Search

Lipids play numerous pivotal physiological roles in mammalian reproduction, being indispensable for oocyte competence acquisition and post-fertilization embryonic development. Profiling lipids in minute samples, such as oocytes, presents challenges but has been accomplished through mass spectrometry technologies like Multiple Reaction Monitoring (MRM) profiling. With the dual objectives of simplifying workflow and examining the influence of preanalytical conditions, we assessed whether transportation at room temperature affects the lipid profile of bovine oocytes. To this end, samples were prepared using either monophasic (methanol only) or biphasic liquid extraction protocols (Bligh & Dyer method) and transported either on dry ice or at room temperature inside sealed-vacuum packages to prevent lipid oxidation. Subsequently, employing a comprehensive method, we screened a list of 316 MRMs from 10 different lipid subclasses in oocyte lipid extracts. Principal Component Analysis (PCA) revealed similar lipid profiles concerning temperature during transportation, whereas clear differentiation among samples was observed based on the lipid extraction method. Univariate analysis indicated that the one-phase methanol extraction resulted in higher relative abundances of phospholipids, except for phosphatidylserines. Conversely, the Bligh & Dyer extraction favored the detection of neutral intracellular lipids (triacylglycerols, free fatty acids, cholesteryl esters, and acyl-carnitines). Consequently, lipid recovery was directly correlated with the polarity of lipid class and the extraction method. Regarding transportation temperature, phosphatidylethanolamine, triacylglycerol, and free fatty acids exhibited lower abundances when samples were transported at room temperature. Based on multivariate and univariate analyses, we conclude that if samples undergo the same lipid extraction protocol and are transported in the same batch at room temperature inside vacuum-sealed bags, it is feasible to analyze lipid extracts of bovine oocytes and still obtain informative lipid profiling results. [ABSTRACT FROM AUTHOR]

Treating the high water-content sludge with vacuum-assisted prefabricated horizontal drains (PHDs) placed inside, geotextile tubes have the advantage of multiple drainage paths, and geomembrane tubes have the superiority of high vacuum maintenance. Therefore, converting the geotextile tube into a geomembrane tube during slurry dewatering is an effective measure for greater dewatering efficiency and better dehydration effect. In this study, a profound plane-strain consolidation model considering two-dimensional seepage is developed for explaining the dewatering mechanism of sludge in the geo-tubes. Analytical solutions are given and validated by the experiment. The impact of major variables on tube efficiency is further discussed to reference the practice design. Parametric analyses reveal the critical time corresponding to the optimal efficiency of the geotextile tube, after which its consolidation efficiency decreases significantly. However, the consolidation efficiency of a geomembrane tube increases throughout the duration. Consequently, a switching point corresponding to the iso-efficiency state of the geotextile tube and geomembrane tube can be determined for the tube conversion. [ABSTRACT FROM AUTHOR]

The influence of vacuum pressure applied on H2 separation from a palladium membrane is explored in this study. Three factors with three levels are considered, including the membrane chamber temperature with levels 320 °C, 350 °C, and 380 °C; the retentate-side total pressure with levels 1, 2, and 3 atm; and the permeation-side vacuum pressure with levels 0, 25, and 50 kPa. The Taguchi, response surface methodology (RSM), and multivariate adaptive regression splines (MARS) methods are employed to analyze the effects of the three parameters on hydrogen separation and predict their optimal combination. The retentate-side total pressure exhibits the highest impact on H2 permeation, following the permeation-side vacuum pressure and then the membrane chamber temperature. The maximum H2 flux is 0.226 mol∙s−1∙m−2, with H2 recovery of 91 % obtained at the optimal conditions with a temperature of 380 °C, a total pressure of 3 atm, and a vacuum pressure of 50 kPa. The improvement in H2 flux reaches 21.6 % compared with the case without the imposed vacuum pressure at the same temperature and total pressure. This result shows the imposed vacuum pressure is an efficient way to enhance H2 permeation. The maximum relative errors between the experimental data and the predictions from the Taguchi, RSM, and MARS methods are 6.74 %, 3.37 %, and 8.08 %, respectively. The RSM method presents higher accuracy than Taguchi and MARS, perhaps due to a more precise analysis of the interaction terms. The smaller amount of input data and ignoring the temperature effect in MARS could be the reason for the lower accuracy. Nevertheless, the MARS method still demonstrates acceptable results. The cost of the Taguchi method is lower than that of the RSM method since it requires fewer experimental cases. In a word, the choice of the prediction method depends on the desired accuracy and the experimental cost.

AbstractThis paper presents a novel method of treating high water content dredged slurry by vacuum pre-pressure using woven rice straw as horizontal drainage boards (SHDs). This not only helps to avoid the impact of plastic drainage boards on the environment, but also helps to utilize agricultural related waste. The study aimed to investigate the effect of SHDs degradation on the vacuum transfer within the horizontal drainage boards and the consolidation characteristics of dredged slurry. Indoor vacuum preloading model tests were conducted to investigate soil settlement, straw degradation, vacuum variation and water content distribution within the drainage board. The results show that SHDs can significantly improve the consolidation of dredged slurry. The closer the straw is to the interface between the drainage board and the vacuum pipe, the greater the degree of degradation. The water content was distributed with depth in an oblique “z” shape, while a point with higher water content existed at 1/3 of the soil above the drainage boards. In addition, the low water content zone around the drainage board shows an elliptical shape due to the influence of gravity. These research results have some reference value for the ecological treatment of dredged slurry and straw. [ABSTRACT FROM AUTHOR]

The deviation of water seepage from Darcy's law has been verified in soft soils with high compressibility. Consolidation behaviors of prefabricated vertical drains (PVD)-improved soft soils caused by non-Darcian flow have been extensively studied, but most of them are based on small-strain consolidation theory, and it is generally assumed that the discharge capacity of vertical drains keeps constant during the process of consolidation. Considering the large-strain characteristic of the soft soils with high compressibility, the consolidation model of soft soils with non-Darcian flow is established in the Lagrange coordinate system. Meanwhile, considering the poor stages of drainages such as bending and silting caused by the deformation of soil layers, the discharge capacity of vertical drains in the proposed model is regarded as changing with time and depth. The feasibility of the solution is verified by comparing the proposed results with existing solutions, and consolidation behaviors under different conditions are investigated. The results show that the influence of non-Darcian flow cannot be ignored when the ratio of the influential zone radius to the radius of vertical drains reaches 15. The common surcharge loading applied to the PVD-improved soft soils has to consider the influence of consolidation results by non-Darcian flow. The difference of vacuum pressure distribution between Darcy's flow and non-Darcian flow mainly exists in the middle and late period of consolidation. Finally, the proposed consolidation model is applied to the consolidation calculation of Brisbane Port, and the calculation results by the proposed model coincide with the field measurement. [ABSTRACT FROM AUTHOR]

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Vacuum-soaked biomass gasification is a method being developed to replace fossil fuels in a safe, simple, and reliable manner. The biomass gasification process demands high temperatures in the region of 800–1000 °C, yet even when applying vacuum pressure and soaking the biomass, the experimental results of the gasification temperature can be maintained properly. Cyclone and heat exchanger system, the reactor's syngas exit temperature, which is typically 600 °C, and may be lowered to under 50 °C. The heat exchanger's temperature profile indicates that 8 m are the most practical/ideal length. The heat exchanger's effectiveness is almost perfect (0.99) and higher than in earlier experiments (0.43–0.55). The use of an open-water jacket improves the performance of the heat exchanger by lowering the LMTD by 33.60% and lowering the heat transfer rate by 24.55%. Open-water life jackets do not significantly improve effectiveness.

This work proposes deployment of machine learning in the maintenance of individual constituent parts of steam power plant assemblages. With the condenser vacuum of a steam turbine (in a six-turbine plant assemblage) taken as a case study, information on the past operating parameters of the selected plant component was used to forecast its future working condition. Based on Exponential Gaussian Process of Regression, a model was developed, trained using the diachronic operational data, and employed in determining the future. A quantitative evaluation was employed to provide the distribution of the test values of the data about the lines of regression, as well as to measure the prediction accuracy of the model. The results show MAE and RMSE values are 6.1602 and 7.9286 respectively during the training; while for the prediction, the values are 92.6544 and 92.7235 respectively. It is concluded that modern power plants with myriads of instrumentation and data acquisition mechanisms can leverage on the approach of this study to model and plan the maintenance scheme that best suits and fits individual component units of power plants, since understanding of the anticipatory values of operational parameters helps to determine the likelihood of components failures. [ABSTRACT FROM AUTHOR]

This paper addresses a retrofitting vacuum membrane distillation (VMD) setup to reduce the accumulated pressure inside the permeated side. This modification is necessary to extend the operation of the VMD to extreme operation conditions of higher hot water temperatures. This modification, denoted as a hybrid configuration, proposes the injection of a cold water stream into the VMD cell without mixing it with the permeate. Energy and exergy efficiency analyses were performed to assess the effectiveness of the hybrid configuration. The performance of the modified system indicated an improvement in terms of permeate flux (J), the gain output ratio (GOR), and the utilitarian exergetic efficiency (ηex,u), which reach up to two and three times that of the base configuration of the VMD system. However, the exergetic efficiency (ηex) of the hybrid system showed marginal improvement compared to the base case over the tested range of hot water temperatures. This is because the enhanced vapor production is penalized by excess energy consumption. Moreover, the highest exergy destruction percentages occurred in the operational components (e.g., heater and chillers) which fall in the range of 19.0–68.9%. The exergy destruction percentage in the original components (e.g., the VMD cell and condenser) did not exceed 8.3%. Furthermore, this study indicated that the hybrid configuration requires additional tuning and optimization to perform efficiently over wide operating conditions.

This paper presents a profound solution for a novel method of dewatering dredged sludge using a combined geotextile tube and vacuum-assisted prefabricated horizontal drains. Firstly, an analytical model was proposed to provide a basis for the design of the proposed approach. This two-dimensional plane-strain consolidation model was based on Gibson's large-strain theory, incorporating the horizontal and vertical flows with consideration of the self-weight, nonlinear compressibility, and hydraulic conductivity of soil. Secondly, the numerical solution obtained using the alternative direction implicit method was compared with the existing one-dimensional model for verification. Thirdly, a field trial was carried out to evaluate the performance of the proposed approach and analytical model. Finally, the effects of various major design parameters on the consolidation efficiency of the tube system were also investigated through a parametric study to establish an optimal design. This study showed that a higher consolidation efficiency and an earlier optimal efficiency point could be achieved when decreasing the horizontal drain interval and increasing the tube height. Furthermore, surcharge preloading induces a more significant effective stress increment in soil than vacuum preloading of the same magnitude. [ABSTRACT FROM AUTHOR]

Air valves operate as protection devices in pipelines during drainage processes in order to mitigate vacuum pressures and control the transient flows. Currently, different authors have proposed one-dimensional models to predict the behaviour of orifices during filling and draining events, which offer good numerical results. However, the three-dimensional dynamic behaviour of air-admission orifices during drainage processes has not been studied in depth in the literature. In this research, the effects of air inflow on an orifice installed in a single pipe during drainage events are analysed using a three-dimensional computational fluid dynamics model by testing orifices with diameters of 1.5 and 3.0 mm. This model was validated with different experimental measurements associated to the vacuum pressure, obtaining good fits. The three-dimensional model predicts additional information associated to the aerodynamic effects that occur during the air-admission processes, which is studied. Subsonic flows are observed in different orifices with Mach numbers between 0.18 and 0.30. In addition, it is shown that the larger-diameter orifice ensures a more effective airflow control compared to the smaller-diameter orifice. [ABSTRACT FROM AUTHOR]

Objective: Aspiration thrombectomy is used to treat endovascular stroke treatment by clot removal through vacuum and suction forces. We aimed to investigate the pressures and suction forces generated by different pump systems for aspiration. Methods: Vacuum pressure was measured using a vacuum gauge with a closed tip for a 60cc syringe and aspiration pumps. Using an artificial thrombus made from polyvinyl alcohol hydrogel and latex membrane, we assessed the catheter tip force generated on an artificial thrombus using 5Fr Sofia and 6Fr Sofia PLUS intermediate catheters combined with Penumbra Jet Engine or Stryker Medela AXS Universal Aspiration Set. Subsequently, we calculated the catheter tip forces based on the pressure [catheter tip size (force = area x pressure)], and compared with the measured catheter tip force. Results: The 60cc syringe generated the highest vacuum pressure. Among the automatic pumps, the Penumbra jet engine generated the highest vacuum pressure. The catheter tip forces on the artificial thrombus and latex membrane were 18.5 ± 1.70 and 8.0 ± 1.23 gf, respectively, and 13.9 ± 1.37 and 5.6 ± 0.83 gf, respectively using the 5 Fr Sofia with the Penumbra Jet Engine and the Stryker Medela AXS Universal Aspiration Set, respectively. The corresponding values for the 6 Fr Sofia PLUS with the Penumbra Jet Engine and Stryker Medela AXS Universal Aspiration Set were 39.7 ± 3.88 and 20.7 ± 0.92 gf and 25.4 ± 4.96 and 18.0 ± 0.84 gf. For a constant catheter diameter and the automatic pump, the catheter tip force was significantly larger in the artificial thrombus than latex membrane (p < 0.001, ANOVA). Conclusion: The catheter diameter, vacuum pressure, and clot softness are positively correlated with the catheter tip force. [ABSTRACT FROM AUTHOR]

AerMet100 steel has strict composition and inclusion requirements. Therefore, its reaction with MgO refractory during vacuum induction melting cannot be ignored. In this study, the reaction mechanism between the MgO refractory and AerMet100 steel during the refining stage was investigated using a MgO crucible. The influence of the MgO crucible on AerMet100 steel composition and inclusions under refining vacuum pressures of 50–100 and 5–10 Pa was compared. The results indicate that SiO 2 , Al 2 O 3 , and MgO in the crucible decompose and are reduced by C in the liquid steel, which results in the increase of Si, dissolved Al (Als), and dissolved Mg (Mgs) content in the liquid steel. The increase of Ca content is due to the reduction of CaO in the crucible by C in the liquid steel. The reaction of Al 2 O 3 inclusions and Mgs in the liquid steel is the primary generation method of MgO·Al 2 O 3 spinel inclusions. As the Mgs content in the liquid steel increases, Al 2 O 3 inclusions transform into MgO·Al 2 O 3 spinel inclusions along the path Al 2 O 3 + Mgs → Al 2 O 3 with a small amount of MgO + Mgs → MgO·Al 2 O 3 spinel. In contrast, the vacuum pressure of 50–100 Pa is more effective at controlling the composition and inclusions of AerMet100 steel and is a more appropriate choice for the refining vacuum pressure. [ABSTRACT FROM AUTHOR]

The scientific task to improve energy efficiency and ensure the process of vacuum regime stabilization in the operation of milking machines has been solved. A mathematical model of the process of functioning of the servo control system of a rotary plate vacuum pump was built; the numerical modeling of its workflow was carried out. This paper reports the results of experimental studies on the influence of the regime parameters of the rotary plate vacuum pump on the efficiency of its operation, as well as the results of experimental research on the servo control system for the rotary plate vacuum pump. The operational process of the rotary plate vacuum pump HB-1200 for a milking machine was investigated. The influence of mode parameters (rotor speed n and vacuum pressure P) on the performance of the vacuum pump, Qa, vacuum pressure fluctuation, ΔP, and the power consumption of the vacuum pump drive, Np, has been determined. The servo control system of the rotary plate vacuum pump was experimentally investigated based on the developed algorithms of its operation. In a generally accepted algorithm, vacuum fluctuation increases with increasing an airflow rate: at ΔQa = 45 l/min – ΔP = 2.3 kPa; at ΔQa = 90 l/min – ΔP = 4.6 kPa; at ΔQa = 135 l/min – ΔP = 6.4 kPa. Unlike the generally accepted one, the developed algorithm enables a stable vacuum mode with the largest vacuum fluctuation being ΔP = 2.4 kPa. For the first time, the functional dependence of the influence of the regime parameters of the rotary plate vacuum pump with its automatic servo control system on the stability of the vacuum regime of a milk-vacuum system in the milking machine was established. The results can be applied when improving milking machines in terms of ensuring the stabilization process of the vacuum regime. [ABSTRACT FROM AUTHOR]

Purpose: To determine the actual vacuum pressure generated by the Oertli CataRhex 3® (Oertli), using an external measuring system. Methods: The effective vacuum pressure created by the Oertli was measured with a pressure device that was continuous with the vacuum tubing system while closed to the external environment. Measurements were taken with the machine set to 300 and 500 mmHg at flow rates of 20, 35, and 50 mL/min and at bottle heights of 60, 80, and 100 cm. Pressures were recorded after the foot pedal was depressed to vacuum setting (second position), and the pressure was allowed to stabilize. Subsequently, it was compared to the pressure value displayed by the machine. Results: Externally measured vacuum pressure was on average 13.02% greater (39.05 mmHg) than displayed vacuum pressure at 300 mmHg (P < 0.005) and 8.60% greater (42.98 mmHg) than displayed vacuum at 500 mmHg (P < 0.005). The average difference between displayed and measured pressure increased with increasing bottle heights. Conclusion: On average, the vacuum pressure generated in the Oertli was found to be significantly higher than the machine's reading when the machine was set at 300 mmHg and 500 mmHg. Adjusting vacuum had variable effects on the measured versus displayed pressure readings. [ABSTRACT FROM AUTHOR]

To improve the problem of low seeding efficiency facing the single-row planting mode traditionally used in China, this study aimed to design a novel three-row pneumatic precision metering device. The working principle and main structure were introduced in the paper. The three main factors affecting the seeding performance comprised of vacuum pressure, angular velocity of the metering tray, and taper angle of the sucking hole. A Box-Behnken experiment design having the qualified index and missed seeding index as the experimental index was used, and the results indicated that optimal performance of the metering device was achieved when the vacuum pressure was 2.16 kPa, the angular velocity of the metering tray was 29.43 rpm, and the taper angle of the sucking hole was 61.51°. The qualified index of the inner, middle, and outer ring was 95.12%, 94.68% and 94.24% respectively, while the missed seeding index of the inner, middle, and outer ring was 3.67%, 3.12% and 2.58% respectively under the optimal combination of parameters. The bench test results were basically consistent with the optimized results. This paper can provide support for the design of a three-row pneumatic precision metering device for Brassica chinensis. [ABSTRACT FROM AUTHOR]

Conventional landslide drainage methods always seem to lack a long-term and efficient drainage capacity. Thus, it is necessary to develop a new drainage method that does not have these disadvantages. In this study, a new, self-starting drainage method is proposed based on the results of tests that were conducted with a physical model. The principle involved is that the drainage starts automatically when the level of the groundwater above the front end of the permeable pipes is higher than the orifice. A vacuum is generated in the permeable pipe after the flow begins in the pipe, and it is transmitted forward in the surrounding soil. Then, an unsaturated zone can be created in the soil during the transmission process, so the stability of the slope is expected to be improved. The results of the model test indicated that the diameter of the hose is an important factor that affects the drainage. Compared with siphon drainage, this method solves two problems simultaneously, i.e. it avoids the accumulation of air that could interfere with the siphon effect and it avoids the manual start-up. [ABSTRACT FROM AUTHOR]

• Vacuum pressure in the HL-3 vacuum vessel reached to 1.8 × 10-6 pa. • The temperature of the VV is baked by nitrogen to 176 °C. • A solution based on control variable method is used to adjust the temperature difference between the divertor and the VV. • A 100 % zero oil-free, high speed centrifugal fan is developed for the HL-3 baking system. HL-3 is a tokamak device constructed in 2020 and it has achieved remarkable results in a short period of time. Baking is an important way to obtain a high vacuum required for plasma discharge in tokamak devices. A nitrogen gas closed-circuit reheat baking system is utilized to concurrently bake the vacuum vessel (VV) and the lower divertor of HL-3. So far, three rounds of baking experiments have been carried out, with vacuum pressure up to 1.8 × 10–6 Pa and the results from the mass spectrometer indicated that the amount of compounds were greatly reduced in the residual gas. Besides the design description and experimental results of HL-3 baking system, this paper also introduces a simulation-based solution for addressing the issue of the lower divertor temperature being significantly lower than that of the VV after baking to the high temperature stage. [ABSTRACT FROM AUTHOR]

Portable ion trap mass spectrometers, especially for those with continuous atmospheric pressure interfaces, usually implement vacuum pumps with limited power for miniaturization, which leads to high vacuum pressures and reduced resolutions. In this study, two three-stage high-resolution ion isolation methods of SWIFT - AC frequency sweep - SWIFT and SWIFT - RF voltage ramp - SWIFT were proposed. Compared to the 2.8 m/z isolation resolution of the traditional SWIFT ion isolation method, higher isolation resolutions of 2.2 m/z and 1.5 m/z have been achieved by SWIFT - AC frequency sweep - SWIFT and SWIFT - RF voltage ramp - SWIFT ion isolation methods at an isolation efficiency of 40 %. In addition, our detailed experiments showed that all ion isolation methods can obtain higher isolation resolution under the conditions of lower vacuum pressure, higher isolation q value, and stronger axial confinement potential barrier, like which the mass resolution behaves. In order to inspect the effectiveness of the high-resolution isolation method, the control experiments of hair samples spiked with drugs had been conducted. The signal-to-noise ratio of O6-monoacetylmorphine can be improved by a factor of 2.4 using the SWIFT - RF voltage ramp - SWIFT ion isolation method. Our research results indicate that the performance of ion trap tandem mass spectrometry can be effectively improved by using the three-stage high-resolution ion isolation methods. [Display omitted] • High isolation resolution can be obtained under a low vacuum pressure, high q value, and strong axial potential barrier. • Three-stage ion isolation method can improve the isolation resolution from 2.8 m/z to 1.5 m/z. • Fragment ions can be eliminated by the last rough isolation stage. • Detection sensitivity of portable ITMS can be improved by a factor of 2.4 using the new isolation method. [ABSTRACT FROM AUTHOR]

This article demonstrates the results of experimental research one of the pulsators. Its main difference from others is a pneumatic electromagnetic pulsator in combination with a collector. Therefore, this article describes in detail the process of studying the pulsator. The planned experiment was carried out on by Factorial experiments with multiple factors. The influence of factors (the ripple frequency n, the milk ejection q and the ratio between strokes t/T) on the vacuum pressure in the inter wall chamber of teat cups was studied. The regression equation of the dependence response criterion on factors is modeled. This dependence is demonstrated graphically. Also there is a contour graph which is for more detailed information. [ABSTRACT FROM AUTHOR]

In this study, a new design of photovoltaic thermal (PV/T) collector is proposed. This design uses a vacuum layer above the silicon wafer and not exists in the traditional PV/T collector. This layer is used to decrease the heat loss from the top surface of the PV/T collector. The analysis is conducted using a 3D thermal modeling. The new collector design with the vacuum layer achieved a 26.6% increase in the thermal power while keeping the electrical the same at Reynolds number of 50 and solar radiation of 1000 W/m2. In addition, the degradation of the vacuum pressure slightly influence the thermal performance while increasing the vacuum pressure from 0.01 Pa to 10 Pa. While further increase in the vacuum pressure from 10 Pa to 1.013×105 Pa substantially decreases the gained thermal power with insignificant increase in the electrical power.

This article demonstrates the results of experimental research one of the pulsators. Its main difference from others is a pneumatic electromagnetic pulsator in combination with a collector. Therefore, this article describes in detail the process of studying the pulsator. The planned experiment was carried out on by Factorial experiments with multiple factors. The influence of factors (the ripple frequency n, the milk ejection q and the ratio between strokes t/T) on the vacuum pressure in the inter wall chamber of teat cups was studied. The regression equation of the dependence response criterion on factors is modeled. This dependence is demonstrated graphically. Also there is a contour graph which is for more detailed information. Article in English. Pneumatinio elektromagnetinio pulsatoriaus su kolektoriumi tyrimo rezultatai Santrauka Šiame straipsnyje yra pateikti vieno iš pulsatoriaus eksperimentinio tyrimo rezultatai. Esminis išskirtinis šio pulsatoriaus bruožas – kolektoriaus buvimas. Buvo atliktas išsamus faktorinis eksperimentas. Tiriamas tokių faktorių, kaip pulsacijų dažnio n, pieno išskyrimo q ir taktų santykio t/T, poveikis vakuuminiam spaudimui vidinėje melžimo mašinos kameros sienelėje. Buvo suformuluota regresinė lygtis, vaizduojanti faktorių priklausomybės atsako kriterijų. Ši priklausomybė pavaizduota grafiškai. Taip pat yra pridėtas kontūrinis grafikas detalesnei informacijai pademonstruoti. Reikšminiai žodžiai: melžimo mašina, pulsatorius, elektromagnetinis pulsatorius, kolektorius, vakuuminis spaudimas, pulsacijos dažnis, išmesta pieno masė, faktoriai.

This paper presents a case study on the improvement of thick marine deposits. A new method that combines vacuum pressure and surcharge load with no need for a sand cushion is proposed and evaluated. The main features of this method are as follows: (1) each integrated prefabricated vertical drain (PVD) is connected directly to a branch pipe, which is in turn connected to a main pipe with a T-shaped connector, and (2) a less expensive hill-skill soil layer is used to replace the sand cushion. After improving the soil by using this method, the total ground settlement, the lateral deformation and the undrained shear strength were all greater for a 20-m PVD than for a 15-m PVD. The average degrees of consolidation achieved were both greater than 80%. This method could provide design criteria for reclaimed land in other projects. [ABSTRACT FROM AUTHOR]

Well resistance depends on discharge capacity of prefabricated vertical drains (PVDs), which affects the consolidation rate of soil at high water content importantly. Due to the lack of an axisymmetric large-strain consolidation model considering well resistance under vacuum pressure, the effect of well resistance on the degree of consolidation of ultra-soft soil is not clear. An axisymmetric large-strain consolidation model under vacuum pressure accounts for well resistance, self-weight stress, and vacuum attenuation along depth; both vertical and radial flow are proposed. Existing models established by Cao et al. and Nguyen et al. are special cases of the proposed model. The model and calculation method in this study are verified by the reported laboratory tests. The change laws of degree of consolidation defined by stress affected by key parameters of well resistance factor are discussed. It is found that the development of degree of consolidation will be delayed by the decreases of discharge capacity of PVDs and initial water content, as well as the increases of spacing ratio and time parameter of well resistance. The minimum demands of discharge capacity of PVDs with negligible well resistance increase exponentially with the increase of length of PVDs. The attenuation of vacuum pressure along the depth has greater influence on the degree of consolidation of soil than the attenuation of discharge capacity along the depth. [ABSTRACT FROM AUTHOR]

This study examined the effects of seed drop height changing depending on furrow openers of precision seeders, and the forward speed of tractors which is constantly aimed to be increased by producers on the uniformity of seed distribution. The experiments were made with a precision seeder unit positioned on a sticky belt trial setup at seed drop heights of 100, 200 and 300 mm, the forward speeds of 0.5, 1.0, and 1.5 m s-1, and the vacuum pressures of 6.0, 7.5, and 9.0 kPa. Maize and sunflower seeds were used in experiments. According to the results, the effects of seed drop height and forward speed on seed spacing and deviation from row were significant for both seed types (P<0.01). The increase in the forward speed led to a deviation of approximately 15 mm in maize and 17 mm in sunflower between the mean seed spacing and the target seed spacing. In general, miss and multiple indices were found to be fewer than 9%. The optimum performance of the seeder unit in sowing sunflower and maize was obtained at the seed drop height of 100 mm, the forward speed of 0.5 m s-1, and the vacuum pressure of 9.0 kPa. Consequently, it is suggested that, in contrast to what is demanded, the forward speed cannot be increased as much as one desires, and the dimensions of furrow openers that changed depending on the seed drop height should be designed under certain standards. [ABSTRACT FROM AUTHOR]

The pumping performance of the traditional vertical well is often poor in municipal solid waste (MSW) landfills due to the blocking effect of landfill gas on leachate migration. To improve the pumping performance, a vacuum vertical well was designed and then installed at the Tianziling landfill. When the leachate was drawn out through submersible pump, the landfill gas was simultaneously extracted through vacuum pump to form vacuum pressure in the well. The vacuum pressure could increase the hydraulic gradient of leachate flow as well as the relative liquid permeability of MSW. Pumping tests were carried out to explore the effectiveness of the vacuum pressure on improving the pumping performance of vertical well. When the vacuum pressure increased from 0 kPa to − 30 kPa, the steady leachate pumping rate increased from 1.58 to 2.34 m3/h, and the steady leachate level drawdown increased from 5.9 to 10.3 m at the distance of 5 m. The vacuum pressure mainly affected the leachate level drawdown within the distance of 15–20 m. When the vacuum pressure in the pumping well was − 30 kPa, it attenuated to − 14.7 kPa and − 6.6 kPa at the distance of 5 m and 10 m, respectively. The influence radius of vacuum pressure was about 15 m. Numerical modeling indicates that the leachate pumping rate and drawdown will decrease with the increase in decreasing rate of hydraulic conductivity with depth, degree of heterogeneity, and anisotropy of hydraulic conductivity of waste. The experimental and numerical results demonstrate the effectiveness of vacuum pressure and provide working parameters for the application of the vacuum wells in MSW landfills. [ABSTRACT FROM AUTHOR]

The Resin transfer molding (RTM) process is a closed mold process to produce composite products in mass production. This method includes various parameters such as mold temperature, vacuum pressure, injection point, fiber volume fraction, injection pressure and so on. Parts with the desired surface quality and high properties can be achieved by controlling these parameters. In this study, the effect of input parameters of resin transfer molding process including vacuum pressure, injection point and mold temperature on mold filling time, curing time, tensile strength and flexural strength of carbon-epoxy composite was investigated. Each of the input parameter has been investigated at three levels using the RSM full factorial method. Finally, after making carbon/epoxy composite samples with this process, their evaluation in terms of filling time, curing time and mechanical properties have been investigated. The results showed that the injection point has a significant effect on the mechanical properties and production volume of the part in the Resin transfer molding process. According to the results, the optimal sample was determined by prioritization mechanical properties with mold temperature parameters of 106.7° C, vacuum pressure of 0.83 bar and injection point B (one resin input in the middle of the part and two vacuum outputs at the end of the part). Tensile strength of the sample was 546.7 MPa, flexural strength was 759.2 MPa, curing time was 7.3 minutes and mold filling time was 8.6 minutes by software. [ABSTRACT FROM AUTHOR]

To improve the problem of low seeding efficiency facing the single-row planting mode traditionally used in China, this study aimed to design a novel three-row pneumatic precision metering device. The working principle and main structure were introduced in the paper. The three main factors affecting the seeding performance comprised of vacuum pressure, angular velocity of the metering tray, and taper angle of the sucking hole. A Box-Behnken experiment design having the qualified index and missed seeding index as the experimental index was used, and the results indicated that optimal performance of the metering device was achieved when the vacuum pressure was 2.16 kPa, the angular velocity of the metering tray was 29.43 rpm, and the taper angle of the sucking hole was 61.51°. The qualified index of the inner, middle, and outer ring was 95.12%, 94.68% and 94.24% respectively, while the missed seeding index of the inner, middle, and outer ring was 3.67%, 3.12% and 2.58% respectively under the optimal combination of parameters. The bench test results were basically consistent with the optimized results. This paper can provide support for the design of a three-row pneumatic precision metering device for Brassica chinensis.

This paper addresses a retrofitting vacuum membrane distillation (VMD) setup to reduce the accumulated pressure inside the permeated side. This modification is necessary to extend the operation of the VMD to extreme operation conditions of higher hot water temperatures. This modification, denoted as a hybrid configuration, proposes the injection of a cold water stream into the VMD cell without mixing it with the permeate. Energy and exergy efficiency analyses were performed to assess the effectiveness of the hybrid configuration. The performance of the modified system indicated an improvement in terms of permeate flux (J), the gain output ratio (GOR), and the utilitarian exergetic efficiency (η ex,u ), which reach up to two and three times that of the base configuration of the VMD system. However, the exergetic efficiency (η ex ) of the hybrid system showed marginal improvement compared to the base case over the tested range of hot water temperatures. This is because the enhanced vapor production is penalized by excess energy consumption. Moreover, the highest exergy destruction percentages occurred in the operational components (e.g., heater and chillers) which fall in the range of 19.0-68.9%. The exergy destruction percentage in the original components (e.g., the VMD cell and condenser) did not exceed 8.3%. Furthermore, this study indicated that the hybrid configuration requires additional tuning and optimization to perform efficiently over wide operating conditions.

The study assessed the effect of jatropha, linseed, eucalyptus, neem and jojoba oils on protection of three wood species (Acacia nilotica, Dalbergia sissoo and Pinus wallichiana) against termite attack by Odontotermes obesus. Conditioned and pre-weighed blocks of each wood species were vacuum-pressure impregnated with a 15% concentration of the oil-ethanol solutions.. Resistance of treated and untreated wood against termites was tested under laboratory as well as field conditions using choice and no-choice tests. Oil treated wood showed significant reductions in weight loss compared to control treatments. Complete termite mortality was recorded for all oil treatments except eucalyptus oil. Linseed oil showed good results in each treatment in terms of feeding resistance as well as mortality of termites followed by neem, jatropha, jojoba and eucalyptus oil. The lower weight losses were found in both choice and no-choice field tests for linseed oil treated Dalbergia sissoo while untreated Pinus wallichiana sapwood had the greater weight loss. It was observed that the oil retention was significantly more in sapwood than in heartwoods. The retention of oils justified that wood with high oil retention showed more resistance against the termite except eucalyptus oil treatment of Pinus wallichiana.

In this study, a novel osmotic membrane was developed by polyamide (PA) coating on the tubular electrospun nanofiber (TuEN) support membrane. Water and reverse salt flux properties of the obtained membrane were investigated by applying pressure in addition to the osmotic forces. Surface characterization of the membrane was carried out by Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) analyses and flux performance tests were performed in both cross flow and submerged membrane setups. Applying pressure from the feed to the concentrate side had significant effects on the water and salt fluxes. Higher pressure differences between the feed and concentrate sides resulted in unexpected high water fluxes up to 500 Lm−2h−1 (LMH). Besides, the pressure helps to transfer the salt content of feed water into the concentrate side, differently from the osmotic process preventing the salinity build-up at the feed side. PA coated TuEN membrane operated under pressure will exhibit a favorable solution in water/wastewater treatment applications, especially for membrane bioreactors (MBR) in terms of preventing salt accumulation in the bioreactor, decreasing the membrane fouling, increasing the volume of product water, and enabling the concentrate management. [ABSTRACT FROM AUTHOR]

Specific gas permeability of beech wood was determined and compared with values obtained after nanosilver-impregnation and heat-treatment in three mediums of air, water, and water steam at 150 °C for four durations of 1, 2, 3, and 4 h. Separate sets of specimens for each group were prepared and impregnated with a 400 ppm aqueous nanosilver suspension. The results revealed that the effect of heat treatment in hot-air depended on the duration of treatment. Hydrothermal treatment generally increased gas permeability, this was attributed to the dissolving of extractives in the hot water medium, although lower duration of one hour did not significantly change permeability. Hygrothermal treatment increased gas permeability at all four durations, revealing its effectiveness as a pre-treatment to improve penetration of preservatives and fire-retardants into wood texture in wood preservation industry. High thermal conductivity of silver nanoparticles intensified the effects of heat treatment in all mediums. [ABSTRACT FROM AUTHOR]

The study assessed the effect of jatropha, linseed, eucalyptus, neem and jojoba oils on protection of three wood species (Acacia nilotica, Dalbergia sissoo and Pinus wallichiana) against termite attack by Odontotermes obesus. Conditioned and pre-weighed blocks of each wood species were vacuum-pressure impregnated with a 15% concentration of the oil-ethanol solutions. Resistance of treated and untreated wood against termites was tested under laboratory as well as field conditions using choice and no-choice tests. Oil treated wood showed significant reductions in weight loss compared to control treatments. Complete termite mortality was recorded for all oil treatments except eucalyptus oil. Linseed oil showed good results in each treatment in terms of feeding resistance as well as mortality of termites followed by neem, jatropha, jojoba and eucalyptus oil. The lower weight losses were found in both choice and no-choice field tests for linseed oil treated Dalbergia sissoo while untreated Pinus wallichiana sapwood had the greater weight loss. It was observed that the oil retention was significantly more in sapwood than in heartwoods. The retention of oils justified that wood with high oil retention showed more resistance against the termite except eucalyptus oil treatment of Pinus wallichiana. [ABSTRACT FROM AUTHOR]

Keywords: Highly stressed soft rock; 3D printing; Vacuum pressure; Mechanical and fracture properties In addition, to further illustrate the feasibility of the proposed method in reproducing the mechanical behavior of highly stressed soft rock, the stress-strain behavior and failure modes of the 3D-printed samples are compared with those of a natural soft rock in detail. Furthermore, the overall mechanical behaviors of real highly stressed soft rock are very sensitive to the constituent particle interface properties and the geological conditions, which have to be considered for warranting a more realistic replication of real highly stressed soft rocks. [Extracted from the article]

Experiments were carried out to optimize the parameters of cell tray vegetable seeder with the aim of adopting it to a specific working conditions. Two major factors, the vacuum pressure in the seeding drum and suck hole diameter were tested on cabbage seeds (Valentina cultivar) and plastic tray with 64 cells at three levels (–1, 0, +1) for each factor using the orthogonal central composite design (CCD) regression experiment. The effects of these factors on the single-seed rate (seed singulation), double-seed rate and empty-seed rate were investigated. The experimental results showed that major factor affecting single-seed rate, empty-seed rate and multi-seed rate was vacuum pressure, while suction hole diameter do not affect double-seed rate. It has been established that the round holes of the seeding drum conform to the round-shaped cabbage seeds to ensure high-quality seeding within the required agrotechnical indices — up to 96.0 % of single-seed sowing, and up to 4 % seeding of cells with double and emptyseed rate. The study determined the optimal parameters of vacuum pressure to be 2,9 kPa and 1,0 mm for suction hole diameter at a constant speed of conveyor belt 2,4 m/min. These parameters provided the basis for design and performance improvement of the tray vegetable seeding mechanism.

Clogging will inevitably occur while using vacuum preloading method to process super-soft soils with high water content. How to quantitatively evaluate the effect of clogging on the consolidation behavior is a key issue to be solved. Based on NALSC (negative axisymmetric large-strain consolidation) model, considering the "internal clogging" and the "external clogging", a calculation method by using parameter "clogging rate" to reflect clogging problem is proposed for single-well consolidation theory. Effects of clogging rate and clogging occurred time on Us (degree of consolidation defined by strain) and Up (degree of consolidation defined by stress) are investigated. Differences of the effect of clogging on consolidation degree are determined between large-strain and small-strain consolidation theory. The results show that, the larger the clogging rate, the smaller the degree of consolidation of the soil at the same consolidation time. Effect of clogging on Up is greater than Us. The earlier the clogging occurs, the smaller the degree of consolidation at the same clogging rate. Influences on the degree of consolidation for large-strain and small-strain theory are the same. Consolidation rate of soil is determined to a certain extent by the "generalized clogging parameter μ". The "external clogging" has a greater influence on the degree of consolidation than the "internal clogging" at the same clogging rate. [ABSTRACT FROM AUTHOR]

Although direct contact aspiration has emerged as one of the leading techniques for mechanical thrombectomy (MT), there is still ongoing debate about the aspiration/suction pump devices that can optimize recanalization rates. To address this gap, we conducted a meta-analysis comparing the aspiration efficacy of 60 ml syringe and pump devices in benchtop MT models.Systematic literature review was conducted using Medline, Embase, Web of Science, and Scopus in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. Outcomes of interest included flow rate and vacuum pressure delivered by a 60 ml syringe and several aspiration pumps. We used a random effects model to calculate the mean difference (MD) with 95% confidence intervals (CIs) and a statistically significant difference was considered as a two-sided p-value of less than 0.05.We included six benchtop studies comparing 60 ml syringes and vacuum pumps. Our meta-analysis showed that there were no significant differences in vacuum pressure (MD:0.71inHg, 95% CI: [−0.81;2.23], p = 0.359) and flow rate (MD:0.27 mL/s, 95% CI: [−3,07; 3.61], p = 0.873) between 60 ml syringes and vacuum pumps groups.Our study demonstrated comparable performance in terms of vacuum pressure and flow rates between a 60 ml syringe and a heterogeneous combination of commercially available aspiration pumps. [ABSTRACT FROM AUTHOR]