Efficient cooling of electronic devices is critical for ensuring stable performance, extending service life, and enhancing reliability. This capability is essential for advancing high-power-density and integration technologies, mitigating thermal failure risks, and improving energy efficiency. However, existing miniaturized ionic wind radiators face limitations in both research depth and spatial coupling between corona wind modes and heat load distributions. To address these challenges, this study integrates corona discharge with a heat sink, proposing a novel coreless monolithic corona wind heat sink (CM-CWHS) for electronic cooling. An unsteady electric fieldflow coupling model is developed to characterize complex inter-fin flow dynamics. Key parameters-including operating voltage, discharge distance, emitter longitudinal height, collector width, and fixing plate positionare analyzed via a response surface model. Through multiple regression, a predictive model for the flow enhancement coefficient is established, quantifying the relationship between structural parameters and cooling performance. A four-factor, three-level Box-Behnken experimental design reveals the relative contributions of each parameter to flow enhancement. A composite main-auxiliary fin structure (30 degrees main fin angle, 15-mm auxiliary fin length) is proposed, achieving a flow enhancement coefficient of 247.25 x 10-6 m3/J and a Nusselt number of 46.44-representing improvements of 37.2 % and 46.6 %, respectively, over the baseline design. Flow distribution analysis demonstrates that optimized wall pressure gradients reduce ineffective ionization regions, resulting in a centrosymmetric divergent corona wind pattern between main fins, with maximum velocity gradients aligned spatially with heat source locations. Compared to conventional aluminum substrate heat sinks, the optimized CM-CWHS reduces temperature by 17.9 degrees C under a 15.5-W heat load, improves cooling capacity by 19.51 %, and achieves a convective heat transfer coefficient of 43 W/(m2 & sdot;K) (a 16.1 % increase). This work offers a viable solution to the conflict between electronic miniaturization and high heat flux density.

This paper presents comprehensive and rigorous mathematical formulations for the graph heat kernel, tailored for smooth propagation in semi-supervised graph-based learning. Leveraging the inherent strengths of heat kernels, we address the challenge of over-smoothing by adopting their most natural analytical form. A precise transformation of the normalized Laplacian is proposed to map its spectrum from the shifted interval [0, 1] into the Chebyshev polynomial range [-1, 1]. This exact rescaling distinguishes our approach from earlier works, enabling more stable and accurate computations. By preserving the temporal dynamics of the propagation process, the method substantially mitigates over-smoothing, leading to improved learning performance. We emphasize that the normalized Laplacian, inherently a band-pass filter, must be carefully adjusted to the Chebyshev range for optimal efficiency and accuracy. The proposed conversion procedure ensures effective spectral alignment, significantly enhancing the performance of semi-supervised graph-based learning.

The escalating demand for miniaturized and high-performance electronic devices has led to a substantial surge in the heat generation rate, which poses a significant threat to the stability and reliability of electronic components. Conventional cooling technologies are now confronted with formidable challenges. In this study, an ionic wind heat sink (IWHS) was developed by positioning wire electrodes parallel to the fin channels. The key innovation lies in the strategic rearrangement of the emitters, which effectively modifies the flow distribution of the mixed flow, thereby enhancing the cooling efficiency. A comprehensive approach integrating experimental investigations and numerical simulations was adopted. Regarding material selection, the results indicate that it exerts a substantial impact on both the cooling performance and the heat transfer efficiency per unit mass of the IWHS. The primary structural parameters of the IWHS play a crucial role in determining its cooling capacity and the flow distribution of the mixed flow. The discharge gap affects the gas flow intensity through two main mechanisms. It weakens the body force acting on charged particles. It reduces the mean electric field intensity around the wire electrodes, leading to a decrease in the gas flow intensity. The flow speed drops due to wall friction within the fin channels and the loss of acceleration downstream. The combination of ionic wind and low-velocity incoming flow can remarkably increase the heat transfer coefficient and reduce the thermal resistance. The parallel side-placement design cuts down the momentum loss by 28%. The insulation wall isolation technology suppresses 93% of the potential interference between electrodes. This design offers a novel thermal management solution for micro-electronic devices, enabling a 40% reduction in volume and a three-fold increase in the energy efficiency ratio.

The development of heterogeneous nanocatalysts with high performance is essential for improving hydrogen production through formic acid dehydrogenation, but challenging. Herein, highly dispersed Pd nanoparticles (NPs) were successfully immobilized on porous nitrogen-doped carbon cages (PNCCs) derived from zeolitic imidazole frameworks. By virtue of the synergistic effect, the optimized Pd/PNCC nanocatalytic systems exhibit an excellent catalytic kinetics toward catalyzing FA dehydrogenation with a turnover frequency (TOF) value as high as 3174 h−1 at 323 K, which is 59 times relative to that of Pd nanoparticles. The exceptional activity may be ascribed to the PNCC solid support may induce a strong electronic metal–support interaction to optimize the electron configuration of Pd active sites and accelerate the kinetics of O-H bond cleavage, resulting in an enhanced catalytic performance toward FA dehydrogenation. This work will supply a novel strategy for the development of supported nanocatalysts with high performance for tremendous catalytic applications in the future.

In order to improve the thermal management performance of lithium-ion batteries at different ambient temperatures (Tamb), a battery thermal management system coupling dual-layer phase change materials (PCM) with liquid cooling was proposed. The inner layer adopted high-thermal-conductivity composite phase change materials (CPCM), while the outer layer consisted of PCMs with different phase change temperatures. The experiment results showed that, in comparison to the single-layer design, the dual-layer PCMs achieved highly efficient temperature control under various Tamb conditions while reducing the maximum temperature (Tmax) and the maximum temperature difference (Delta Tmax) of the battery. Among the three structural designs, the dual-layer arrangement composed of CPCM-44 and RT44HC (Case 3) exhibited the best temperature control performance. Under low-temperature condition (5 degrees C), the combination of Scheme 5 (CPCM-35/RT28HC) exhibited the best performance. The maximum temperature difference Delta Tmax was controlled within 2.1 degrees C, and the heat preservation time was extended to 69 min. Under high-temperature conditions (40 degrees C and 50 degrees C), the combination of Scheme 7 (CPCM-35/RT44HC) had the best temperature control effect. The temperature rise time was extended to 143 min and 273 min, respectively, and Delta Tmax remained within 5 degrees C.

Commutation failure in high voltage direct current (HVDC) transmission is commonly attributed to disturbances in the inverter-side AC system or to converter-valve malfunctions. However, engineering practices show that faults in the sending-end AC network may likewise trigger commutation failure at the inverter. To address this issue, a fault location scheme of HVDC rectifier station based on the temporal feature of AC current state integral is proposed. Firstly, the fault characteristics of internal and external faults are analyzed, and it is found that when the fault occurs within the rectifier station, it leads to a significant reduction in the state temporal feature of the commutation valve group compared to the normal temporal feature, while the fault occurs outside of the rectifier station, the change in the state temporal feature of the commutation valve group remains within a small threshold compared to the normal temporal feature. Secondly, exploiting the differences in temporal feature of AC current state integral between internal and external faults, both types of faults can be accurately identified. Finally, the simulation results confirm that the proposed fault location scheme effectively differentiates between internal and external faults. It achieves an identification accuracy of over 97

Particulate matter (PM) has serious hazards to the ecological environment and human health. The development of green and sustainable technologies for efficient removal of PM has become an urgent need in the field of environmental engineering. In this study, a non-thermal plasma (NTP) online oxidation decomposition experimental system for PM was established to explore the effects of NTP on the microstructure, oxidation characteristics and carbon and oxygen element composition of PM under different loads (25 %, 50 %, 75 %, and 100 %), and to clarify the effect of exhaust temperature that changes with load on the oxidation and decomposition of PM. The results show that NTP significantly weakened the aggregation degree of PM particles, the proportion of short crystallites (<1 nm) at each load increased significantly, the proportion of small crystallite spacing (<1 nm) increased significantly, and the crystallite curvature decreased significantly at low load. NTP treatment improves the PM graphitization degree, increases crystallite defects, and produces more amorphous carbon. The ignition temperature Ts, burnout temperature Te and maximum oxidation rate temperature Tmax of element carbon (EC) tend to shift to lower temperatures, the oxidation temperature of PM decreases, and the oxidation activity increases. The carbon particle microcrystals contain a large amount of C element. After the microcrystals are cracked, O atoms are continuously typed into the carbon particles, C-C transforms into C-O, the relative content of C element decreases, and C-O is transformed into C--O after NTP oxidation. The treatment process of NTP oxidation of PM is fastest at 75 % load due to the moderate treatment temperature range. The research results can provide an online and efficient PM degradation solution for diesel engine exhaust treatment, which has important theoretical value and engineering significance for the purification of atmospheric PM.

Efficient heat dissipation methods have been the focus of battery thermal management research. Due to the limitations of flow and heat transfer in traditional straight channel cold plates (SCCP), this paper introduces a ring channel cold plate (RCCP) and utilizes the j/f factor to evaluate the comprehensive thermal performance of the cold plates. Through comparison and analysis, it is found that the RCCP has a lower pressure drop and better comprehensive thermal performance. As the mass flow rate increases, the j/f improvement effect of the RCCP becomes more pronounced. Additionally, when the branch channel width is 6 mm, the RCCP exhibits higher comprehensive thermal performance. However, in the RCCP of equal width, the innermost channels have the shortest flow path and the largest flow rate. To further enhance heat transfer, the influence of non-uniform structure on the performance of RCCP is investigated. The result shows that the narrow inside and wide outside channel arrangement can enhance the heat transfer performance of the RCCP but at the cost of increasing pressure drop. Among them, the outermost, middle, and innermost channel widths of 6.66 mm, 6 mm, and 4 mm, the cold plate has better comprehensive thermal performance, more suitable for battery thermal management. The RCCP with a narrow inside and wide outside provides a new option for more efficient battery thermal management.

The aging deactivation of noble metal catalysts is a critical challenge for diesel oxidation catalysts (DOC). This study investigated the regeneration of aging DOC using non-thermal plasma (NTP) technology. Combined with catalytic oxidation performance testing of platinum (Pt) catalysts on DOC and analyses through EDS, BET, O2TPD, TEM, and XPS, the effects of NTP regeneration were evaluated. NTP effectively degraded carbon deposits within the DOC at temperatures below 210 degrees C, lower than the DOC's maximum operating temperature and the Pt catalyst's deactivation temperature. During regeneration, BET area increased by 39.06 %, average particle size decreased by 28.5 %, relative carbon content in the Pt catalyst dropped by 60.9 %, and relative oxygen content increased. NTP promoted deep oxidation of Pt, forming oxide layers of PtO (0.22 nm) and PtO2 (0.11 nm), which enhanced catalytic efficiency for CO oxidation. NTP successfully regenerated DOC, restored performance lost due to aging deactivation, and improved the low-temperature activity, stability, and high-temperature resistance of Pt catalysts.

Particulate matter (PM) is harmful to the environment and human health. It is of practical significance to explore green and sustainable technologies for efficient removal of PM by studying the mechanism of PM oxidation and decomposition. A visualization test system for oxidatively decomposing diesel PM using non-thermal plasma (NTP) was developed to perform oxidative decomposition tests on PM samples at different lengths of time at 120 degrees C. The physical and chemical properties of primary particles, elemental carbon (EC) oxidation activity, and surface functional groups of the PM at different oxidation stages were analyzed to investigate how micronanostructure changes of PM affected the oxidation characteristics and elemental occurrence. The structure of primary particles was divided into three parts: in-core, ex-core, and ex-core edge. A dynamic nanostructure model of primary particles was established during the reaction process. The primary particles experienced the evolution process of 'massive removal of crystalline at the outer edge of the nucleus', 'disordered arrangement of crystalline' and 'hollow crystalline in the nucleus after erosion ', corresponding to the early, middle and late stages of oxidation, respectively. The nanostructure properties of PM changed non-linearly during the decomposition of PM by NTP, and there was a linkage effect among the microcrystalline parameters, oxidation activity, and elemental distribution of PM.

Phase change material (PCM) has been widely used for the thermal management of electronic devices due to its high latent heat and the ability to maintain constant temperature during phase change. However, traditional PCM based thermal management devices face some issues such as PCM leakage and corrosion, separating PCM from the electronic device has the potential to address this issue. In the paper, a novel HS-PCM module in which the electronic device does not directly contact with PCM is numerically simulated, some factors affecting the electronic device temperature are discussed such as copper rods number, copper plate height, and PCM property. The results indicate that increasing the copper rods number can effectively lower the electronic device temperature while inevitably reducing the PCM mass which also shortens the effective temperature control time of the HS-PCM module, the number of 24 copper rods is appropriate. It is found that the electronic device temperature has no apparent difference when copper rods are replaced with a copper plate keeping the same volume which can give guidance for actual applications. Another PCM with lower melting point is introduced into the HS-PCM module and isolated from the original PCM by the copper plate, it is proved that the electronic chipboard temperature furtherly reduces when the PCM with a lower melting point is placed above the copper plate comparing with under the copper plate.

Heat exchangers play a major role in reducing emissions and conserving energy. There is a plethora of theoretical research on the enhancement of heat transfer caused by ionic wind, but there is still a lack of studies on the practical application of ionic wind in heat exchangers to increase heat exchange capacity. This work developed an original ionic wind heat exchanger with a dividing wall. It may be applied to difficult circumstances when conventional heat exchangers fail for air-to-air heat exchange. The study conducted experiments to investigate the impact of many factors, including intake air velocity, discharge spacing, and electrode distribution scheme, on the ionic wind intensity and the heat exchanger's increased heat transfer coefficient. A two-dimensional model was used to analyze the internal flow and thermal properties of the heat exchangers with wire emitters. By combining active and passive heat exchange technologies, an ionic wind heat exchanger with serrated grounded electrodes was presented. The outcomes demonstrated that a suitable intake air velocity enhances the heat exchanger's capacity for heat exchange. The improved heat exchange effect of ionic wind is more important when the inlet wind speed is less than 1 m/s. When the intake air velocity approaches 1.3 m/s, the ionic wind has less of an impact on the heat exchanger's capacity for heat exchange. The benefits of improved heat transfer are promoted by placing the emitter closer to the channel entry. Increasing the operating voltage further enhances the heat transfer enhancement ratio (HTER). The number and arrangement of wire electrodes should be chosen with consideration for the 'barrier effect' between neighboring emitters and the distance from the entrance when utilizing multiple wire electrodes. In comparison to the three-wire and five-wire electrodes, the four-wire electrode heat exchanger's HTER values were increased by 5.9 % and 14.3 %, respectively. The ionic wind heat exchanger's capacity for heat transfer is further increased using a zigzag grounding electrode. The zigzag uses a decreased aspect ratio, and the emitter is positioned slightly above the tip, improving the system's heat transfer capabilities. When compared to a heat exchanger with a flat plate grounded electrode, the four-wire electrode heat exchanger produced a 158 % increase in HTER value.

This study is to utilize the heat-absorbing and releasing capabilities of phase change materials (PCM) to regulate the surface temperature fluctuations of batteries during charging and discharging. The goal is to keep the battery within the optimal operating temperature range. The impact of PCM thickness and phase change temperature on battery temperature is investigated by encircling a cylindrical battery with a PCM ring. To improve the thermal conductivity of PCM, expanded graphite (EG) is added to make a composite phase change material (CPCM), and the effects of various EG mass ratios on battery surface temperature and CPCM utilization level are investigated. The findings indicate that increasing PCM thickness effectively extends temperature control time, but its impact is limited. The difference in phase change temperature of PCM controls the battery temperature in different temperature ranges. Lower phase change temperatures are unsuitable for controlling battery temperature in high temperature environments. The addition of EG enhances the thermal conductivity of PCM, leading to further control of battery temperature. The results show that the addition of 6% (mass ratio) EG to CPCM extends the effective temperature control time by 11 min and improves by 28% compared to a single PCM. The CPCM utilization is also more satisfactory and achieved a balance between heat storage and thermal conductivity in a battery thermal management system (BTMS) based on PCM.

The development of pH -universal HER electrocatalyst with Pt -like activity remains challenged yet critical for hydrogen energy systems. Herein, we have successfully immobilized RuO x nanoparticles on the surface of C-N derived from zeolitic imidazolate frameworks (RuO x @C-N). The obtained RuO x @C-N exhibits Pt -like HER performance with overpotential of as low as 14 and 93 mV to drive the current density of -10 and -100 mA cm -2 in 1.0 M KOH, respectively. Furthermore, RuO x @C-N exhibits an unexpected mass activity of 0.81 A cm -2 mg RuOx -1 , structure, which will facilitate the electron transfer due to the Mott -Schottky effect. Additionally, the nitrogendoped carbon framework will efficiently adjust the electronic structure of metallic catalytic sites and optimize the kinetics of catalytic reaction. Benefiting from the Mott -Schottky effect, the RuO x @C-N electrocatalysts exhibit pH -universal catalytic performance toward hydrogen evolution in various electrolytes, corroborating its university and facility in industrial hydrogen production. This approach offers a facile and versatile strategy for the development of Ru-based electrocatalysts with high performance and robust stability. which is even superior to benchmark Pt/C. Such an improvement is attributed to RuO x @C-N hetero

Phase Change Material (PCM) is widely applied in the thermal management due to its high latent heat, but lower thermal conductivity limits its further development. As a kind of high thermal conductivity additive, the copper foam is commonly mixed into PCM to prompt the thermal conduction ability. To reduce the influence of copper foam on the latent heat, the partial filling schemes have been concerned and used in recent years. This research presents the influence of partial filling of copper foam on the internal temperature distribution of PCM. An experimental platform is constructed to investigate and analyze the melting process and temperature distributions of PCM in detail. The results show that the maximum temperature difference in PCM decreases with the increase of the filling ratio, and reaches minimum when the pore density of copper foam is 20PPI (pore per inch). Moreover, the copper foam achieves optimal temperature difference control performance when it positioned in close to the heat source. It is also found that these partial filling schemes still have ability to control the PCM's internal temperature distribution in the condition of fluctuating heat source. This study provides a guidance on partial filling copper foam in PCM for the thermal management.

In order to ensure the safety and stability of the cooling system during the operation of the battery thermal management system combined with composite phase change material cooling and liquid cooling, it is usually necessary to continuously pump cooling water. It inevitably caused that the latent heat of composite phase change material could not be fully released and extra pump power was consumed. In the study, five different energy saving strategies were proposed and the energy efficiency ratio was defined to evaluate their cooling effects and energy saving. The effect of energy saving strategies on energy consumption of liquid cooling and latent heat utilization of composite phase change material was analyzed. The results show that III and V can meet their cooling requirements and have a high energy efficiency ratio. The screw pitch and cooling water flow rate in these two modes were investigated. The results show that the increase in screw pitch reduces the heat transfer efficiency, resulting in an increase in Tmax and ΔTmax, and ΔTmax exceeding the maximum range. Diminishing the cooling water flow will precipitate a rise in battery temperature, enabling the CPCM to operate at its maximum capacity and consequently decreasing ΔTmax. As a cooling water flow of 20 ml/minute in III and V all can satisfy the cooling requirements. Additionally, the III was also competent when the cooling water temperature was raised from 25 °C to 35 °C.

Abstract A new kind of ionic wind blower that employs auxiliary electrodes to boost the ionic wind velocity and enhance the cooling efficiency is developed to address the issue of heat dissipation in electronic devices with high heat flux densities. The ‘wire-mesh-auxiliary electrode’ and ‘needle-mesh-auxiliary electrode’ blowers have been designed. An emitter, a collector, and two auxiliary electrodes make up each structure. Before determining the optimum operational voltages for the auxiliary electrode under the two configurations, experiments are carried out to confirm the secondary acceleration effect of the auxiliary electrodes. The effects of the auxiliary electrode's spacing and the voltage polarity supplied to the emitting electrode and auxiliary electrodes on the produced ionic wind velocity are investigated once the working voltage has been determined. Finally, a simulation computation is implemented to look into the ionic wind flow distribution in the ‘needle-mesh-auxiliary electrode’ blower. The findings indicate that in terms of voltage endurance operating range and maximum output ionic wind velocity, the ‘needle-mesh-auxiliary electrode’ blower outperforms the ‘wire-mesh-auxiliary electrode’ blower. The system's output ionic wind velocity is greater when negative high voltage is supplied to the emitting electrode and positive high power is applied to the auxiliary electrode. Following the use of auxiliary electrodes, a considerable amount of electrons condense in the central area between the two auxiliary electrodes, creating an ion jet downstream. The output velocity of the ionic wind is greater, and the flow is more concentrated. Some electrons in the mainstream produce the reverse ionic wind under the influence of the electric field downstream of the auxiliary electrodes, which disrupts and deflects the mainstream's velocity.

Solid-state fans (SSFs) have distinct advantages over traditional cooling fans in the thermal management of high-power electronics. In this work, a magnetic-field-enhanced SSF is proposed, and the physical model of negative corona discharge superimposed by an electromagnetic field is established. A computational model is used to calculate and analyze the effect of the magnetic field on the ionic wind distribution. The magnetic flux density and permanent magnet position distribution in the SSF are optimized experimentally, and the optimized SSF is applied to LED chip cooling. The findings show that adding a magnetic field encourages electrons to collide with neutral gas molecules and enhances the driving force of charged particles. The ionic wind velocity and mean driving force at the SSF's outlet will grow as magnetic flux density rises, and the ionic wind flow distribution will show apparent divergence. When the permanent magnet spacing is 15 mm, the highest ionic wind velocity is 2.82 m/s, and the mean driving force of SSF increases by 30.2%. The magnetic-field-enhanced SSF has a better LED-chip cooling effect, the maximum junction temperature drop is 11.6°C, and the cooling efficiency is higher. This research introduces a novel way of improving the cooling of electronics.