Original Level Research Articles

WLP-VBL: A Robust Lightweight Model for Water Level Prediction

Accurate and reliable water level prediction plays a crucial role in the optimal management of water resources and reservoir scheduling. Water level data have the characteristics of volatility and temporality; a single water level prediction model can only be applied to specific hydrological conditions and reservoirs. Therefore, in this paper, we present a robust lightweight model for water level prediction, namely WLP-VBL, by using a combination of VMD, BA, and LSTM. The proposed WLP-VBL model consists of three steps: first, the water level dataset is decomposed by EMD to obtain a number of decomposition layers K, and then VMD is used to decompose the original water level dataset into K intrinsic modal functions (IMFs) to produce a clearer signal. Next, the IMF data are sent to an LSTM neural network optimized by BA for prediction, and finally each component is superimposed to obtain the predicted value. In order to evaluate the effectiveness of the model, experiments were carried out on water level data for the Gan River. The results indicate that: (1) Compared with state-of-the art methods, e.g., LSTM, VMD-LSTM, and EMD-LSTM, WLP-VBL exhibited the best performance. The MSE and MAE of WLP-VBL decreased by 69.6~74.7% and 45~98.5%, respectively. (2) The proposed model showed stronger robustness for water level prediction, and was able to handle highly volatile and noisy data.

Numerical Research on Effects of Variable Port Timing on Performance of Marine Low-Speed Two-Stroke Engine

Enhancing the effective expansion ratio to further improve the fuel consumption, this study implemented a kind of Variable Port Timing (VPT) by designing a vertically moving sleeve on the outside of the scavenging port of a low-speed two-stroke diesel engine with a 340 mm bore. A 3D Computational Fluid Dynamics (CFD) model was constructed and calibrated to investigate the influence of the VPT strategy on the engine performance and the internal gas exchange process. The results indicated that the VPT can reduce the negative work from the compression stroke and increase the expansion work from the expansion stroke, which effectively enhances the fuel economy. However, the reduction in the mass flow rate would lead to the severe deterioration of the turbocharging system’s performance. The related matching analysis between the sleeve and the scavenging ports revealed that the sleeve velocity had a minimal influence on the scavenging flow rate, while increasing the height of the scavenging port can restore a certain mass flow rate, but will decrease the in-cylinder swirl intensity, deteriorating the combustion in the cylinders. The optimal approach is to raise the position of the scavenging port, achieving a Scavenging Port Closing (SPC) at a 235°CA, which will restore the scavenging flow rate of the original level to 90.7% and improve the indicated fuel consumption by 2.9 g/kWh.

Reconstructing the cytokine view for the multi-view prediction of COVID-19 mortality

BackgroundCoronavirus disease 2019 (COVID-19) is a rapidly developing and sometimes lethal pulmonary disease. Accurately predicting COVID-19 mortality will facilitate optimal patient treatment and medical resource deployment, but the clinical practice still needs to address it. Both complete blood counts and cytokine levels were observed to be modified by COVID-19 infection. This study aimed to use inexpensive and easily accessible complete blood counts to build an accurate COVID-19 mortality prediction model. The cytokine fluctuations reflect the inflammatory storm induced by COVID-19, but their levels are not as commonly accessible as complete blood counts. Therefore, this study explored the possibility of predicting cytokine levels based on complete blood counts.MethodsWe used complete blood counts to predict cytokine levels. The predictive model includes an autoencoder, principal component analysis, and linear regression models. We used classifiers such as support vector machine and feature selection models such as adaptive boost to predict the mortality of COVID-19 patients.ResultsComplete blood counts and original cytokine levels reached the COVID-19 mortality classification area under the curve (AUC) values of 0.9678 and 0.9111, respectively, and the cytokine levels predicted by the feature set alone reached the classification AUC value of 0.9844. The predicted cytokine levels were more significantly associated with COVID-19 mortality than the original values.ConclusionsIntegrating the predicted cytokine levels and complete blood counts improved a COVID-19 mortality prediction model using complete blood counts only. Both the cytokine level prediction models and the COVID-19 mortality prediction models are publicly available at http://www.healthinformaticslab.org/supp/resources.php.

Feedback Control in Swedish Multi-Family Buildings for Lower Energy Demand and Assured Indoor Temperature—Measurements and Interviews

Europe needs to save energy, and lowered indoor temperature is frequently promoted as part of the solution. To facilitate this, heating control systems with feedback from indoor temperature sensors are often required to avoid thermal discomfort and achieve long-term temperature reductions. This article describes a measurement- and interview-based study on feedback control where 107 Swedish multifamily buildings were analysed. The obtained results show that buildings with lowered indoor temperatures had reduced annual heating demand by 4 kWh/m2 and a reduced indoor temperature of 0.4 °C. There were, however, significant individual differences and even buildings with increased indoor temperatures, which harmed the energy savings. Temperature fluctuation was most often significantly reduced, but the impact on heating power demand during cold weather was, on average, only 2%. An interview with different actors indicated higher energy savings, possibly due to their stock’s original room temperature levels. Several interviewees also mentioned other advantages of temperature mapping. Most of the results obtained in this study were in line with several previous investigations. The study’s novelty lies in the large number of investigated buildings with mature commercial heat control technology, including PI-control for adjusting supply temperature, indoor temperature sensors in almost every apartment and a parallel analysis of additional affected parameters.

Analysis of the Current Situation of China's Catering Industry under the Background of Covid 19

Under the attack from Covid-19, there has been a significant drop in Chinese catering industry. This article carefully studied the impact of COVID-19 on China's food business by applying data and literature analysis, in order to properly deal with the shock of COVID-19 and its following effects, as well as to support the stable and healthy growth of the food industry. The new Covid-19 virus has caused a lot of trauma to the Chinese catering industry, causing China's total catering revenue fell below 4 trillion yuan. But at the same time, some companies persisted and even performed better. The aim of this research is to find the reasons for why those companies had operating issues, and find solutions to resolve the problems. Data from different authorized sources is analyzed to find the trend of the changes. Opinions from published articles are also considered and evaluated. As the result of the study, it is concluded that the impact of the new Covid-19 virus on the Chinese catering industry is undoubtedly a big one, but as long as companies have reasonable countermeasures, they can survive the difficulties safely, and even improve the original level. With the development of the epidemic, these enterprises will become more and more mature. Based on this result, the Chinese catering industry should encourage more innovation and technology improvement to survive under such conditions.

Improvements in the Electrochemical Performance of Sodium Manganese Oxides by Ti Doping for Aqueous Mg-Ion Batteries.

In recent times, the research on cathode materials for aqueous rechargeable magnesium ion battery has gained significant attention. The focus is on enhancing high-rate performance and cycle stability, which has become the primary research goal. Manganese oxide and its derived Na-Mn-O system have been considered as one of the most promising electrode materials due to its low cost, non-toxicity and stable spatial structure. This work uses hydrothermal method to prepare titanium gradient doped nano sodium manganese oxides, and uses freeze-drying technology to prepare magnesium ion battery cathode materials with high tap density. At the initial current density of 50 mA g-1 , the NMTO-5 material exhibits a high reversible capacity of 231.0 mAh g-1 , even at a current density of 1000 mA g-1 , there is still 122.1 mAh g-1 . It is worth noting that after 180 cycles of charging and discharging at a gradually increasing current density such as 50-1000 mA g-1 , it can still return to the original level after returning to 50 mA g-1 . Excellent electrochemical performance and capacity stability show that NMTO-5 material is a promising electrode material.

Pepper mild mottle virus can infect and traffick within Nicotiana benthamiana plants in non-virion forms

Virions are responsible for the long-distance transport of many viruses, such as Pepper mild mottle virus (PMMoV). Emerging evidence indicates viral traffic in the form of ribonucleoprotein complexes (RNP), yet comprehensive analysis is scarce. In this study, we inoculated plants with PMMoV-GFP, both with and without the coding sequence for the coat protein (CP). PMMoV-GFP was detected in systemic leaves, even in the absence of the CP, despite the presence of much smaller infection areas. Moreover, using leaf extracts from PMMoV-infected plants to perform a root-irrigation experiment, we confirmed that PMMoV can infect plants through root transmission. Diluting the leaf extracts significantly diminished infectivity, and attempts to compensate for the dilution of other components by adding virions above the original level proved ineffective. Our findings strongly indicate that PMMoV can infect and traffick within plants in non-virion forms. Future studies should aim to identify the specific forms involved.

High storage and operational stability self-powered UV photodetector based on p-CuI/n-GaN heterojunction prepared by thermal evaporation method

Self-powered ultraviolet (UV) photodetectors play an important role in environmental monitoring, aerospace and other fields because of the advantage of effective light response without an external power supply. Herein, a p-CuI/n-GaN heterojunction UV photodetector with self-powered function is constructed by vacuum thermal evaporation method. At 365 nm UV irradiation, the photodetector has an on/off ratio of 7536, a large photocurrent (∼35 mA) and a fast response time (rise/decay time of 10.46/10.35 ms) at zero bias. There was no significant decrease in photocurrent during the 100 on/off cycles of the continuous test, and the photocurrent of the photodetector can maintain 93.17% of the initial value after continuous operation for 15 h without bias voltage. The rise in ambient temperature exhibits a negative effect on the UV photodetector, but when it is naturally cooled from 80℃ to room temperature (RT), the photocurrent can restore to 95% of the original level. Furthermore, the photodetector maintains superior stability even after being stored in air for 3 months of without package. This work not only proves the controllable preparation strategy of CuI thin films, but also provides an efficient structure for self-powered UV photodetectors with high operational and storage stability.

The Effects of Organizational Social Support on Left-behind Children’s Resilience in China

Left-behind children are one of the main issues in China’s child welfare services. The change in the family environment has destroyed these children’s original levels of resilience. Hence social service and support from social organizations are needed. The study examines the impact of different types of social support social organizations provide to enhance the resilience of left-behind children in rural China. Types of social support analyzed include material, mental, informational, behavioral, and social interaction support. Data was collected from 384 rural left-behind children using a pre-coded questionnaire. Respondents were randomly selected from Guangxi, China in 2022. They had an average age of 12.781 years, with 45.83% male and 54.17% female. Multiple linear regression was used to conduct an empirical analysis of the different types of social support provided by social organizations. The results found that material, mental, informational, and behavioral support provided by social organizations had significant effects on the resilience of rural left-behind children in China. Further research should be conducted on the importance of providing material, mental, informational, and behavioral support to left-behind children to better help improve their resilience.

Prediction of behavioral MCL using electrophysiological responses in children using MED-EL implant.

The present study aimed to correlate the various electrophysiological tests of ECAP, EABR and ESRT with programming parameters. If there is a correlation between them, fitting formulae to be derived to predict programming parameters. Further this fitting formula was validated on a clinical population. 22 children between age range of 5-12 years using MED-EL implant participated study. Electrophysiological tests of Electrically evoked compound Action Potential (ECAP), Electrical Evoked Stapedial Reflex Threshold (ESRT) and Electrically Evoked Auditory Brain Stem Responses (EABR) were measured on electrodes no 1,4, 8, and 11. Based on Pearson correlation analysis, there was a moderate correlation observed between each of electrophysiological tests with MCL level. Fitting formulae of ECAP with either ESRT or EABR were found to be accurately predict the MCL level. These fitting formulae were clinically validated on 6 children using Sonata implant with OPUS 2 processor. Two new programs with MCL were predicted using combination of ECAP with EABR and ECAP with ESRT as parameters in the fitting formulae. These programs were given to the participants to use for two weeks. Predicted MCLs were found to slightly higher (about 2qu to 5qu) than original MCL level. Reliability analysis indicated that the formulae predicted MCL with good accuracy. Speech perception and sound field thresholds were measured in the participants' Everyday program and two predicted programs. When ECAP & EABR were the parameters, the predicted program had improved audibility as reflected in sound field thresholds as compared to those obtained with other two programs. Based on Freidman test, the results indicated that significantly lower thresholds were found for both ECAP & EABR, or ECAP & ESRT based programs when compared to Everyday program. However, speech perception scores were not significantly different among the program as per Freidman test. Thus, both the fitting models were clinically validated. The findings imply that it is not always advisable to run all three electrophysiological testing to predict the MCL levels in clinical population. It would save lot of time to run just two tests to predict the MCL in difficult to test population.

Ancient theatre acoustical qualities reconstruction dilemma for modern use and the international charters

PurposeThe general attitude of the ancient theatre conservation strategies and policies is still concerned primarily with their architectural physical appearance without considering their authentic scientific acoustical qualities. The paper attempts to illustrate and discuss how to enhance their acoustic heritage to arouse the audience's interest and needs. Thus, supporting their reconstruction based on recent acoustical research and community needs-related concerns and opportunities for ancient theatre's modern use.Design/methodology/approachIt is based on reviewing the main issues related to reconstruction in the international charters and conventions and how to infuse ancient theatres with their full role. It discusses the dilemma and debates regarding the theatre stage wall, colonnade (portico) restoration and anastylosis. Is it sufficient enough to recover the theatre sound volume? Or to rethink for full physical reconstructions of these missing related acoustical theatre architectural elements to their original level and layout as in ancient times in parallel to their virtual reconstruction?FindingsThe cultural significance of the authentic theatre's acoustical qualities needs to reform the conservation strategies and policies for a more flexible and resilient approach. It should be postulated, re-examined and advocated parallel to their 3D virtual reconstruction in the related international charters and conventions.Practical implicationsThe paper's implications are not immediate; it is far-reaching. It suggests the importance of acoustics in analysing historic theatre performance venues and reforming conservation strategies and approaches. This issue is especially critical for architects, conservators, the heritage community and the public audience.Originality/valueRecommendations are made for potential bold reconstruction actions that may be taken to achieve further sustainability, comfort, and permeability in modern theatre-use performances. Their physical reconstruction for improving the performance of contemporary theatre use regarding retaining the acoustic cultural significance should be more flexible and resilient in the charters.

Preliminary Study on the Effect of Intrastromal Anti-Vascular Endothelial Growth Factor Injections on Corneal Neovascularization Using Anterior Segment Optical Coherence Tomography Angiography

Background Corneal neovascularization, is a serious condition affecting large percentage of the population. Not only does corneal neovascularization decrease vision and cause corneal edema, but also, it is highly associated with graft rejections. Anti-VEGF has been used in many studies to treat corneal neovascularization with promising results. Recently, evaluation of corneal neovascularization using Optical Coherence Tomography Angiography (OCTA) has been explored and has shown to be promising. Objective To evaluate the effect of intrastromal injection of Anti-VEGF using the swept source anterior segment OCTA on corneal neovascularization. Patients and Methods This pilot study was done in a cohort, prospective manner. The study was done on 10 eyes of 10 patients with corneal neovascularization who were planned for keratoplasty or after keratoplasty. Intrastromal injection of Anti-VEGF using a 30 Gauge needle at a concentration of 5 mg/0.2 mL [2.5%] was done for patients involved in this study. OCTA was done 48 hours before injection, 1 week and 1 month after injection. OCTA images were compared to evaluate the effect of Anti-VEGF on corneal neovascularization. Results Compared with the pre-operative period, at 1 week postoperatively, 9 cases have shown decreased corneal neovascularization, with only 1 case that showed no regression and seemed to be unresponsive to the single injection of Anti-VEGF. At 1 month period, 8 cases had increased vascularization (re-vascularized), 1 case had decreased vascularization again (completely disappeared) and 1 case stayed the same with no change. Cases that have revascularized, have not returned back to the original vascularization level. Using OCTA colored, black and white images, we were able to picture blood vessels in 3-D image and detect subtle changes in corneal neovascularization. Using the OCTA cross-sectional images, we were able to estimate the vessels depths. In 6 cases, vessels were located in the posterior 25% of the cornea (Deep), in 2 cases they were located in the anterior 25 % (Superficial) and in 2 cases they were between the anterior 25 % and the posterior 25% (Mid-stromal). Vessel density was not possible to calculate in this study. Conclusion Bevacizumab intrastromal injections seem to be a very effective temporary method in decreasing corneal neovascularization despite the level of neovascularization. Repeated Bevacizumab injections might be needed to eliminate corneal neovascularization completely. Bevacizumab seems to have a peak action at 1 week period and then its effect seems to ware off gradually. OCTA was able to visualize vessels in 3-D image, even under vascularized corneal scars. OCTA was able to recognize subtle changes in corneal neovascularization, that were not visible by slit lamp.

Generative Adversarial Network-Enhanced Ultra-Low-Dose [18F]-PI-2620 τ PET/MRI in Aging and Neurodegenerative Populations.

With the utility of hybrid τ PET/MR imaging in the screening, diagnosis, and follow-up of individuals with neurodegenerative diseases, we investigated whether deep learning techniques can be used in enhancing ultra-low-dose [18F]-PI-2620 τ PET/MR images to produce diagnostic-quality images. Forty-four healthy aging participants and patients with neurodegenerative diseases were recruited for this study, and [18F]-PI-2620 τ PET/MR data were simultaneously acquired. A generative adversarial network was trained to enhance ultra-low-dose τ images, which were reconstructed from a random sampling of 1/20 (approximately 5% of original count level) of the original full-dose data. MR images were also used as additional input channels. Region-based analyses as well as a reader study were conducted to assess the image quality of the enhanced images compared with their full-dose counterparts. The enhanced ultra-low-dose τ images showed apparent noise reduction compared with the ultra-low-dose images. The regional standard uptake value ratios showed that while, in general, there is an underestimation for both image types, especially in regions with higher uptake, when focusing on the healthy-but-amyloid-positive population (with relatively lower τ uptake), this bias was reduced in the enhanced ultra-low-dose images. The radiotracer uptake patterns in the enhanced images were read accurately compared with their full-dose counterparts. The clinical readings of deep learning-enhanced ultra-low-dose τ PET images were consistent with those performed with full-dose imaging, suggesting the possibility of reducing the dose and enabling more frequent examinations for dementia monitoring.

The Role of 20-Hydroxyecdysone in the Control of Carbohydrate Levels in Drosophila melanogaster under Short-Term Heat Stress.

It is known that 20-hydroxyecdysone is one of the most important hormonal regulators of development, reproduction and adaptation to unfavorable conditions in insects. Here, we show for the first time that exogenous 20-hydroxyecdysone increases the content of two main insect carbohydrates, trehalose and glucose, in Drosophila melanogaster females both in normal conditions and under short-term heat stress. It is found that the levels of both trehalose and glucose increase after 39 min of heat exposure and return to their original levels after 1.5 h. A scheme of hormonal regulation of carbohydrate content under heat stress, involving 20-hydroxyecdysone, juvenile hormone, and dopamine, is suggested.

A Front-End Amplifier With Fast Reset Scheme for Capacitive Heart Rate Monitoring

Non-contact capacitive electrodes are a suitable choice for unobtrusive and long-term ECG/heart-rate monitoring applications, but require a front-end amplifier with large input impedance, low noise, and motion artifact (MA) reduction methods. This paper proposes a front-end amplifier structure with a fast reset scheme. It enables MA recovery prior to saturation and therefore avoids a long recovery process which may take up to several seconds and results in signal loss in typical capacitive sensing systems. A reconstruction algorithm restores the waveform and hence extends the dynamic range beyond the original saturation level. The proposed fast-reset amplifier and a conventional pseudo-resistor biased amplifier were fabricated in an 180nm CMOS technology. The electrical characterization results s how that the fast-reset version is superior to the conventional structure, by achieving an input resistance of 1.8 TΩ, a 3-100Hz 2.3 μV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rms</sub> integrated noise level with a 10 pF source impedance, and the ability to deal with MA saturation. Finally a 4-channel system employing the proposed amplifiers was built. It can successfully measure ECG R-peaks through clothes, while the fast reset scheme enables continuous detection in the presence of MAs.

Microfluidic Platform for Microparticle Fabrication and Release of a Cathepsin Inhibitor.

Cathepsins are a family of cysteine proteases responsible for a variety of homeostatic functions throughout the body, including extracellular matrix remodeling, and have been implicated in a variety of degenerative diseases. However, clinical trials using systemic administration of cathepsin inhibitors have been abandoned due to side effects, so local delivery of cathepsin inhibitors may be advantageous. In these experiments, a novel microfluidic device platform was developed that can synthesize uniform, hydrolytically degradable microparticles from a combination of poly(ethylene glycol) diacrylate (PEGDA) and dithiothreitol (DTT). Of the formulations examined, the 10-polymer weight percentage 10 mM DTT formulation degraded after 77 days in vitro. A modified assay using the DQ Gelatin Fluorogenic Substrate was used to demonstrate sustained release and bioactivity of a cathepsin inhibitor (E-64) released from hydrogel microparticles over 2 weeks in vitro (up to ∼13 μg/mL released with up to ∼40% original level of inhibition remaining at day 14). Altogether, the technologies developed in this study will allow a small-molecule, broad cathepsin inhibitor E-64 to be released in a sustained manner for localized inhibition of cathepsins for a wide variety of diseases.

Lab-scale transport and activation of peroxydisulfate for phenanthrene degradation in soil: A comprehensive assessment of the remediation process, soil environment and microbial diversity

Electrokinetic transport followed by electrical resistance heating activation of peroxydisulfate is a novel in situ soil remediation method. However, the strategy of electrokinetic transport coupled with electrical resistance heating and the comprehensive evaluation of restored soil need to be further explored. In this study, a lab-scale simulation device for in situ electrokinetic transport coupled with electrical resistance heating activation of peroxydisulfate was constructed to monitor the transport and transfer of peroxydisulfate, target pollutants, and process parameters, and the physicochemical properties and bacterial community of treated soil were evaluated. The results showed that adding 10 wt% peroxydisulfate to both the anode and cathode resulted in the optimized transfer rate and cumulative concentration of peroxydisulfate under electrokinetics. After 8 h, the cumulative concentration of peroxydisulfate reached 66.15– 166.29 mmol L−1, which was attributed to the migration of a large amount of S2O82− from the cathode to the soil under electromigration. Additionally, the anodic interfacial electric potential was improved, which was more conducive to electroosmotic transport of peroxydisulfate from the anode chamber. By alternating electrokinetic transport and electrical resistance heating activation of peroxydisulfate for two cycles, the phenanthrene degradation efficiency in four evenly distributed wells between electrodes reached 75.4 %, 87.6 %, 92.3 %, and 94.4 %. With slight variations in soil morphology and structure, the electrokinetic transport coupled with electrical resistance heating activation of peroxydisulfate elevated the soil fertility index. The abundance and diversity of bacterial communities in treated soil recovered to above the original soil level after 15 days. Our findings may support the application of electrokinetic transport coupled with electrical resistance heating activation of peroxydisulfate as a promising green ecological technology for the in situ remediation of organic-contaminated soil.

Biomimetic super slippery surface with excellent and durable anti-icing property for immovable heritage conservation

The formation and accumulation of ice on solid surface is not only a potential threat to our daily life, but also a hazard to cultural heritages, such as murals, grottoes, monuments, ancient buildings. Inspired by slippery inner surface of Nepenthes, slippery liquid-infused porous surfaces (SLIPSs) for anti-icing attract a lot of attention recently. In this work, dip-coating approach is utilized to create a hydrophobic silica layer grafted with long-chain organic molecules. After infusing the oil phase, a three-layer Nepenthes-like structure is formed. The SLIPS shows excellent anti-icing property. It reduces the ice-surface adhesion strength to 0 kPa on non-porous surface and 6.83 kPa on porous surface (sandstone from Yungang Grottoes) respectively. After 35 icing/de-icing cycles, the SLIPS still shows good anti-icing ability. Our results show that the middle long-chain organic layer not only enhances the surface hydrophobicity but also increases its affinity with the oil phase to reduce lubricating oil loss, thus increasing its anti-icing durability. When the anti-icing ability decreases with time, simple re-infusing the oil phase can easily restore the anti-icing performance to its original level. The SLIPSs prepared in this work show outstanding hydrophobicity, ice repellency, durability and satisfying water vapor permeability on treated porous sandstones, which makes it potential to protect immovable cultural heritages from ice hazard.

Synergistic enhancement of reaction and separation for a solar membrane reactor by topology optimization of catalyst bed

Enhancing separation and reaction in solar membrane reactors is critical for achieving temperature reduction and efficiency improvement. Based on the topology optimization method, this study investigates the optimal catalyst bed porosity distribution in solar methane steam reforming membrane reactor to maximize separation and reaction, while revealing the performance enhancement mechanism. The final optimized distribution exhibits a uniform high porosity distribution in the front and numerous inclined radial paths in the middle and rear, which achieves enhanced radial bidirectional transport. This bidirectional transport enhancement is the intrinsic mechanism for the synergistic effect of reactions and separations in reactor, thus enhancing comprehensive performances. The optimized porosity distributions with various original reaction levels and reactor lengths tend to be similar in topology optimization. They always improve solar membrane reactor performances, especially at lower reaction levels and longer reactors. At the original methane conversion of 0.6, the optimized solar membrane reactor has the maximum improvement with 28.9%, 42.8% and 32.0% in methane conversion, fuel efficiency and hydrogen recovery, respectively, which reaches 92.3% of the ideal performance. Moreover, higher relative improvements in overall performance of 30.9–59.0% are reached at reactor length of 3 m.

Comprehensive hydraulic performance improvement in a pump-turbine: An experimental investigation

Pumped storage power plants, which is known as only large-scale energy management equipment, plays a vital important role in energy field. Hump characteristic and S characteristic are two classical unsteady hydraulic characteristics when pump-turbine operating at turbine mode and pump mode, respectively. It has been found that these two characteristics are both strongly related to the complex vortex evolution process in vaneless region while only few papers focus on the elimination mechanism of them. In present paper, a scaled runner with optimized high-pressure side (HPS) is designed and manufactured based on multi-objective optimization process arming at eliminating unsteady characteristic, i.e. hump characteristic and S characteristic, while maintaining efficiency characteristic unchanged. Thereafter, hydraulic experiments are conducted to investigate the impact of HPS geometry on hydraulic performance (efficiency, hump margin, S margin and pressure fluctuation) of object pump turbine. The experimental results show that compared with the original runner, the weighted average efficiency for pump mode increases by 0.1% while the weighted average efficiency for turbine mode decreases by 0.1%. Moreover, the S margin increases from 76.7 m to 87.2 m and the S2 unsteady region is largely increased. The hump margin decreases a little while it can recover to the original level through increasing 0.6% of the original ratio scale. Moreover, the runner with optimized HPS can effectively reduce the pressure fluctuation amplitude in vaneless region up to 33.3% and 21.4% for turbine mode and pump mode, respectively.