Inlet Line Research Articles

Pantograph Slider Detection Architecture and Solution Based on Deep Learning.

Railway transportation has been integrated into people's lives. According to the "Notice on the release of the General Technical Specification of High-speed Railway Power Supply Safety Testing (6C System) System" issued by the National Railway Administration of China in 2012, it is required to install pantograph and slide monitoring devices in high-speed railway stations, station throats and the inlet and exit lines of high-speed railway sections, and it is required to detect the damage of the slider with high precision. It can be seen that the good condition of the pantograph slider is very important for the normal operation of the railway system. As a part of providing power for high-speed rail and subway, the pantograph must be paid attention to in railway transportation to ensure its integrity. The wear of the pantograph is mainly due to the contact power supply between the slide block and the long wire during high-speed operation, which inevitably produces scratches, resulting in depressions on the upper surface of the pantograph slide block. During long-term use, because the depression is too deep, there is a risk of fracture. Therefore, it is necessary to monitor the slider regularly and replace the slider with serious wear. At present, most of the traditional methods use automation technology or simple computer vision technology for detection, which is inefficient. Therefore, this paper introduces computer vision and deep learning technology into pantograph slide wear detection. Specifically, this paper mainly studies the wear detection of the pantograph slider based on deep learning and the main purpose is to improve the detection accuracy and improve the effect of segmentation. From a methodological perspective, this paper employs a linear array camera to enhance the quality of the data sets. Additionally, it integrates an attention mechanism to improve segmentation performance. Furthermore, this study introduces a novel image stitching method to address issues related to incomplete images, thereby providing a comprehensive solution.

Characterization of the airborne aerosol inlet and transport system used during the A-LIFE aircraft field experiment

Abstract. Atmospheric aerosol particles have a profound impact on Earth's climate by scattering and absorbing solar and terrestrial radiation and by impacting the properties of clouds. Research aircraft such as the Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR) Falcon are widely used to study aerosol particles in the troposphere and lower stratosphere. However, transporting a representative sample to the instrumentation inside the aircraft remains a challenge due to high airspeeds and changing ambient conditions. In particular, for high-quality coarse-mode aerosol measurements, knowledge about losses or enhancements in the aerosol sampling system is crucial. In this study, the sampling efficiency of the aerosol inlet aboard the Falcon research aircraft is characterized for the first time with state-of-the art in situ measurements including sizing instruments operated behind the Falcon aerosol inlet and mounted at the aircraft wing not affected by the aerosol inlet. Sampling efficiencies were derived for different true airspeed ranges by comparing the in-cabin and ”full”-size-range particle number size distributions during 174 flight sequences with a major contribution of mineral dust particles during the ”Absorbing aerosol layers in a changing climate: aging, lifetime and dynamics” project (A-LIFE). Additionally, experimentally derived Stokes numbers were used to calculate the cutoff diameter of the aerosol sampling system for different particle densities as a function of true airspeed. As expected, the results show that the velocity of the research aircraft has a major impact on the sampling of coarse-mode aerosol particles with in-cabin instruments. For true airspeeds up to about 190 m s−1, aerosol particles larger than about 1 µm are depleted in the sampling system of the Falcon during the A-LIFE project. In contrast, for true airspeeds higher than 190 m s−1, an enhancement of particles up to a diameter of 4 µm is observed. For even larger particles, the enhancement effect at the inlet is still present, but inertial and gravitational particle losses in the transport system get more and more pronounced, which leads to a decreasing overall sampling efficiency. In summary, aerosol particles are either depleted or enhanced in the Falcon aerosol inlet, whereas transport in sampling lines always leads to a loss of particles. Here, we have considered both effects and determined the cutoff diameter for the A-LIFE transport system (i.e., the sampling lines only), the cutoff diameter of the Falcon aerosol inlet (i.e., the effect of the inlet only), and the combined effect of the inlet and sampling lines.

Evaluation of one-dimensional models to predict chatter in spring-loaded pressure relief valves for gas service

Literature models proposed to avoid valve instabilities in safety valves for gas service are evaluated. The phenomena occurring during the opening of the safety valve are described to introduce possible sources of instabilities. Models from the last thirty years are classified based on the hypothesis of the source, creating the classifications balance-based and pressure wave models. The experiments used by their authors to validate the models are evaluated. A sensitivity analysis of five models is conducted based on set pressure, inlet line diameter, ratio of specific heats and moving mass. The model results are also compared to experimental data with different gases and set pressures. In all cases the trends of the balance-based models do not match that of the pressure wave models. Compared to measurements with different set pressures, none of the tested models did both match the trends and predict a reliable inlet line length. Comparing against measurements with varying set pressure, the three percent rule only predicted a reliable inlet line length in 2 out of 5 cases. The predicted increasing trend according to the three percent rule did not match the measured trend of decreasing maximum permissible inlet line length. Based on phenomena like the spindle friction and lubrication not being included as model input parameter, and authors finding non-reproducible measurement setups, it is concluded that the instability of a safety valve is a rather stochastic process without considering additional parameters throughout the lifecycle of the safety valve.

Simulation and experimental investigation of high-pressure pneumatic pilot-driven on/off valve with high transient performances for compressed air ejection

A high-pressure pneumatic pilot-driven on/off valve (HPPV) that quickly switches an air inlet line on and off was designed to meet the requirements of a compressed air ejection device with high pressure, high flow rate, and continuous ejection. An HPPV multi-physics field simulation model was established using AMESim simulation software based on the bond graph modeling approach that considered mechanical, gas flow, pipe heat exchange, and pilot valve operation, and experiments were conducted to check the simulation model accuracy. The effects of real gas thermodynamics, pipeline heat exchange, and pilot valve operation on the simulation model accuracy and those of different initial parameter conditions on the dynamic characteristics of the HPPV were investigated in the validated simulation model. The results indicated that the tolerance between simulation and experiment was less than 7.3%, so the simulation model was realistic and reliable. In addition, among the different influencing factors, the pipeline heat transfer significantly affected the simulation model accuracy, and the tolerance between the simulation results without considering the pipeline heat exchange and the experimental results exceeded 10%. The real gas thermal effect slightly affected the simulation model accuracy, and the tolerance between the simulation results under the action of each gas state equation was less than 3%. The pilot valve operation affected only the opening and closing moments of the HPPV and had no effect on the simulation model accuracy. The dynamic characteristics of the HPPV were stable and reliable under different initial parameter conditions.

Modifications to therapeutic plasma exchange to achieve rapid exchange on cardiopulmonary bypass prior to pediatric cardiac transplant.

Cardiac transplants increasingly occur following placement of ventricular assist devices (VADs). A strong association exists between human leukocyte antigen (HLA) sensitization and VAD placement; however, desensitization protocols that utilize therapeutic plasma exchange (TPE) are fraught with technical challenges and are at increased risk of adverse events. In response to increased VAD utilization in our pre-transplant population, we developed a new institutional standard for TPE in the operating room. Through a multidisciplinary effort, we developed an institutional protocol for intraoperative TPE immediately prior to cardiac transplantation after cannulation onto cardiopulmonary bypass (CPB). All procedures used the standard TPE protocol on the Terumo Optia (Terumo BCT, Lakewood, CO, USA), but incorporated multiple modifications to limit patients' bypass times, and to coordinate with the surgical teams. These modifications included deliberate misidentification of replacement fluid and maximization of the citrate infusion rate. These adjustments allowed the machine to run at maximal inlet speeds, minimizing duration of TPE. To date, 11 patients have been treated with this protocol. All survived their cardiac transplantation operation. Hypocalcemia and hypotension were noted; however, none of these adverse events appeared to have clinical impact. Technical complications included unexpected fibrin deposition in the TPE circuit and air in the inlet line due to surgical manipulation of the CPB cannula. No thromboembolic complications occurred in any patient. We feel that this procedure can be rapidly and safely performed in HLA sensitized pediatric patients on CPB to limit the risk of antibody mediated rejection of their heart transplant.

Influence of ozone and humidity on PTR-MS and GC-MS VOC measurements with and without a Na2S2O3 ozone scrubber

Abstract. The measurement of volatile organic compounds (VOCs) can be influenced by ozone (O3), resulting in sampling artefacts that corrupt the data obtained. Published literature reports both positive (false enhancements of signal) and negative (loss of signal) interference in VOC data due to ozonolysis occurring in the sample gas. To assure good data quality it is essential to be aware of such interfering processes, to characterize them and to try to minimize the impact with a suitable sampling setup. Here we present results from experiments with a sodium thiosulfate ozone scrubber (Na2S2O3), which is a cost-effective and easily applied option for O3 scavenging during gas-phase sampling. Simultaneous measurement of selected organic trace gases using gas chromatography–mass spectrometry and proton transfer reaction–mass spectrometry was performed at different ozone levels (0–1 ppm) and different relative humidities (0 %–80 %). In this way both tropospheric and stratospheric conditions were examined. The measured data show that several carbonyl compounds including acetaldehyde, acetone and propanal show artificial signal enhancement when ozone is present at higher concentrations (> 150 ppb) in dry air, while analytes with double bonds like isoprene (measured with GC-MS) and terpenes show lower signals due to reaction with ozone. Both effects can be eliminated or in the case of sesquiterpenes substantially reduced by using Na2S2O3 impregnated quartz filters in the inlet line. With the chosen scrubbing material, relative humidity (RH) substantially improves the scrubbing efficiency. Under surface conditions between 50 %–80 % RH, the filter allows for accurate measurement of all species examined.

Thermal Atomic Layer Etching of CoO, ZnO, Fe2O3, and NiO by Chlorination and Ligand Addition Using SO2Cl2 and Tetramethylethylenediamine

Thermal atomic layer etching (ALE) of CoO, ZnO, Fe2O3, and NiO was achieved using chlorination and ligand-addition reactions at 250 °C. This two-step process was accomplished by first chlorinating the metal oxide with SO2Cl2. Subsequently, ligand addition to the metal chloride was performed using tetramethylethylenediamine (TMEDA). In situ quadrupole mass spectrometry (QMS) studies on metal oxide powders revealed that CoO, ZnO, Fe2O3, and NiO all formed stable and volatile MCl2(TMEDA) compounds (M = Co, Zn, Fe, Ni) as etch products at 250 °C. These QMS studies of the sequential SO2Cl2 and TMEDA exposures were facilitated by a new reactor design with two nested inlet lines that transport the reactants separately to the powder substrate. The time-dependence of the reactants and products could also be monitored by the QMS investigations. The large SO2+ ion intensity observed at the beginning of the SO2Cl2 exposure was consistent with the chlorination reaction MO + SO2Cl2 → MCl2 + SO2 + (1/2)O2. The time-dependent QMS studies also observed the MClx(TMEDA)+ ion intensity peaking at the beginning of the TMEDA exposures. The subsequent decay of the MClx(TMEDA)+ ion intensity, while the (TMEDA)+ ion intensity remained constant, was evidence for a self-limiting ligand-addition reaction. The mass loss of the metal oxide powders was confirmed after sequential SO2Cl2 and TMEDA exposures. The etching of two of these metal oxides was also verified using separate experiments on flat substrates using SO2Cl2 and TMEDA exposures at 250 °C. For CoO thermal ALE, an etch rate of 4.1 Å/cycle at 250 °C was measured using X-ray reflectivity (XRR) studies. For ZnO thermal ALE, an etch rate of 0.12 Å/cycle at 250 °C was measured using quartz crystal microbalance (QCM) investigations. Other first row transition metal oxides were surveyed in addition to CoO, ZnO, Fe2O3, and NiO. QMS studies of TiO2, Cr2O3, and MnO2 showed no volatile species formation during sequential SO2Cl2 and TMEDA exposures at 250 °C. In contrast, V2O5 and CuO were spontaneously etched using SO2Cl2 at 250 °C, as determined by the observation of volatile VOCl3 and CuCl3 etch products, respectively. Calculated Gibbs free energy changes for the various etching reactions also supported the experimental observations for the first row transition metal oxides. These studies illustrate that the chlorination and ligand-addition reaction mechanism can provide a new avenue for the thermal ALE of a variety of transition metal oxides that have nonvolatile metal chlorides.

Development of tin copper alloys in shell and tube evaporator heat exchanger systems in ocean thermal energy converse power plant

A case study of the manufacture of an OTEC factory on a floating ship has been carried out using 100 MW Titanium material at a fairly expensive cost, so the OTEC system was researched using a copper-tin alloy. The behavior of the tin-copper heat exchanger between the Aspen Plus simulation and the Computational Fluid Dynamics (CFD) simulation on Shell And Tube evaporators of Bonnet Divided Flow fixed and Bonnet One-pass Shell fixed (BEM) types is investigated. The difference in temperature between water at sea level of 29 °C and water at a depth of 1000 meters at a temperature of 5 °C is assumed to produce electricity. A marine thermal energy conversion power plant is a continuous source of energy sourced from nature an evaporator heat exchanger with ammonia working fluid will produce power that can drive a turbine forwarded to a generator. The simulation results of CFD of a Bonnet Divided Flow fixed type Heat Exchanger on the hot water inlet line has a temperature of 29.9 °C, when exiting the evaporator shell the temperature decreases to 26.4 °C. At the inlet line, the working fluid of ammonia enters the evaporator at 7.9 °C and when it leaves the tube, the temperature rises to 26.3 °C. The best results of the simulation of Aspen Plus Heat Exchanger type BEM Inlet Ammonia temperature 8 °C and at CFD 7.99 °C. Meanwhile, at the ammonia outlet at 28 °C and in the CFD simulation, the ammonia outlet temperature was 28.21 °C. Aspen Plus Inlet heating water temperature is 30 °C, and in CFD simulation, the temperature is 29.99 °C. While the heating water outlet is 28 °C, and in the CFD simulation, the heating water outlet is 28.15 °C. The conclusion from the simulation results is that the BEM-type heat exchanger is very good and suitable for experimental prototyping.

Safety and Effectiveness of Veno-Venous Extracorporeal Membrane Oxygenation Combined With Continuous Renal Replacement Therapy.

Patients receiving extracorporeal membrane oxygenation (ECMO) often suffer from acute kidney injury (AKI), requiring continuous renal replacement therapy (CRRT). In our clinical practice, we connected the inlet line of a CRRT machine to the postoxygenator Luer port and the outlet line to the inlet Luer port of the oxygenator. In this case series, we analyzed the interaction between the two machines. Between December 31, 2017, and December 31, 2019, we enrolled 15 patients from the ICU of the San Matteo Hospital, Pavia, Italy. All of them suffered from severe acute respiratory distress syndrome and AKI stage 3. We analyzed 570 hours of CRRT combined with venovenous ECMO and collected 261,751 CRRT data. No discontinuation of CRRT occurred before 48 hours. Most of the alarms occurred within 24 hours of the connection: 22/10,831 (0.2%) showed an outranged inlet pressure, 11/10831 (0.11%) showed an outranged transmembrane pressure, 14/10,831 (0.13%) showed an outranged inlet pressure, and 138/10,831 (1.27%) an outranged effluent pressure. The rate per minute set for the ECMO circuit was correlated with the inlet (β = 5.38; CI, 95% 1.42-9.35; p = 0.008), transmembrane (β = 4.6; CI, 95% 1.97-7.24; p = 0.001), effluent (β = 3.02; CI, 95% 1.15-4.90; p = 0.002), and outlet pressures (β = 597; CI, 95% 2.31-9.63; p = 0.001) of the CRRT circuit. We reported that our configuration could be safe and effective, however well-designed studies would be beneficial for determining the potential risks and benefits.

(Student Award, 1st Place, Invited) Thermal Etching of Metal Oxides: Mechanisms Revealed By Quadrupole Mass Spectrometry

Thermal etching of metal oxides can occur spontaneously or by sequential surface reactions during atomic layer etching (ALE). This thermal etching does not require the use of plasmas or energetic species to remove material. Thermal etching can be studied by measuring the decrease of film thickness. However, the mechanisms of thermal etching still require the identification of volatile etch products. To address this issue, we have used quadrupole mass spectrometry (QMS) to detect volatile etch products during thermal etching. A custom reactor was built to measure the etch products with high sensitivity. This reactor uses molecular beam techniques to direct the etch products with line-of-sight to the QMS ionizer. Figure 1 shows a schematic of the QMS reactor. Nested inlet lines allow two reactants to be transported to the sample holder.This talk will explore the thermal etching of metal oxides using three different approaches: (1) chlorination followed by ligand addition; (2) exposure to acetylacetone; and (3) fluorination followed by ligand exchange or conversion. For the first approach, chlorination followed by ligand addition will be utilized for CoO thermal ALE with SO2Cl2 as the chlorination reactant and tetramethylethylenediamine (TMEDA) as the ligand-addition reactant at 250°C. The proposed mechanism for CoO thermal ALE is shown in Figure 2. SO2Cl2 converts the CoO surface to a CoCl2 layer and yields SO3. Then the TMEDA adds to CoCl2 and forms volatile CoCl2(TMEDA) etch products. QMS studies were able to confirm the formation of CoCl2(TMEDA) etch products. Figure 3 displays the CoCl2(TMEDA) etch products observed for the 5th CoO ALE cycle during the TMEDA exposure at 250°C. The natural abundance of the Cl isotopes affirmed that CoCl2(TMEDA) was the volatile etch product.Additional time-resolved experiments were able to monitor the reactants and volatile etch products. Figure 4 displays the ion intensities of C3N8N+ (largest crack of TMEDA) and CoCl(TMEDA)+ (largest crack of CoCl2TMEDA) during the TMEDA exposure at 250°C. The self-limiting nature of the ligand-addition reaction is revealed by the decrease of the CoCl(TMEDA)+ ion intensity with time while the TMEDA ion intensity remains constant. Chlorination followed by ligand addition was also utilized for the thermal ALE of other first row transition metal oxides (Fe2O3, NiO, and ZnO). M(TMEDA)Cl2 was observed as the volatile etch product for M= Fe and Ni. Zn(TMEDA)Cl was observed for ZnO.For the second approach, acetylacetone (Hacac) and hexafluoroacetylacetone (Hhfac) have been known to spontaneously etch a variety of metal oxides including ZnO, CuOx and Fe2O3. In addition, some thermal ALE procedures have been developed using Hacac together with an oxidation reactant to clean the metal oxide surface after the Hacac exposure. This talk will highlight results for ZnO etching using sequential Hacac and O3 exposures and also consecutive Hacac exposures. Zn(acac)2 was observed by the QMS studies during the alternating Hacac and O3 exposures on ZnO throughout the Hacac exposures at 250°C. Additional experiments using Hacac exposures with no O3 exposures also observed the continuous yield of Zn(acac)2. These experiments provide evidence for the spontaneous etching of ZnO by Hacac according to the reaction: ZnO + 2Hacac -> Zn(acac)2 +H2O. This reaction is believed to proceed spontaneously through a ligand substitution/hydrogen transfer mechanism. Other metal oxides were also etched using sequential Hacac and O3 exposures including V2O5, Fe2O3, CoO and CuO at 250°C. M(acac)2 species were observed for M=Co, Fe and Cu. VO(acac)2 was observed for V2O5.Lastly, for the third approach, Al2O3 thermal ALE was explored using sequential BCl3 and HF exposures at 300°C. This thermal ALE process could occur by (A) conversion of Al2O3 to B2O3 by BCl3 followed by the spontaneous etching of B2O3 by HF or (B) fluorination of Al2O3 to AlF3 followed by the ligand exchange of AlCl3 with BCl3 to produce volatile AlCl3. QMS analysis revealed that initial exposures of BCl3 on Al2O3 led to a conversion reaction forming B2O3 and volatile AlCl3. Subsequently, the HF exposure on B2O3 released BF3 and H2O. After removing the B2O3 conversion layer, the HF proceeded to fluorinate Al2O3 to form a AlF3 layer and volatile H2O. Additional BCl3 exposures then underwent ligand exchange with the AlF3 layer to form BFCl2 and AlCl3. The BCl3 continued to convert the underlying Al2O3 to B2O3. Moreover, the BCl3 exposures were also observed to spontaneously etch the B2O3 conversion layer. QMS studies revealed that the reaction of BCl3 with the B2O3 conversion layer or initial B2O3 substrates produced B3O3Cl3, a boroxine ring species. BCl3 has the unusual ability to convert Al2O3 to B2O3 and then spontaneously etch the B2O3. Figure 1

An experimental and numerical investigation into using hydropower plant on oil transmission lines

AbstractReplacing control valves in the inlet lines of oil transmission stations with hydropower plants can be a logical solution to convert energy losses into useful power. In this regard, this paper carried out an experimental and numerical investigation to study the feasibility of applying a pump as turbine in a hydropower system and its performance on the oil transmission lines. An experimental platform, comprising a tank, hydropower, centrifugal pump, electromotor, and measuring instruments, was constructed. An external gear pump was employed regarding the high working pressure of the system, maximally 80 bar, as an actuator of the centrifugal pump. By comparing the efficiency of the electropump with the hydropower‐driven pump, it was observed that maximum efficiency, approximately 20.6%, occurred when the pump reached its best efficiency point. Furthermore, based on experiments on hydropower‐driven pump under different inlet pressures, an optimal point was observed for the system. This issue enhanced the system's efficiency by 19% as the flow rate increased by 1.9 L/s in the inlet pressure of 80 bar. According to the results, as the flow rate increases, there is a descending trend in outlet pressure. Besides this, there is an optimum condition for the maximum efficiency of hydropower plants and this crucial point should be determined by experimental or numerical studies to reach maximum performance. Furthermore, extracted values of power from the computational fluid dynamics model were compared with the experiments with less than 8% error in most cases. Therefore, a correlation was introduced for the prediction of power based on effective parameters of outlet pressure and volumetric flow rate for the off‐design condition in each inlet pressure with roughly 2% error.

Thermal‐hydraulic investigation of a proposed concept for a passive containment cooling system and evaluation of heat exchanger performance

Reduction in ambient pressure within the containment of a light water reactor in the event of a hypothetical Loss of Coolant Accident (LOCA) is crucial for containment integrity. This article introduces the distinct concept of a Passive Containment Cooling System (PCCS). In the proposed PCCS concept, the containment is divided into two compartments with appropriate volumes. An external heat exchanger is connected between the two compartments of the containment for heat transfer and pressure reduction in the case of LOCA. This concept has unique characteristics and provides many advantages over previous designs. A RELAP5 model was developed to perform thermal-hydraulic analysis of the proposed PCCS concept. The performance of the PCCS after its deployment on a small reactor (998.6 MWth) has been assessed under various conditions following LOCA. The results indicate that partitioning of the containment creates a differential pressure that acts as a driving force for flow through the PCCS heat exchanger. Consequently, a decrease in long-term containment pressure is observed. In the case of equal volume fractions in the two containment compartments, the PCCS reduces long-term pressure in the containment by 16.5%. Sensitivity analysis was conducted in which the flow area of the PCCS inlet line, the heat transfer area, and the size of the heat exchanger tank were varied. The PCCS heat transfer capacity increases as these parameters are increased. However, the former is less sensitive than the latter two. The performance of the PCCS heat exchanger under steady-state conditions was validated using RELAP5 simulations, empirical correlations, and analytical models. The evaluation of heat exchanger parameters by various methods (presented in Appendix 1 ) was found in close agreement.

A novel approach for adapting the standard addition method to single particle-ICP-MS for the accurate determination of NP size and number concentration in complex matrices

This paper presents a novel approach, based on the standard addition method, for overcoming the matrix effects that often hamper the accurate characterization of nanoparticles (NPs) in complex samples via single particle inductively coupled plasma mass spectrometry (SP-ICP-MS). In this approach, calibration of the particle size is performed by two different methods: (i) by spiking a suspension of NPs standards of known size containing the analyte, or (ii) by spiking the sample with ionic standards; either way, the measured sensitivity is used in combination with the transport efficiency (TE) for sizing the NPs. Moreover, such transport efficiency can be readily obtained from the data obtained via both calibration methods mentioned above, so that the particle number concentration can also be determined.The addition of both ionic and NP standards can be performed on-line, by using a T-piece with two inlet lines of different dimensions. The smaller of the two is used for the standards, thus ensuring a constant and minimal sample dilution. As a result of the spiking of the samples, mixed histograms including the signal of the sample and that of the standards are obtained. However, the use of signal deconvolution approaches permits to extract the information, even in cases of signal populations overlapping.For proofing the concept, characterization of a 50 nm AuNPs suspension prepared in three different media (i.e., deionized water, 5% ethanol, and 2.5% tetramethyl ammonium hydroxide-TMAH) was carried out. Accurate results were obtained in all cases, in spite of the matrix effects detected in some media. Overall, the approach proposed offers flexibility, so it can be adapted to different situations, but it might be specially indicated for samples for which the matrix is not fully known and/or dilution is not possible/recommended.

Optimization of the outlet unloading structure to prevent gaseous cavitation in a high-pressure axial piston pump

Raising the pressure rank of axial piston pumps is an effective way to enhance the power density. However, when hydraulic fluid switches between the suction and discharge areas in the valve plate at a high level of pressure, the effective delivery flow rates of pumps decrease and may cause vibrations, noise and gaseous cavitation. Increasing the inlet pressure is a common method used to reduce gaseous cavitation; however, this requires additional equipment to pressurize the inlet line, which reduces the power density of the pump. This study proposed a new approach to reduce gaseous cavitation by modifying the shape of the unloading holes for pumps. A computational fluid dynamics (CFD) model was established to examine the influences of the unloading holes of the valve plate on gaseous cavitation. The simulation results revealed that a crescent-shaped unloading hole in the valve plate can effectively decrease the gaseous cavitation by redistributing the damage power of cavitation. Moreover, the crescent-shaped design of the unloading hole can increase the unloading rate by 64.39% at an inlet pressure of 1.1 MPa and rotational speed of 1600 r/min compared to that of traditional unloading holes. As a result, cavitation in the pump can be reduced effectively by an improved unloading rate, which has great practical significance for suppressing the cavitation phenomenon and decreasing vibration and noise in the pump.

Heterogeneous nitration reaction of BSA protein with urban air: improvements in experimental methodology.

Gas-phase ozone (O3) and nitrogen dioxide (NO2) can react with environmentally exposed proteins to induce chemical modifications such as the formation of nitrotyrosine (NTyr). Certain proteins with these modifications have also been shown to promote adverse health effects and can trigger an immune response. It is hypothesized that proteinaceous material suspended in the atmosphere as particulate matter, e.g., embedded in pollen, can undergo heterogenous reactions to produce chemically modified proteins that impact human health, especially in urban areas. To investigate the protein modification process under ambient outdoor reaction conditions, bovine serum albumin (BSA) protein samples were loaded onto filters and exposed to urban air in Denver, Colorado (USA). Losses and measurement artifacts were measured independently to calculate nitration effects on the protein via high-performance liquid chromatography and to support the experimental methodology. O3 loss from inlet lines using three commonly used particulate filters was quantified, showing a range of ambient O3 concentration losses from 3.2% for Kynar® (polyvinylidene fluoride) filters to > 60% for commonly used HEPA filters. Protein mass extraction efficiency was calculated as a function of filter material and protein mass using both native and nitrated BSA. Finally, we show examples of BSA samples nitrated by exposure to urban air as a proof-of-concept for future studies, highlighting the potential for atmospherically relevant NTyr formation. The methodology vetted here provides support for a wide variety of experimental efforts related to exposure of analytes to O3 and more broadly to an expanding field of protein modification in ambient air.

Surface roughness of Ti6Al4V samples produced by laser powder bed fusion for bone implants

This study describes the surface roughness of heat-treated Ti6Al4V ELI samples without surface finishing (as-built condition) depending on the position of the build plate. Surface roughness was studied at the top and side surfaces of horizontal and vertical samples using a profilometer and Scanning Electron Microscopy. Morphology of tested samples is shown. It was shown that the top and side surfaces of vertical and horizontal samples had different morphologies, but they had fairly close roughness values, since the formation of roughness was mainly associated with sticking of the powder material both on the upper surface of the samples and on the side surfaces. It was found that samples that were far away from the argon inlet and recoater start line had higher surface roughness.

Fault identification method for distribution network based on parameter optimized variational mode decomposition and convolutional neural network

In order to extract the fault characteristics of the distribution power system automatically, a new method for fault identification based on parameter optimized variational mode decomposition (VMD) and convolutional neural network (CNN) is proposed. First, the VMD is used to decompose electric signals of the main transformer, including the current of the low-voltage inlet line, bus voltage, and so on. The obtained intrinsic mode functions should be arranged in sequence from low to high according to the central frequency. The VMD can obtain the time-frequency matrices. In order to decide the decomposition layers of the VMD adaptively, the partial mean of multi-scale permutation entropy is used to optimize it. Then, the time-frequency matrixes can be converted into pixel matrices by pseudo-colour coding. The pixel matrices which are appropriately compressed can be used as input of CNN. The CNN can autonomously extract the eigenvectors of fault. Finally, the classification algorithms of support vector machine (SVM), naive Bayesian classifier (NBC), extreme learning machine (ELM), and random forest (RF) are used to train and test the feature vectors extracted by CNN to verify the effectiveness of the method. The experiments show that the proposed method has excellent stability, fast convergence speed, and high precision. The technique can effectively complete the fault identification of the distribution network.

Investigation of boiling heat transfer in microchannel of water and isopropanol

Boiling curves of distilled water and isopropanol in 12.5x3x0.2 mm microchannel with rigid inlet and outlet lines are obtained. Critical heat flux is calculated for isopropanol by using the previously obtained correlation for water.

Renal replacement therapy in extra-corporeal membrane oxygenation patients: A survey of practices and new insights for future studies

BackgroundPatients under extra-corporeal membrane oxygenation (ECMO) are at high risk of developing acute kidney injury and renal replacement therapy (RRT) is frequently needed. The aim of this study was to explore RRT use in ECMO patients, as no recommendations exist in this setting. MethodsAn online questionnaire about RRT management in ECMO patients was sent to the members of the ARCOTHOVA (Anesthésie-Réanimation Coeur-Thorax-Vaisseaux) association and to the GFRUP (Groupe Francophone de Réanimation et Urgences Pédiatriques). ResultsNinety intensivists from adult ICU and twenty from paediatric ICU responded to the questionnaire. RRT use was common as 67% respondents reported that more than 25% of their ECMO patients needed RRT. RRT indications were similar between centres, with persistent anuria (83%), metabolic acidosis (80%), fluid overload (78%) and hyperkalaemia (80%) being the more prevalent. Continuous renal replacement therapy was the preferred technique (97%). Continuous veno-venous haemofiltration was predominant (64%) over continuous veno-venous haemodiafiltration (21%). Unfractionated heparin was employed as first line choice anticoagulation in 61% and regional citrate anticoagulation in 16%. Integration of RRT device directly into the ECMO circuit was the preferred configuration (40%) while parallel systems with separate catheter were used in 30%. When the integrated approach was chosen, RRT device was most frequently connected with inlet and outlet lines after the ECMO pump (58%) and pressure alarms were encountered for 60% of participants. ConclusionsOur results highlight the high variability of practice between centres. They suggest the need to compare the integrated and parallel configurations of combining RRT and ECMO.

Effect of Blood Flow Rate on the Accuracy of Central Venous Pressure Measurement during Continuous Renal Replacement Therapy

Background: The objective of this study was to study the influence of extracorporeal blood flow rate (BFR) on the accuracy of central venous pressure (CVP) measurement during continuous renal replacement therapy (CRRT). Methods: Eligible patients were randomly divided into 3 groups based on the location of catheters used for their CRRT and CVP measurement. CVP levels measured at increased extracorporeal BFR (from 0 to 300 mL/min) in the normal and reverse positions of inlet and outlet lines connected to the CV catheter (CVC) in the course of the CRRT session were collected. Results: CVP levels measured at different extracorporeal BFRs did not significantly differ between and among the 3 groups. Inversion of inlet and outlet lines connected to the catheters did not affect the accuracy of CVP measurement. BFR had a negative correlation with inflow/access pressure but a positive correlation with outflow/return pressure. Neither inflow pressure nor outflow pressure was correlated with CVP. Conclusions: Extracorporeal BFR has no influence on the accuracy of CVP measurement during CRRT with the net machine balance adjusted to zero regardless of the location of the catheter and the connection method between catheters and CRRT lines. Thus, CRRT does not need to be discontinued to obtain an accurate CVP measurement.