g, 120 s) and ultrasonic–microwave combination treatment on shrimp surimi gel properties. The structure and physicochemical properties of myofibrillar protein (MP) were also determined. Low-field nuclear magnetic resonance showed that the fluidity of water molecules and the moisture content decreased, the stability and water holding capacity (WHC) increased after single ultrasound, single microwave and ultrasonic–microwave combination treatment. Compared with the traditional water bath treatment, ultrasound and microwave treatment reduced the total sulfhydryl content and promoted the formation of intermolecular disulfide bonds and hydrophobic interactions, which improved the compactness of the network structure of shrimp surimi gel. Moreover, Fourier transform infrared spectroscopy and sodium dodecyl sulfate–polyacrylamide gel electrophoresis analysis revealed that these treatments not only inhibited the degradation of MP, but also decreased the α-helix content and increased the β-sheet content. The three treatments also significantly reduced the particle size and decreased the solubility of MP. Overall, the effect of ultrasonic–microwave combination treatment was superior to that of either single treatment.
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