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The emergence of many efficient optical field modulation methods and planar optical devices is attributed to the continuous research of geometric phase. Nevertheless, conjugate symmetry of the geometric phase limits the multiplexing of metasurfaces. To overcome this limitation, integrating the propagation phase and the geometric phase to achieve self-decouped metasurfaces can effectively double channel capacity. Herein, a more in-depth derivation of Jones matrices is conducted, leveraging two degrees of freedom offered by the propagation phase and the geometric phase. This approach enables complete modulation in circular polarization channels. By designing the phase difference between a fast axis and a slow axis, energy allocation between different channels can be controlled. It means independent complex amplitude modulation is achieved. On this basis, the geometric phase is introduced to realize tri-channel multiplexing metasurfaces. To verify the feasibility of this method, two metasurfaces are designed, including a bifocal metasurface with adjustable energy allocation and a tri-channel multiplexing metasurface. The proposed multifunctional metasurface offers new insights into wavefront multiplexing for communication systems. [ABSTRACT FROM AUTHOR]

Metasurface holography is a significant technology for the development of ultrathin optical devices. Multichannel holography has received close attention due to its applications in increasing information capacity and optical secret sharing. However, existing design methods for multichannel holography mainly focus on interleaved metasurface imaging in the vertical direction, which will inevitably suffer from the unexpected crosstalk affecting imaging quality. This work presents noninterleaved spin-selective metasurfaces by combining the geometric phase and the propagating phase. It can achieve independent phase control on two orthogonal circular polarizations and image at the desired angle. As a proof-of-concept, two broadband plasmonic metasurfaces are designed for multichannel holographic imaging in the near-infrared band (800–1200 nm). When two orthogonal circularly polarized waves are normally incident, the first plasmonic metasurface displays two different holograms in the vertical direction, thus achieving dual-channel imaging, and the second plasmonic metasurface can make two holograms deflected to the desired angle. It means that these two holograms can be displayed without overlapping for a linearly polarized wave, and the orientable three-channel holographic imaging is realized. Our work provides a general and compact scheme for multichannel orientable holographic imaging. [ABSTRACT FROM AUTHOR]

The urban heat island effect poses a growing threat to human society, especially in densely populated and developed megacities. With the introduction of the Local Climate Zones (LCZ) framework, new perspectives and findings have been brought to urban heat island studies. This study investigated the cooling effect of vegetation and albedo on the surface urban heat island (SUHI) in the classification system of LCZ during different seasons, using three Chinese megacities as case study areas. Single-factor linear regression and Pearson's correlation coefficient were applied to analyze the seasonal cooling effect of both albedo and the NDVI on the SUHI within different LCZs. The results show that (1) the variability of the SUHI is reflected in its dominance and intensity within certain LCZs in different cities and in the efficiency of cooling factors; (2) the cooling effect of vegetation is dominant in each season, and the cooling effect produced by albedo within specific seasons can be differentiated by LCZs. This study provides valuable information for the mitigation of the SUHI magnitude in specific regions and at specific times of the year. [ABSTRACT FROM AUTHOR]

The quantitative realtime polymerase chain reaction (RT-qPCR) is a powerful and sensitive method to measure expression of targeted gene but it highly relies on the use of suitable reference genes for data normalization. We evaluated the expressions of 8 housekeeping genes: 18S ribosomal rDNA (18S rDNA), 28S ribosomal rDNA (28S rDNA),rubisco large subunit (rbc-L), β-actin (ACT), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), elongation factor 1 (EF1), β-tubulin (TubB), and P-phycoerythrin B (PEB), to select the suitable reference genes for different life-history stages (tetrasporophyte, carposporophyte, and male/female gametophyte) of Gracilaria vermiculophylla by absolute quantitative method. Softwares geNorm and BestKeeper were used to verify the results acquired from copy number analysis. Results show that the expression of identified reference genes varied in comparing groups composed of different type of life stages. It is suggested that 18S rDNA and TubB could be used for highly complex samples composed of mixed ploidy and phases. 18S rDNA and 28S rDNA were also preferred for using among the matured isomorphic samples. But for samples with different maturities, TubB and ACT were recommended for tetrasporophytes and gametophytes respectively. [ABSTRACT FROM AUTHOR]

To date, organic–inorganic hybrid perovskite solar cells (PSCs) have reached a certified efficiency of 25.7%, showing great potential in upscale industrial commercialization. However, a huge obstacle facing the industrialization of PSCs is the decreased efficiency and long‐term stability when upscaling the device area. To overcome these issues, blade‐coating methods have been developed to fabricate large‐area PSCs due to their capability to deposit uniform large‐area perovskite films. Ink engineering plays an important role in the blade‐coating, especially for crystallinity and defect control. In this review, the blade‐coating method to fabricate large‐area perovskite films is first introduced. Then, the perovskite ink engineering for blade‐coating PSCs is systematically summarized. Specifically, the effects of perovskite composition management and solvent engineering on perovskite film quality are discussed, and recent efforts in additive strategy to passivate perovskite defects are also summarized. Subsequently, recent advances in functional layer ink engineering and fully blade‐coated PSCs are summarized. Moreover, the applications of blade‐coating method in hole transporting material‐free carbon‐based PSCs are discussed. Finally, some suggestions and an outlook on this field are provided to help facilitate highly efficient and stable blade‐coated PSCs. [ABSTRACT FROM AUTHOR]

The hydrogen-fueled Wanke rotary engine is a promising power system that has both high power and eco-friendly properties. This work investigated the effect of ignition timing on a dual-spark plugs synchronous-ignition hydrogen-fueled Wankel rotary engine under low speed, part load and lean combustion. The results show that with delaying the ignition timing, CA0-10 is shortened first and then lengthened and CA10-90 is consistently shortened. When the CA50 is located between 35 and 40°CA ATDC, the maximum brake torque can be realized. Besides, the selection of ignition timing needs to consider the "trade-off" relationship between the combustion phase and corresponding in-cylinder pressure. The maximum brake torque ignition timing is between 5 and 10°CA ATDC. And there is also a "trade-off" relationship between stability and thermal load when ignition timing is selected. In addition, HC and NO emissions will not become the problem limiting the power performance of hydrogen-fueled Wankel rotary engine under this operating condition. • A modified synchronous ignition hydrogen Wankel rotary engine was used. • The effect of ignition timing on performance of rotary engine was studied. • The power depends mainly on the in-cylinder pressure near 135°CA ATDC. • Selecting ignition timing needs to weigh the stability and thermal load. • Suitable ignition timing makes CA50 located between 35 and 40°CA ATDC. [ABSTRACT FROM AUTHOR]

As essential transfer carriers for cell-to-cell communication and genetic material, exosomes carry microRNAs that participate in the regulation of various biological processes. MicroRNAs are a type of single-stranded noncoding RNA that bind to specific target gene mRNAs to degrade or inhibit their translation, thereby regulating target gene expression. Although it is known that a variety of microRNAs are involved in the viral infection process, there are few reports on specific microRNAs involved in porcine epidemic diarrhea virus (PEDV) infection. In this study, we isolated and identified exosomes in PEDV-infected Vero E6 cells. Using transcriptomics technology, we found that miRNA-328-3p was significantly downregulated in exosomes following PEDV infection. Moreover, exosomal miRNA-328-3p inhibited infection by PEDV by targeting and inhibiting tight junction protein 3 (TJP-3/ZO-3) in recipient cells. Our findings provide evidence that, after infecting cells, PEDV downregulates expression of miRNA-328-3p, and the resulting reduced inhibition of the target protein ZO-3 helps to enhance PEDV infection. These results provide new insight for understanding the regulatory mechanism of PEDV infection. [ABSTRACT FROM AUTHOR]

Purpose: College students' well-being is important for their self-growth and the whole society. However, we still know relatively little about how college students could proactively, strategically improve their well-being in the leisure context. Following the self-determination theory and proactivity literature, this study examines how and when leisure crafting (ie, a proactive act whereby individuals balance their leisure resources and demands by utilizing their personal abilities and needs) can enhance college students' well-being. Methods: Conducting a quantitative weekly diary study of 80 Chinese students in an engineering college (320 observations), we drew a moderated mediation model. Results: We found that weekly leisure crafting behaviors (ie, seeking structural leisure resources, seeking social leisure resources, seeking leisure challenges, and reducing hindering leisure demands) were positively related to weekly intrinsic need satisfaction (ie, need for competence, autonomy, and relatedness), then resulting in higher weekly subjective well-being (ie, physical thriving, mental health, and life meaningfulness). Moreover, this indirect effect was stronger for those who had a higher level of leisure boredom. Conclusion: Our study contributes to student development and well-being literature by focusing on the students' leisure context and providing a means to enhance their well-being. We unfold how the leisure crafting strategy boosts college students' well-being via increasing their intrinsic need satisfaction. We also highlight the compensating role of leisure crafting when one is in an unfavorable personal state (eg, leisure boredom). [ABSTRACT FROM AUTHOR]

The surface urban heat island intensity (SUHII) when using nadir‐viewing radiometric and complete surface temperature (Tr and Tc) was evaluated. The urban areas of the Kowloon peninsula and Hong Kong Island were selected and four daytime Landsat TM images and two nighttime ASTER images were collected to retrieve Tr and then model Tc based on a semi‐empirical model. SUHIIs were estimated using both the retrieved Tr and modelled Tc. High spatial resolution (HR) airborne thermal images (0.2 m) observed at 12:10 noon on Oct 24, 2017 were used to retrieve Tc directly. Results based on HR data and satellite data were consistent and indicated that the geometry of the built‐up space had a larger impact on SUHII when using Tc (SUHIIc) than Tr (SUHIIr). During daytime SUHIIc decreased while SUHIIr showed a very slight increase with building density. Both SUHIIc and SUHIIr decreased with higher building height but the rate of decrease of SUHIIc was higher than SUHIIr. Both SUHIIc and SUHIIr decreased with increasing building height variance and increased with increasing sky view factor (SVF). The rate of decrease with building height variance for SUHIIc was larger than SUHIIr. The rate of increase of SUHIIc with SVF was higher than SUHIIr. During nighttime, geometry effects on SUHIIc and SUHIIr were different from daytime. Both SUHIIc and SUHIIr increased with building density, while the rate of increase of SUHIIc with building density, as well as with building height, was much higher than SUHIIr. Both SUHIIc and SUHIIr decreased with SVF, but the rate of decrease of SUHIIc was higher than SUHIIr. Both SUHIIc and SUHIIr initially increased with building height variance and then remained approximately constant. We also evaluated the UHI intensity: SUHIIc was much closer to UHII than SUHIIr. Overall, building geometry had larger impact on SUHIIc than on SUHIIr, that is, SUHIIc is more representative of urban climate than SUHIIr. [ABSTRACT FROM AUTHOR]

Background: The development of tumor cells inside the lymphatics or blood vessels is known as lymphovascular invasion (LVI). The correlation between LVI, lymph node metastasis (LNM), and the diagnosis of superficial esophageal carcinoma (SEC) remains unclear.Methods: We searched Embase, PubMed, Web of Science, and Cochrane Library databases for prospective articles to better understand the relationship between LVI, LNM, and SEC diagnosis.Results: We included 23 articles containing data for 4749 patients (range: 54-598) in our meta-analysis. The hazard ratio between LVI and overall survival (OS) was 1.85 with 95% confidence interval (CI) (1.10-3.11, P = 0.02). LNM rate was higher in SEC patients with LVI than SEC patients without LVI (univariate: OR = 4.94, 95% CI: 3.74-6.53, P < 0.0001; multivariate: OR = 5.72, 95%CI: 4.38-7.4, P < 0.0001). No obvious publication was found.Conclusions: The results indicate that LVI plays a dominant role in the prognosis of LNM in SEC and in the prognostic prediction for SEC. [ABSTRACT FROM AUTHOR]

Highlights • A CFD model of H 2 -gasoline fueled rotary engine was established and validated. • The CFD model was modified by installing the compound intake ports. • The mean in-cylinder pressure and indicated thermal efficiency were increased. • Combining compound intake with HDI obtained a better engine performance. • CO emission was decreased, but NOx emissions were increased. Abstract The compound intake possesses large port area. Applying it in Wankel rotary engine (WRE) could increase volumetric efficiency and reduce pumping loss. To investigate the effect of the compound intake on the mixture formation and combustion process in gasoline WREs with hydrogen port and direct injected (HPI and HDI) enrichment, a three-dimensional computational fluid dynamics (CFD) model was established and validated. Investigation results showed that the peripheral-ported intake flow plays a leading role in the compound-ported WRE. Because the peripheral-ported intake flow has the same direction with the rotor movement, the formation time of mainstream flow field is shortened and the mean flow speed is increased, the flame propagation in the same direction with mainstream flow field is accelerated. Meanwhile, the improvements in volumetric efficiency and quality of in-charged mixtures result in the rise of temperature and pressure at spark timing, which could also improve the initial thermal conditions. Therefore, the compound intake effectively accelerates the combustion process in WRE. In HPI conditions, compared with the side-ported WRE, the peak in-cylinder pressure and indicated thermal efficiency in compound-ported WRE are respectively increased by 4.5% and 3.9%. In HDI conditions, the flame could propagate to the rear combustion chamber and eliminate the unburned zone, the maximum in-cylinder pressure and indicated thermal efficiency in side-ported WRE with HDI are 84.7% and 6.6% higher than those of in side-ported WRE with HPI. At the same time, the compound intake could further increase the in-cylinder pressure and indicated thermal efficiency by 6.8% and 2.5%, respectively. However, the improved combustion performance increases the in-cylinder temperature, which provides a suitable thermal-atmosphere for nitrogen oxide (NO x) formation. The compound intake increases mass fractions of NO x emissions from 0.111% to 0.141% in HPI conditions and those from 0.268% to 0.284% in HDI conditions. Considering the compound intake promotes the combustion characteristics and effectively decreases carbon monoxide (CO) emission from 0.043% to 0.033% in HPI conditions, and from 0.008% to 0.003% in HDI conditions, it is a feasible way to improve the performance of WREs. Especially, combining it with HDI could obtain a better engine performance under low engine speed and part load conditions. [ABSTRACT FROM AUTHOR]

Aim: To investigate the incidence, risk factors, and the last follow-up recovery status of sciatic and femoral nerve injury among patients who received Bernese peri-acetabular osteotomy (PAO).Patients and Methods: The clinical file of 643 consecutive patients who received PAO from June 2012 to June 2016 was retrospectively reviewed. The number of nerve injury patients was calculated and the causes of injury were recorded.Results: The sciatic or femoral nerve injury occurred in eight patients (1.24%), including four sciatic nerve injuries and four femoral nerve injuries. The reasons for sciatic nerve injury included one direct sciatic nerve injury happened at the time when deep osteotomy penetrated the posterior column to cut the nerve trunk at the area where the nerve runs through out of the greater sciatic foramen during quadrilateral bone osteotomy. The other two direct sciatic nerve injuries occurred at the inside pelvis by long drill bit or Kirschner wire drilling before the transverse screw fixation. No direct injury reasons could be found for the remaining five patients with one partial sciatic nerve injury and four femoral nerve palsies. The three patients with direct sciatic nerve injuries were partly recovered at the last follow-up. Full recovery was found in one sciatic nerve injury and four femoral nerve injury patients.Conclusion: The sciatic nerve can be injured directly or indirectly during PAO. It is of great importance to understand the risk factors and the precautionary measures of nerve injuries during PAO. [ABSTRACT FROM AUTHOR]

Abstract The comparative study on performance of the hydrogen/gasoline and hydrogen/n-butanol rotary engines was conducted in the present paper. Considering the stable operation of the engine, for both hydrogen/gasoline case and hydrogen/n-butanol case, the operating conditions were set at: 4000 rpm (engine speed), 35 kPa (intake pressure) and 30 °CA BTDC (spark timing). The total excess air ratio of mixture was maintained at 1.0 through all the tests. The testing results displayed that hydrogen enrichment improved performance of both gasoline and n-butanol rotary engines. To be more specific, brake thermal efficiency was increased, flame development and propagation periods were shortened, the coefficient of variation in flame propagation period was decreased, and the emissions of HC and CO were decreased. NOx emissions were mildly increased after hydrogen addition. Besides, hydrogen/n-butanol rotary engine possessed the similar performance to hydrogen/gasoline rotary engine. Highlights • Performance of HGRE and HBRE was studied. • BTE and Tmax was increased after H 2 blending. • CA0-10, CA10-90 and engine instability were shortened by H 2 addition. • H 2 addition resulted in the reduced HC and CO emissions. • HBRE shares highly similar performance with HGRE. [ABSTRACT FROM AUTHOR]

Hesitant fuzzy set theory provides an effective technique for researchers and engineers to cope with vagueness and uncertainty. In recent years, to explore the correlation between hesitant fuzzy sets, traditional correlation measure in statistics has been constantly studied in hesitant fuzzy environments. In this study, extant studies of correlation measures in hesitant fuzzy contexts are recalled and analyzed. In view of the forgoing analysis, we find out that the extant correlation coefficients have some limitations. Moreover, a few correlation coefficients are not in line with the traditional definition of correlation coefficients. In order to address the flaws of the existing proposals, a novel hesitant fuzzy correlation coefficient is proposed in this study. The new proposal of this study can not only overcome the flaws of the old hesitant fuzzy correlation coefficients, but it also shows several desirable characteristics. The weighted form of the newly defined correlation coefficient and its features are also investigated. Finally, three numerical examples concerning supplier selection and medical diagnosis are examined using the developed correlation coefficients to demonstrate their applicability. Comparison analyses with existing proposals highlight the efficiency of our proposals. [ABSTRACT FROM AUTHOR]

Highlights • A CFD model of H 2 -gasoline fueled rotary engine was established and validated. • H 2 was direct injected in the combustion chamber under different strategies. • In-cylinder pressure increased with retarded HIT and extended HID. • The lowest CO emission was achieved in HIT of 110 °CA BTDC, HID of 40 °CA. • Higher NO x emissions were acquired in retarded HIT and extended HID. Abstract In Wankel rotary engine (WRE), high mainstream velocity in combustion chamber blocks flame propagating to the end of combustion chamber, which causes high emissions and low combustion efficiency due to unburned mixtures. To solve this problem, a three-dimensional dynamic simulation model of a hydrogen-gasoline blends fueled WRE is built and validated. The in-cylinder mixture formation and combustion process are investigated under different hydrogen injection timing (HIT) and duration (HID) conditions. The study results show that the concentration of hydrogen distributed between the spark plug region and rear combustion chamber increases with retarded HIT and extended HID. Faster flame speeds are obtained for HIT of 110 °CA BTDC and HID of 40 °CA. At a fixed HID of 20 °CA, compared with HITs of 210 and 160 °CA BTDC, the peak in-cylinder pressures for HIT of 110 °CA BTDC are increased by 14.3% and 6.8%, respectively. At a fixed HIT of 110 °CA BTDC, the peak in-cylinder pressure in HID of 40 °CA is 52.3% and 9.21% higher than HIDs of 20 and 30 °CA. The highest in-cylinder pressure is achieved with the hydrogen injection strategy that HIT of 110 °CA BTDC, HID of 40 °CA. However, as the temperature increases with pressure, nitrogen oxide emissions are also increased with retarded HIT and extended HID obviously. Considering the lowest carbon monoxide is achieved and the unburned zone in the rear region of combustion chamber is eliminated in HIT of 110 °CA BTDC, HID of 40 °CA. The hydrogen direct injection strategy that HIT of 110 °CA BTDC, HID of 40 °CA acquires the best engine performance in this research. [ABSTRACT FROM AUTHOR]

This paper aims to reveal the effect of intake closing timing, and engine speed on the flow field, flame propagation, combustion characteristics, and emissions formations of a small-scaled side ported hydrogen-fueled Wankel rotary engine. For this reason, a three-dimensional dynamic simulation model was established using a reasonable turbulent model coupled with a kinetic reaction mechanism and validated by the experimental data. Simulation results show that an earlier intake closing timing increases the volumetric efficiency and increases intake loss. The increasing speed improves the volumetric efficiency while causing a higher intake loss. There are two peaks of the turbulence kinetic energy during the intake stroke. The first one is caused by the airflow hitting the wall, and the other is due to the backflow. During the flame development period, due to the strong unidirectional flow in the combustion chamber, which is not conducive to flame propagation backward. This phenomenon is more pronounced at higher engine speeds, resulting in a merged flame front not exceeding the trailing spark plug. The lean combustion leads to a lower in-cylinder combustion temperature, deteriorating the NOx generation environment. This paper provides a feasible method for matching the operating conditions and intake system. • The shape and area of the intake port varies with the intake closing timing. • Dual-spark plug flame propagation pattern is proposed. • The leakage of gas to adjacent cylinder is reduced at 8000 rpm. [ABSTRACT FROM AUTHOR]

Under the background of carbon neutral, hydrogen-fueled Wankel rotary engine (WRE) with high power density and compact layout has the potential to become a substitute for current fossil engines. Ammonia as a carbon-free renewable energy is considered alternative energy used in vehicles, however, its application on WRE is lacking. Therefore, the present work aims to investigate the performance of ammonia-enriched hydrogen-fueled WRE to analyze the feasibility of ammonia applied in hydrogen-fueled WRE. The main conclusions are as follows: Under test conditions, the maximum brake torque and thermal efficiency are obtained at about 30% and 40% volume fraction of ammonia in fuel, and compared with pure hydrogen conditions, achieving relative improvements of 21% and 29%, respectively. Slightly rich combustion is recommended to increase power and decrease NO emissions with an acceptable economic loss. In addition, ammonia enrichment can prevent the occurrence of abnormal combustion. [Display omitted] • Performance analysis of NH3-enriched hydrogen-fueled Wankel rotary engine. • NH3 enrichment can improve dynamics and economy with penalties for NO emission. • Slightly rich combustion is recommended for NH3-enriched hydrogen-fueled WRE. • NH3 enrichment is an effective way to prevent abnormal combustion. [ABSTRACT FROM AUTHOR]

A CFD model of hydrogen-enriched gasoline Wankel rotary engine is established and validated. The mixture formation and combustion processes are investigated under both hydrogen port and direct injection enrichment conditions with different hydrogen addition levels. It was found that, under hydrogen port injection enrichment conditions, the peak in-cylinder pressure of 6% is 8.4% higher that of 3%. Meanwhile, under hydrogen direct injection enrichment conditions, the peak in-cylinder pressure of 3% hydrogen direct injection enrichment is 15.3% higher than that of 3% hydrogen port injection enrichment. It was also found that the mainstream field with same direction of rotor rotation is formed during the compression stroke and a vortex with high vorticity existed in the combustion chamber. With the effects of mainstream field and vortex, the hydrogen fills more than half volume of the entire combustion chamber under 4%, 5% and 6% HDIE conditions. At the same time, a local low velocity zone is formed around the vortex because the hydrogen direct injection flow slows down the dissipation of vortex. According to the analysis by PREMIX, the fastest flame speed is achieved at equivalence ratios around 1.4. The proper rich hydrogen region distribution is obtained under 4%, 5% and 6% hydrogen direct injection enrichment conditions. Both the enhanced flame propagation by proper equivalence ratio distribution and the reduced local mainstream flow velocity by vortex existence contribute to solving the unburned zone problem. Compared with 6% hydrogen port injection enrichment, the maximum value of in-cylinder pressure of 4%, 5% and 6% hydrogen direct injection enrichment is improved by 59.6%, 88.4% and 91.6%, respectively. However, carbon monoxide and nitrogen oxide emissions are increased obviously. As a relatively low carbon monoxide emission is obtained with 4% case under hydrogen direct injection enrichment conditions and the problem of unburned zone in the rear region of combustion chamber is solved. The hydrogen volume fraction of 4% with direct injection enrichment achieves the best engine performance in this study. [ABSTRACT FROM AUTHOR]

Magnetic resonance imaging (MRI) is a very powerful technique increasingly used in food engineering, yet examples where the local water content is quantified are scarce. Homogeneous whey protein hydrogels were utilized as a model system, far simpler than most foods. The normalized proton density intensity of hydrogels was predicted using experimental correlations of the spin-lattice and spin-spin relaxation times, T 1 and T 2 respectively. Using a typical echo time T E of 20 ms, the intensity is maximum at a volumetric swelling ratio Q ∼15, and MRI is suitable to study the drying of hydrogels at lower Q values. Swelling can be studied by adjusting T E to target the Q range of interest, e.g. ∼200 ms. Whereas reasonable agreement is found between predicted normalized intensities and from drying and swelling experiments, local quantification of Q in unknown conditions will suffer from noise and relatively poor repeatability. Deviations from predictions are observed in the swelling at high NaCl concentrations, and at high alkaline pH, that need to be studied further. Opaque particulate hydrogels can be studied equally well compared to stranded transparent gel, a clear advantage against optical techniques. [ABSTRACT FROM AUTHOR]

The study aims to numerically investigate the combustion and emissions formation processes in a spark-ignition rotary engine fueled with hydrogen-gasoline blends. The Renormalization Group k-ε turbulence coupled with a skeletal primary reference fuel mechanism were adopted to simulate the engine working process under 0%, 2% and 4% hydrogen volume fractions in CONVERGE software. The flow field variation and detailed combustion processes were analyzed and discussed. Results showed that a mainstream flow field along with the rotor movement was formed during the compression stroke and sustained in the combustion chamber until the exhaust valve opening. The center of the burned zone would move in same direction with the mainstream flow. Meanwhile, due to the effect of the mainstream flow, the flame propagation in direction of the mainstream flow was expedited. While the flame propagation in contrary direction was retarded, consequently, the unburned mixtures at rear region of combustion chamber suffered incomplete combustion. The distributions of nitric oxide and carbon monoxide emissions were also dominantly affected by the flow field in the combustion chamber. After hydrogen addition, the increased OH, H and O radicals concentrations combined with the intense flow flied accelerated the combustion process, which resulted in the improvement and advancement of in-cylinder pressure and temperature. Compared with original gasoline case, the peak in-cylinder pressure was increased by 9.1% and 13.7% with 2% and 4% hydrogen blends, respectively. With hydrogen enrichment, the increased in-cylinder temperature promoted the formation of nitric oxide emission. Besides, Carbon monoxide emission was decreased with the increase of hydrogen addition fraction. [ABSTRACT FROM AUTHOR]

Twelve ro-vibrational energy levels of the 85 Rb 2 b 3 Π 1 u state have been observed using the Perturbation Facilitated Infrared-Infrared Double Resonance (PFIIDR) technique for the first time.Using the new observed levels as intermediate window levels, dozens of transitions into the 85 Rb 2 2 3 Π 1 g upper state ro-vibrational levels have been recorded.Compared with the experimental data of the 85 Rb 2 2 3 Π 0 g state, the average term value difference between the observed Ω = 1 and Ω = 0 components of the 85 Rb 2 2 3 Π g state levels with the same rotational quantum number, is approximately 83.1 ± 0.3 cm - 1 . This proves that the 2 3 Π g state has a spin-orbit splitting of 83.1 ± 0.3 cm - 1 , which shows that the 2 3 Π g state tends to belong to Hund’s case (a). [ABSTRACT FROM AUTHOR]

This study aims to evaluate the effects of urban geometry on retrieval of emissivity and surface temperature in urban areas. An improved urban emissivity model based on sky view factor (IUEM-SVF) was further enhanced to consider all radiance contributions leaving the urban canopy, including (i) emission by all facets within an instantaneous field of view (IFOV); (ii) reflection by all facets of emission from surrounding facets; and (iii) propagation of emitted and reflected radiation with multiple reflections (scattering) within a complex 3D array of urban objects. The effective emissivity derived from IUEM-SVF was evaluated with a microscale radiative transfer and energy balance model: Temperatures of Urban Facets in 3-D (TUF-3D). IUEM-SVF performs well when urban facets have uniform emissivity and temperature; e.g., root mean square deviations (RMSD) are less than 0.005 when material emissivity is larger than 0.80 (ɛ ⩾ 0.80). However, when material emissivities are variable within the observed target, differences of effective emissivity between IUEM-SVF and TUF-3D become larger, e.g., RMSD of 0.010. When the effect of geometry is not considered and a mixed pixel emissivity is defined, the difference is even much larger (i.e. 0.02) and this difference increases with the decrease of sky view factor. Thus, the geometry effect should be considered in the determination of effective emissivity. Effective emissivity derived from IUEM-SVF was used to retrieve urban surface temperature from a nighttime ASTER thermal infrared image. Promising results were achieved in comparison with standard LST products retrieved with the Temperature and Emissivity Separation (TES) algorithm. IUEM-SVF shows promise as a means to improve the accuracy of urban surface temperature retrieval. The effect of thermal heterogeneity on the effective emissivity was also evaluated by TUF-3D, and results show that the thermal heterogeneity cannot be neglected since the RMSD between the effective emissivity based on TUF-3D and IUEM-SVF is relatively large. [ABSTRACT FROM AUTHOR]

Idle elimination is a feasible way for reducing the fuel consumption and emissions at idle. The challenge for adopting idle elimination on gasoline engine is the high emissions during restart because rich mixtures have to be used at starting. This paper tries to start the engine with pure hydrogen at the restart for gasoline vehicles which adopt idle elimination. The investigation was done based on models built on AVL CRUISE. In the model, the vehicle was run under the New European Driving Cycle (NEDC). The hydrogen used on the vehicle was online produced and stored by an on-board hydrogen production and storage system. The energy for producing hydrogen is taken into account in the total fuel consumption. The simulation results showed that, with the adoption of gasoline start-idle elimination strategy, the vehicle fuel consumption during NEDC was reduced by 0.69 L/100 km, and NO x emissions were decreased by 5.5% compared with the original vehicle without idle elimination. However, HC and CO emissions at the restart were respectively increased by 87.5% and 18.1% for the gasoline vehicle due to the adoption of rich mixtures. Comparatively, with the adoption of hydrogen start-idle elimination strategy, the vehicle fuel consumption during NEDC was reduced by 0.79 L/100 km, HC and CO emissions were decreased by 70.8% and 13.6%, respectively. This shows a good capability of hydrogen combustion on reducing HC and CO emissions at the restart. However, NOx emissions were slightly increased by 7.9% under the hydrogen restart mode. [ABSTRACT FROM AUTHOR]

A two-zone quasi-dimensional model is developed and validated for predicting the performance of a hydrogen-enriched methanol engine. The fractal-based turbulent entrainment model was applied to hydrogen-enriched methanol combustion simulations with a laminar flame speed correlation of hydrogen-methanol-air mixtures. The model accuracy was evaluated under different hydrogen volume fractions, equivalence ratios, loads and speeds. Satisfying agreement between numerical and experimental results was achieved. The validated model was applied to investigate the flame propagation speed, exhaust loss and brake thermal efficiency of hydrogen-enriched methanol engines. The results showed that the hydrogen enrichment could improve the flame propagation speed, reduce the exhaust loss and enhance brake thermal efficiency. Moreover, the results suggested that, for the actual vehicular engine operation, the hydrogen addition should be coupled with the lean burn strategy under low speed and part load conditions. [ABSTRACT FROM AUTHOR]

This study presents a Single Channel Method using Urban Exitance Model (UEM-SCM) to retrieve land surface temperature (LST) from satellite data in an urbanized city, and evaluates the geometry effect on land surface temperature retrieval using single channel method and split-window algorithm. The UEM-SCM incorporates the effect of urban geometry and considers both reflection caused by the target pixel and its neighboring pixels. In order to evaluate the geometry effect, the retrieved LSTs with and without geometry effect were studied. Results show that the LSTs without geometry effect are generally higher than the LSTs with geometry effect. The temperature difference occurs because the material emissivity is always lower than the effective emissivity caused by multiple scattering and reflection in urban areas (cavity effect). The LST without geometry effect also cannot fully capture the variability and complexity of urban thermal patterns. The temperature difference between with and without the geometry effect can reach 2 K in built-up areas. A comparison was also conducted between LST retrieved by split-window algorithm with and without geometry effect. Results show that the LST retrieved by split-window algorithm without geometry effect has generally higher values than the one with the geometry effect, e.g. 1.1 K on average and 1.5–2 K in built-up areas. The geometry effect will be removed and mis-deemed as atmospheric effect when the split-window algorithm without geometry effect is applied in urban areas. The split-window algorithm with the geometry effect can be used to distinguish between geometry and atmospheric effect in further study. [ABSTRACT FROM AUTHOR]

The hydrogen-fueled Wankel rotary engine with excellent power and emission characteristic is under spotlight, while the leakage is still the major problem for Wankel rotary engine, especially the leading spark plug leakage. The peak pressure is increased from 3.34 MPa to 3.52 MPa and the indicated thermal efficiency reaches maximum value of 38.29% when the moving distance of leading spark plug is −6.5 mm, and the mass of leakage fresh mixture is reduced from 0.00311 g to 0 g. When leading spark plug is moved to minor axis, the flow field structure of working chamber is enhanced. However, the peak pressure and indicated thermal efficiency decrease when the moving distance of leading spark plug exceeds −6.5 mm. The excess leakage residual gas has negative effects on combustion. The optimum moving distance of leading spark plug is −6.5 mm at 3000 rpm with λ of 1.6. • The leakage mechanisms of spark plugs are analyzed. • The influence of leading spark plug location on gas leakage is analyzed. • The influence of leading spark plug location on combustion is analyzed. • The influence of leading spark plug location on flow field is analyzed. • The optimum location of leading spark plug is given. [ABSTRACT FROM AUTHOR]

Ink Engineering in Blade-Coating Large-Area Perovskite Solar Cells (Adv. Keywords: blade coating; ink engineering; large area; perovskite solar cells EN blade coating ink engineering large area perovskite solar cells 1 1 1 07/29/22 20220727 NES 220727 B Perovskite Solar Cells b Upscaling perovskite solar cells is a key factor for their industrialization. In article number 2200975, Zhanhua Wei and co-workers discuss the ink engineering in blade-coating large-area perovskite solar cells. [Extracted from the article]

Surface emissivity is a critical parameter for studying city-, meso-, and micro-scale climate and energy balance. The emissivity of complex surfaces e.g. a forest or an urban canopy is an effective surface property since it depends on both surface materials and geometry. This study presents a novel methodology for estimating effective emissivity using sky view factor retrieved from airborne Lidar data, building GIS data, and land use and land cover classification data. First, a high correlation between the effective emissivity retrieved from ASTER TIR bands 10–14 and the sky view factor was observed ( r 2 = 0.93, 0.99, 0.99, 0.97, 0.97). When the sky view factor decreases, the effective emissivity tends to increase, which is mainly due to multiple scattering (cavity effect), thus increases the effective emissivity. A simplified model which assumes that reflection and scattering only occurs within a single pixel was developed. Results showed that the correlations between the modeled and the spectral (band) emissivity retrieved from the ASTER multispectral TIR data (five spectral bands) are high ( r 2 = 0.93, 0.99, 0.98, 0.93, 0.97), and with low RMSE (0.019, 0.016, 0.012, 0.003 and 0.004 from band 10–14 respectively). The emissivity derived from this simplified model, however, tends to be overestimated in band 10–12. Thus, a refined urban emissivity model based on sky view factor (UEM-SVF) which considers the scattering and reflection from adjacent pixels was developed in this study. Results show a good agreement with ASTER spectral (band) emissivity: r 2 = 0.90, 0.98, 0.96, 0.94 and 0.96, and very low RMSE (0.006, 0.003, 0.004, 0.002 and 0.004). This study illustrates that the UEM-SVF can be useful for estimation of land surface emissivity of complex surfaces, and can further be used for accurate land surface temperature retrieval. [ABSTRACT FROM AUTHOR]

Hydrogen-fueled internal combustion engine is proposed to resist the threat of global warming. Wankel rotary engine (WRE) has been proven to be an excellent hydrogen-fueled power device, which can overcome the shortcomings of hydrogen, such as poor power, serious backfire and large storage volume, to some extent when it is used as fuel in the internal combustion engine. However, due to its unique structure, WRE suffers from severe knock. Therefore, the goal of this work is to investigate the impacts of knock type on the heat release process in hydrogen-fueled WRE. This present work is conducted at 2000 r/min and wide-open throttle. The main results are as follows: In hydrogen-fueled WRE, the peak knock pressure of knock caused by rapid and unstable combustion of hydrogen is usually earlier than CA50 and that of knock caused by spontaneous combustion of end gas is usually later than CA50. The sequence between the crank angle of peak knock pressure and CA50 combined with knock intensity can be used to determine the knock type in hydrogen-fueled WRE. Besides, a means for knock detection is proposed according to the distribution of crank angle corresponding to peak knock pressure. In addition, the distribution of CA0-10, CA50 and CA10-90 of 1000 consecutive cycles under two kinds of knock in hydrogen-fueled WRE are discussed in detail, and regular conclusions are drawn. In particular, the limitation of CA50 as a metric for evaluating knock level is also demonstrated. • The impact of knock type on the heat release of hydrogen Wankel engine is discussed. • The distribution of CA0-10, CA50 and CA10-90 with knock intensity are analyzed. • A method is proposed to estimate the knock occur. • A method is proposed to determine the knock type in hydrogen engines. [ABSTRACT FROM AUTHOR]

• Effect of Spark plug position on hydrogen rotary engine is investigated. • Leading spark plug can obtain higher power and low cyclic variation. • Hydrogen rotary engine's spark plug should locate the front of the minor axis. • Hydrogen rotary engine has excellent emission under lean combustion. • Best CA50 of hydrogen rotary engine locates between 35 and 40°CA ATDC. As a promising power system, hydrogen-fueled Wankel rotary engine with excellent power and emission characteristic have received attention increasingly, which makes it of great interest to investigate it. To make up for blanks, this work was conducted to experimentally investigate the effect of spark plug position on the combustion and emission characteristic of hydrogen-fueled Wankel rotary engine under 1500 r/min, 66 kPa manifold absolute pressure and 1.5 excess air ratio. The results indicate that compared to the trailing spark plug, the leading spark plug is more suitable to hydrogen-fueled Wankel rotary engines, which can realize a wider ignition range, higher maximum brake torque, lower cyclic variation and better nitric oxide emission. The maximum brake torque of adopting trailing spark plug is 31.2 N·m, which is only 87% of the maximum brake torque of 36.0 N·m with adopting leading spark plug. At the maximum brake torque ignition timing, adopting leading trailing spark plug achieves lower cyclic variation and slightly higher thermal load than adopting trailing spark plug. Besides, the optimum central heat-release point of both spark plug positions locate between 35 and 40°CA after the top dead center, and that of leading spark plug is later 2°CA than that of trailing spark plug. Moreover, both spark plug positions obtained 0 nitric oxide emission at maximum brake torque ignition timing, which means that emission will not be a problem to limit the selection of spark plug position under tested conditions. [ABSTRACT FROM AUTHOR]

Abstract: A superhydrophobic surface was obtained by combining application of CaCO3/SiO2 mulberry-like composite particles, which originated from violent stirring and surface modification, and self-assembly of polydimethylsiloxane. Water contact angle and sliding angle of the superhydrophobic surface were measured to be about 164±2.5° and 5°, respectively. The excellent hydrophobicity is attributed to the synergistic effect of micro–submicro–nano-meter scale roughness (fabricated by composite particles) and the low surface energy (provided by polydimethylsiloxane). This procedure makes it possible for widespread applications of superhydrophobic film due to its simplicity and practicability. [Copyright &y& Elsevier]

Harmonization of satellite imagery provides a good opportunity for studying land surface temperature (LST) as well as the urban heat island effect. However, it is challenging to use the harmonized data for the study of LST due to the systematic bias between the LSTs from different satellites, which is highly influenced by sensor differences and the compatibility of LST retrieval algorithms. To fill this research gap, this study proposes the comparison of different LST images retrieved from various satellites that focus on Hong Kong, China, by applying diverse retrieval algorithms. LST images generated from Landsat-8 using the mono-window algorithm (MWAL8) and split-window algorithm (SWAL8) would be compared with the LST estimations from Sentinel-3 SLSTR and Himawari-8 using the split-window algorithm (SWAS3 and SWAH8). Intercomparison will also be performed through segregated groups of different land use classes both during the daytime and nighttime. Results indicate that there is a significant difference among the quantitative distribution of the LST data generated from these three satellites, with average bias of up to −1.80 K when SWAH8 was compared with MWAL8, despite having similar spatial patterns of the LST images. The findings also suggest that retrieval algorithms and the dominant land use class in the study area would affect the accuracy of image-fusion techniques. The results from the day and nighttime comparisons revealed that there is a significant difference between day and nighttime LSTs, with nighttime LSTs from different satellite sensors more consistent than the daytime LSTs. This emphasizes the need to incorporate as much night-time LST data as available when predicting or optimizing fine-scale LSTs in the nighttime, so as to minimize the bias. The framework designed by this study will serve as a guideline towards efficient spatial optimization and harmonized use of LSTs when utilizing different satellite images associated with an array of land covers and at different times of the day. [ABSTRACT FROM AUTHOR]

The development of hydrogen-fueled Wankel rotary engine is restricted by the leakage problem, especially the apex seal leakage (ASL). In the study, the ASL area is divided into the geometric leakage area (GLA) and the dynamic leakage area (DLA). The models of under-seal pressure prediction and vibration of apex seal are established. The mechanism of GLA and DLA and the effects of key parameters on them are analyzed. Results show that the DLA decreases with the increase of discharge coefficient, clearance between apex seal and slot. There is no DLA when the rotation speed is slower than 2000 rpm or higher than 7000 rpm. Besides, the value of DLA is only 11.23% of GLA and the GLA can be reduced by 88.57% when using a corner-piece structure. The total leakage decreases with the increase of rotation speed. Finally, some measures to reduce the leakage are given. [Display omitted] • The cause of apex seal leakage of the Hydrogen Wankel rotary engine is analyzed. • The prediction model of under-seal pressure of the apex seal is established. • The computational model of the apex seal leakage is established. • The apex seal leakage area and leakage gas mass are calculated. • The suggestions to improve the sealing performance are given. [ABSTRACT FROM AUTHOR]

Satellite-derived rugged land surface temperature (LST) is an important parameter indicating the status of the Earth's surface energy budget and its seasonal/temporal dynamic change. However, existing LST products from rugged areas are more prone to error when supporting applications in mountainous areas and Earth surface processes that occur at high spatial and temporal resolutions. This research aimed to develop a method for generating rugged LST with a high temporal and spatial resolution by using an improved ensemble LST model combining three regressors, including a random forest, a ridge, and a support vector machine. Different combinations of high-resolution input parameters were also considered in this study. The input datasets included Moderate Resolution Imaging Spectroradiometer (MODIS) LST datasets (MxD11A1) for nighttime, temporal Sentinel-2 Multispectral Instrument (MSI) datasets, and digital elevation model (DEM) datasets. The 30 m rugged LST datasets derived were compared against an in situ LST dataset obtained at Saihanba Forest Park (SFP) sites and an ASTER-derived 90 m LST, respectively. The results with in situ measurements demonstrated significant LST details, with an R2 higher than 0.95 and RMSE around 3.00 K for both Terra/MOD- and Aqua/MYD-based LST datasets, and with slightly better results being obtained from the Aqua/MYD-based LST than that from Terra/MOD. The inter-comparison results with ASTER LST showed that over 80% of the pixels of the difference image for the two datasets were within 2 K. In light of the complex topography and distinct atmospheric conditions, these comparison results are encouraging. The 30 m LST from the method proposed in this study also depicts the seasonality of rugged surfaces. [ABSTRACT FROM AUTHOR]

As a hydrogen carrier, ammonia can suppress knock and enhance thermal efficiency of the hydrogen-fueled Wankel rotary engine (WRE), and achieve zero carbon emissions. This research established a three-dimensional fluid dynamics model coupled with detailed reaction kinetics of ammonia and hydrogen and verified it based on experiments. Incorporating 10% volume fraction of ammonia into the hydrogen-fueled WRE eliminates knock and decreases the excess air ratio (λ) from 1.8 to 1.4, effectively improving the indicated mean effective pressure (IMEP). The results indicate that when λ exceeds 1.4, flame propagation accelerates with higher concentration of the mixture. This enhances peak in-cylinder pressure and heat release rate, but it results higher NOx emissions. As λ varies from 1.8 to 1.4, NOx emission levels rise by 47.4%. At λ ≤ 1.2, the rapid flame propagation leads to short combustion duration, diminishing the power output. At this stage, the NO formation is dominated by H radicals, and the NOx production reaches its minimum value at λ of 1.0. In summary, the ammonia-hydrogen WRE achieves optimal performance at λ of 1.4 and ignition timing of −5 °CA after top dead center, the indicated thermal efficiency reaches 36.9% and the IMEP achieves 0.683 MPa. • The effect of ammonia addition on hydrogen-fueled WRE is analyzed. • The addition of ammonia is an effective way to prevent abnormal combustion. • The effects of excess air ratio on combustion and emission are analyzed. • The optimum ignition timing corresponding the optimal performance is given. • The optimum IMEP and ITE is obtained when the excess air ratio equals 1.4. [ABSTRACT FROM AUTHOR]

The complete surface temperature (T c) in urban areas, defined as the mean temperature of the total active surface area, is an important variable in urban micro-climate research, specifically for assessment of the urban surface energy balance. Since most vertically-oriented building facets are not observed by a nadir-viewing remote imaging radiometer, the radiometric surface temperature (T r) measured at a specific view angle cannot be used with existing heat transfer equations to estimate radiative and convective fluxes in the urban environment. Thus, it is necessary to derive T c for city neighborhoods. This study develops a simple method to estimate T c from T r with the aid of the Temperatures of Urban Facets in 3D (TUF-3D) numerical model, which calculates 3-D sub-facet scale urban surface temperatures for a variety of surface geometries and properties, weather conditions and solar angles. The effects of geometric and meteorological characteristics – e.g., building planar area index (λ p), wall facet area index (F), solar irradiance – on the difference between T c and T r were evaluated using the TUF-3D model. Results showed the effects of geometric and meteorological characteristics on the difference between T c and T r differ between daytime and nighttime. The study then sought to predict the relationship between T r and T c , using λ p , F , and solar irradiance for daytime and only using λ p and F for nighttime. Based on the simulated data from TUF-3D, the resulting relationships achieve a coefficient of determination (r 2 ) of 0.97 and a RMSE of 1.5 K during daytime, with corresponding nighttime values of r 2 = 0.98 and RMSE = 0.69 K. The relationships between T r and T c are evaluated using high resolution airborne thermal images of daytime urban scenes: r 2 = 0.75 and RMSE = 1.09 K on August 6, 2013 at 12:40 pm; and r 2 = 0.86 and RMSE = 1.86K on October 24, 2017 at 11:30 am. The new relationships were also applied to estimate T c from T r in Hong Kong retrieved from Landsat 5 Thematic Mapper (TM) and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER). In the present climatic context, the difference between T c and T r can reach 10 K during daytime in summer, and 6 K during daytime in winter, with seasonal variation attributable to the variations in shortwave irradiance. The nighttime difference between T c and T r can also reach 2 K in both summer and spring seasons. • Parameterization of complete surface temperature over complex urban areas • Geometric effects on the difference between T r and T c were first evaluated. • Relationships between T r and T c characterized by urban geometry were developed. • Validation with high-spatial-resolution airborne thermal images was undertaken. [ABSTRACT FROM AUTHOR]

Deposition of a passivation layer on top of the perovskite is proven to be an effective method for improving the efficiency and long‐term stability of perovskite solar cells (PSCs). And the spin‐coating method is the most typical and popular method developed for this purpose. However, the spin‐coating method wastes substantial passivator materials, thus the quantitative relationship between the passivator amount and the device performance cannot be obtained. Herein, a quantitative deposition method is developed through drop‐on‐demand inkjet printing to investigate the influence of 2‐adamantylamine hydrochloride (2‐ADAHCl) deposition surface density on the device performance, which is found to have a significant impact on the device performance. A low deposition surface density of 1.1 µg cm−2 does not reach its optimum passivation capability. In contrast, an excess deposition surface density of 10.1 µg cm−2 would lead to energy level mismatch and large series resistance at the perovskite/hole transport layer (HTL) interface, thus resulting in inferior device properties. At an optimum deposition surface density of 2.5 µg cm−2, perovskite surface defects are greatly suppressed, and the interfacial contact between perovskite and HTL is improved. Finally, PSCs with a high efficiency of 24.57% are achieved with improved operational and environmental stabilities. [ABSTRACT FROM AUTHOR]

This paper aims to numerically investigate the effects of high compression ratio (CR) on the performance of ammonia-hydrogen engines. In this work, four CRs from 10.7 to 13.7 with scanning spark timing (ST) from 28°CA to 0°CA BTDC were analyzed. The main results are as follows: As the CR increases, there is a trade-off relationship between the dissipation rate of turbulence and the turbulent kinetic energy (TKE). Initially, the TKE rises as the CR increases. As the CR continues to rise, the tendency for an increase in TKE diminishes, while the turbulent dissipation rate consistently rises. Additionally, there is an escalation in heat transfer loss. Therefore, there is a trend of rising and then falling in the flow velocity and turbulence intensity with the increase of the CR. Ammonia-hydrogen flame propagation is susceptible to temperature and flow field, and a high CR can improve ignition stability, shorten combustion duration, minimize cooling loss, and enhance output power. Unfortunately, the emission of NOx gradually rises as the CR increases. At high CR, the combustion performance is optimized by adjusting ST, and the maximum IMEP and ITE are 4 bar and 38.3 %, respectively. The ST for maximum braking torque (MBT) should be gradually delayed toward TDC as the CR increases. • As the compression ratio increases, the flow velocity first rises and then decreases. • The turbulent dissipation rate increases with increasing compression ratio. • A high compression ratio improves ignition stability and combustion velocity. • The NOx gradually increases with the increase of the compression ratio. • A high compression ratio improves the power and economy of NH3-H2 engines. [ABSTRACT FROM AUTHOR]

To investigate the property of the promising and eco-friendly hydrogen-fueled rotary engine, the effect of excess air ratio on the combustion and emission characteristic of it was explored by experiment. The test was conducted under 1500 rpm and 5 CAD ADTC ignition timing. The test results demonstrated that with the decrease of excess air ratio from 2 to 0.85, the thermal efficiency of the hydrogen-fueled rotary engine increases first and then decreases. Besides, increasing MAP is beneficial to improve thermal efficiency. Among the tested condition, the highest brake thermal efficiency is realized when the rotary engine operates at 1.4 excess air ratio and 88 kPa MAP, about 18.34%. And the excellent HC and NO emissions can be obtained at the highest efficiency point. Besides, with the decrease of excess air ratio and the increase of load, the stability and flame development period gradually decrease. With a decreased excess air ratio, the flame propagation period decrease first and then increases, whereas work capacity and thermal efficiency increase first and then decrease. For NO emission, it will increase sharply near the equivalent ratio and gradually decrease after rich combustion. Also, according to the analytical model, it is found that the power performance of the rotary engine depends on the trade-off relationship of in-cylinder pressure and its angle of action. • A rotary engine was modified to run on hydrogen. • The effects of excess air ratio on combustion and emission were studied. • The best efficiency is obtained when the excess air ratio equals 1.4. • An analytical model is presented and the reasonability also be proved. • The emission corresponding to the best efficiency point is excellent. [ABSTRACT FROM AUTHOR]

Sensible heat exchange has important consequences for urban meteorology and related applications. Directional radiometric surface temperatures of urban canopies observed by remote sensing platforms have the potential to inform estimations of urban sensible heat flux. An imaging radiometer viewing the surface from nadir cannot capture the complete urban surface temperature, which is defined as the mean surface temperature over all urban facets in three dimensions, which includes building wall surface temperatures and requires an estimation of urban sensible heat flux. In this study, a numerical microclimate model, Temperatures of Urban Facets in 3-D (TUF-3D), was used to model sensible heat flux as well as radiometric and complete surface temperatures. Model data were applied to parameterize an effective resistance for the calculation of urban sensible heat flux from the radiometric (nadir view) surface temperature. The results showed that sensible heat flux was overestimated during daytime when the radiometric surface temperature was used without the effective resistance that accounts for the impact of wall surface temperature on heat flux. Parameterization of this additional resistance enabled reasonably accurate estimates of urban sensible heat flux from the radiometric surface temperature. [ABSTRACT FROM AUTHOR]

Hydrogen is a renewable fuel with excellent combustion characteristics. However, the direct use of hydrogen in existing engines faces obstacles such as abnormal combustion and high NOx emissions. This study proposes a strategy for controlling the combustion and emissions performance of a port-injection (PI) hydrogen internal combustion engine using ethanol direct injection (DI). The test conditions are 1000 rpm, 1500 rpm, and 2000 rpm respectively, the excess air coefficient is 1, 1.5, and 2, and 3%, 6%, and 9% ethanol is added. The results showed that the addition of ethanol can significantly reduce the pressure rise rate of the hydrogen engine and prolong CA0-10 and CA10-90. The addition of ethanol can promote the BMEP and BTE of the hydrogen engine. The addition of ethanol can reduce NOx emissions under lean burn conditions by 18%. The disadvantage is that the addition of ethanol increases the hydrocarbon emissions of hydrogen engines by about 50%, but the total amount is less. After the addition of ethanol, the flashback phenomenon of the hydrogen engine was significantly improved. [Display omitted] • Proposed ethanol-controlled hydrogen engine backfire strategy. • Studied the effect of ethanol addition on hydrogen engines. • The addition of ethanol increases CA0-10 and CA10-90. • The addition of ethanol improves engine BMEP and ITE. • The addition of ethanol reduces NOx emissions from hydrogen engines. [ABSTRACT FROM AUTHOR]

Syngas is a fuel with a huge market and low carbon emission, which has been proven to be well applied to internal combustion engines. WRE with high power density can effectively improve the power characteristic when syngas is employed as fuel in engines, however, which has not been reported publicly. This work aims to provide insights into the performance of syngas-fueled WRE under different CO/H2 ratios and thus gives theoretical guidance for its application. The test is done at 1500 r/min and part load. It is found that with the increase of the volumetric ratio of CO in syngas (CO%), the efficiency, torque and carbon emissions are deteriorated, however, the NO emission is significantly improved and the knock level is also reduced. In addition, on the premise of constant CO%, a high brake thermal efficiency, low NO emission and knock intensity can be achieved at lean combustion. In particular, when CO% is 10%, the combustion efficiency of CO is independent of the excess air ratio, while when CO% is 20%, that is decreased with increasing excess air ratio. In summary, the syngas-fueled WRE is recommended to adopt the qualitative control and the syngas with low CO%. • Insights into the performance of syngas-fueled Wankel rotary engines. • The trade-off relationship among power, efficiency and NO emission needs to be considered. • Qualitative control and low CO% are recommended in the syngas-fueled WRE. • The combustion efficiency of CO at varied λ is closely related to CO%. [ABSTRACT FROM AUTHOR]

Conductive graphene inks have attracted extensive research interests for printed electronics due to the excellent electrical and mechanical properties of graphene. While the traditional organic solvents used for graphene inks will result in high environmental cost, environmentally friendly solvents are required for conductive graphene inks. In this work, we demonstrate a highly conductive aqueous graphene ink printed on a paper substrate using screen printing technique. The well-tuned rheological properties of the graphene ink enable the printed lines to achieve a high resolution as fine as 45 µm in width. After being dried at 70 °C and roller compressed, the printed graphene lines present a high conductivity, up to 4.23 × 104 S m−1 at 3 µm thickness. It also shows an excellent bending stability during the roller compression process, which is compatible for large-scale manufacturing. Combining with inkjet-printed graphene oxide as the sensing layer, the graphene lines are exploited as the electrodes for a fully printed humidity sensor on the paper substrate. Such a low drying temperature, high printing resolution and low-cost printing method offers an example that two-dimensional materials are cooperatively utilized for fully printed flexible electronic devices. [ABSTRACT FROM AUTHOR]

Ammonia and hydrogen are two carbon-free alternative fuels for engines. Considering that there are few studies on improving an ammonia-hydrogen engine's lean combustion performance, this investigation based on an engine with the Miller cycle employs hydrogen direct injection (HDI) and NH 3 port injection and then proposes an adjustment strategy to vary the start of injection (SOI) of HDI for affecting the engine combustion process. When ammonia volume share (AVS) is greater than 50%, the engine shows poor performance. Nevertheless, the stratification effect of hydrogen jets may be used to elevate the hydrogen concentration around spark plug by properly delaying SOI and then creating the locally rich mixture with a high hydrogen share, which prominently promotes the flame kernel formation, shortens CA0-90, reduces C o V P m a x , and enables the engine to reach approximately 36% BTE. It is notable that very late SOI can slightly deteriorate the heat release process and lower engine performance. • Ammonia-hydrogen engines have poor combustion process under lean conditions. • A strategy to improve the lean combustion performance of the engine is proposed. • Effects of NH 3 –H 2 premixing and H 2 stratification effect on the engine are balanced. • Properly delaying SOI enhances the ignition and combustion process of the engine. [ABSTRACT FROM AUTHOR]

The non‐radiative recombination at the interfaces of perovskite solar cells (PSCs) is a crucial issue that limits the efficiency and stability of the devices. State‐of‐the‐art surface passivation strategies usually utilize alkyl ammonium halides to suppress the non‐radiative recombination of PSCs, but their high surface reactivity leads to the transformation into 2D perovskites under working conditions, limiting the passivation effect and the charge transport of PSCs. Herein, a non‐halide ionic salt 1‐naphthylmethylammonium formate (NMACOOH) is synthesized for surface passivation of perovskite films. In contrast to the traditional 1‐naphthylmethylammonium iodide, NMACOOH treatment hinders the formation of 2D perovskite and forms a thermally stable PbI2‐NMACOOH adduct on the perovskite surface. Surface characterization reveals that NMA+ can passivate the cation vacancies of the 3D perovskite while HCOO− passivates the metallic Pb0 and halide‐vacancy defects. Therefore, the non‐radiative recombination of PSCs is dramatically suppressed and a high open‐circuit voltage of 1.19 V is obtained. Finally, PSCs with high efficiency of 24.75% and improved long‐term stability (98% of the initial efficiency after 1800‐h storage) are obtained. Moreover, the NMACOOH‐passivated devices also show robust operational stability, retaining 83% of the initial efficiency after working for 658 h under continuous one‐sun illumination. [ABSTRACT FROM AUTHOR]

• The application of O 2 enrichment in a hydrogen Wankel rotary engine is assessed. • O 2 enrichment can improve power output with penalties in efficiency and emission. • O 2 -enriched level can effectively accelerate the heat release process. • O 2 enrichment will lead to knock, backfire and pre-ignition. • Low O 2 -enriched levels has higher application value than high O 2 -enriched levels. Hydrogen-fueled Wankel rotary engines (WREs) with excellent dynamic and emission characteristics have the potential to become a substitute for current fossil-fueled reciprocating piston engines. Oxygen enrichment can be employed to solve the lower power of hydrogen-fueled internal combustion engines, however, it has not been applied in hydrogen-fueled WRE at present. Hence, the goal of this work is to experimentally assess the application of oxygen enrichment in the hydrogen-fueled WRE. This work is conducted at 1500 r/min, wide-open throttle and 2.0 excess air ratio. The work found that within the test range, oxygen enrichment can effectively improve the brake torque of hydrogen-fueled WRE, however, penalize the brake thermal efficiency and NO emission. When the oxygen fraction in air increases from 21% to 29.1%, the brake torque is increased by about 45% while the brake thermal efficiency is lowered by about 8.5% and NO emission deteriorates by three orders of magnitude. Oxygen enrichment can accelerate flame development and propagation process. Besides, as the oxygen-enriched level is increased, abnormal combustion, including knock, backfire and pre-ignition, began to occur and affected the normal operation of hydrogen-fueled WRE. In general, compared with the high oxygen-enriched level, which has severe penalties on performance except for power output, low oxygen-enriched level has higher application potential. [ABSTRACT FROM AUTHOR]

Variable valve timing (VVT) and Miller cycle are advanced technologies employed to optimize engine performance by improving airflow exchange, which are seldom investigated based on the direct-injection (DI) hydrogen engine. The objective of this study is to assess the effects of intake valve closing (IVC) and exhaust valve opening (EVO) timing on the gas exchange performance, combustion, and emissions of a DI hydrogen engine, after which a synergistic control strategy of IVC and EVO timing is proposed. This work is conducted under wide-open throttle and 1500 rpm. The results indicate that the synergistic control of IVC and EVO timing can increase volumetric efficiency by more than 40%, enhance gas exchange performance, shorten combustion duration, and reduce cyclic variation, resulting in approximately 43.15% brake thermal efficiency. Furthermore, brake mean effective pressure can be increased by more than 60% and NO emissions are controlled to less than 20 ppm by optimizing valve timings. • A synergistic control strategy of intake and exhaust VVT is proposed. • The airflow exchange and combustion of a DI hydrogen engine are optimized. • The regulation of valve timings can improve gas exchange performance. • The engine can reach 43.15% maximum brake thermal efficiency. [ABSTRACT FROM AUTHOR]

The catalysts for the electrooxidation of liquid fuel in the anodic electrode has severely limited the practical large-scale commercial application of fuel cells, and hence needs to be optimized. Herein, we report a facile one-pot method to successfully synthesize the sub-16 nm dendritic Pt–Cu nanocrystals (PtCu NCs) catalysts under the assistance of ultrasonic. In virtue of such dendritic structure, the alloy and electronic effects between Pt and Cu, such binary PtCu nanodendrites exhibited extremely high electrocatalytic performances towards ethylene glycol (EG) electrooxidation with the mass activity of 4259.2 mA mg −1 , 4.5 times higher than that of the commercial Pt/C. Moreover, the Pt 1 Cu 1 nanocatalysts can endure at least 500 cycles with less activity decay, demonstrating a new class of Pt-based electrocatalysts with enhanced performance for fuel cells and beyond. [ABSTRACT FROM AUTHOR]

In order to obtain the precise predicted values of methane/hydrogen/air burning velocities from simulations, the performances of GRI mech 3.0, Aramco mech 1.3, USC mech 2.0 and San diego mech mechanisms were systematically studied under various conditions by PREMIX code and compared with experimental data from literature. The conditions where each mechanism gave their good performance are obtained and concluded. The flowrate sensitivity and rate constants of key elementary reactions were analyzed to insight the different behavior of each mechanism. The results showed that all these widely used small hydrocarbon mechanisms could gave reasonable predictions for pure methane and methane hydrogen blends. Nevertheless, they lack sensitivity for rich hydrogen at elevated pressures due to their complex reactions competitions controlled by hydrogen sub model. USC mech 2.0 was found more suitable for being used at low hydrogen contents while San diego mech gained better results at high hydrogen contents. GRI 3.0 gave good predictions for methane hydrogen blends except for high initial pressures. Generally, Aramco mech 1.3 showed the best performance for all testing conditions. Moreover, there was relatively large deviation from the predicted results and experimental data in the transition regime where the hydrogen fractions were between 60% and 80%, it may could be optimized by tuning the rate constants of reactions. [ABSTRACT FROM AUTHOR]

This paper aims to predict the intake characteristics of a side-ported Wankel rotary engine implemented by a novel dual-layer machine learning (ML) structure. The Sobol sequence coupled with a parametric phase control model is performed to generate samples using a three-dimensional dynamic simulation model. Two ML structures are compared to determine the input features, in which the input features of structure A are the port phases, while structure B also contains the geometric features. Compared with Structure A, the regression and generalization abilities of Structure B with different ML methods are generally favorable. Based on structure B, a novel dual-layer structure prediction model is developed using the Gaussian process regression method in which geometric features are used as intermediate variables. The results show that for the prediction of intake loss and volumetric efficiency, the coefficients of determination are greater than 0.99, and the prediction error is less than 1%. In addition, the port full closing timing determines the intake characteristics compared with other port phases. This paper provides novel solutions for predicting intake characteristics to guide practical optimization. [ABSTRACT FROM AUTHOR]