As a new type of hydraulic system, the independent valve control system (IMCS) has higher flexibility compared with the traditional four-side slide valve control system. The independent metering control system (IMCS) is divided into four quadrant modes, based on the speed and load of the actuator. The traditional control methods always use a discrete control strategy to realize the switching between different modes based on mode recognition. However, the spool signals frequently switch, and the actuator operating pressure and speed are not stable when the IMCS is switched between different modes. To solve the above problems, this paper proposes a continuous control strategy for the IMCS. Based on the fuzzy control principle, the variable universe fuzzy controller (VUFC) was designed. The controller contains 49 fuzzy rules, and the output of the controller at any time is calculated by the weighted sum of several fuzzy rules. The VUFC divides the system into 49 rules, which are activated... [more]

The challenges posed by elevated rock hardness, deficient drillability, excessive friction torque, and significant underpressure in extended−reach horizontal wells are the primary factors that contribute to low ROP (Rate of Penetration) and limited horizontal reach during the drilling operation. Reducing drag and friction is one of the primary methods of addressing the aforementioned challenges. To augment the pulse output characteristics of the oscillating jet and bolster the energy of the hydrodynamic impact load, we developed and designed a multi−source impact oscillation speed−increasing tool coupled with blade rotation disturbance and multi−order oscillation cavity self−excitation. We utilized fluid dynamics software to model and conduct numerical analysis on the multi−source pulsed jet generator. Furthermore, we constructed a prototype and subjected it to testing. This paper examines the impact of dimensionless structural parameters on the pressure output characteristics of the m... [more]

The 1000 MW hydro-generator unit has huge geometrical dimensions and requires high installation accuracy. The control of its installation deviation will directly affect the installation quality and operational performance of the unit and the rotor eccentricity is one of the core problems faced in the installation and operation of the giant hydro-generator unit. This paper presents a method to calculate the asymmetric magnetic field by means of the transient finite element calculation to reveal the effect of the generator rotor radial deviation on the unbalanced magnetic pull of the unit. The effects of rotor dynamic eccentricity on the magnetic field are analyzed in the time and frequency domains, respectively. The results show that both the DC component and the key harmonic component of the unbalanced magnetic pull increase with the increase of the eccentricity value, and this variation relationship is nearly linear. when the eccentricity is no more than 0.15 mm, the unbalanced magnet... [more]

Wheat straw is a suitable source material for bioethanol production. Removing lignin and hemicellulose in wheat straw to improve enzymatic hydrolysis efficiency is essential because of its complex structure. Deep eutectic solvents (DESs) have become substitutes for ionic liquids (ILs), with the characteristics of good biocompatibility, simple synthesis procedure and low cost. However, the process of removing lignin and hemicellulose using present DESs requires a high operation temperature or long operation time. Therefore, we studied a novel method under mild conditions for screening a series of novel DESs based on an inorganic base to remove lignin and hemicellulose in wheat straw. In this work, the effect of DES type, the pH of the DESs, the operation temperature and operation time for enhancing enzymatic hydrolysis, and the crystal structure and the chemical structure and surface morphology of wheat straw were investigated. In particular, Na:EG exhibited the most excellent solubilit... [more]

This work aimed to establish an integrated approach to investigate the total phenolic content and antioxidant activities of dried skim camel and cow milk and their fractions. The milk fractions were obtained by acid or enzymatic coagulation followed by spray drying (inlet temperature/outlet temperature: 125 ± 2 °C/90 ± 2 °C) or freeze drying (−50 °C, 0.05 mbar) coupled or not to gamma irradiation (at 5, 11, 22 kGy). The results showed that the total phenolic content (measured in gallic acid equivalent, GAE) varied depending on the drying technique. The freeze-drying process corresponded to the highest values of total phenolic compounds, with 247.23 ± 2.08 mg GAE/100 g powder for the β-casein fraction of camel milk (βC CaM) and 621.13 ± 4.16 mg GAE/100 g powder for the β-casein fraction of cow milk (βC CoM). Compared to spray-dried fractions, freeze-dried fractions showed generally higher ferric reducing antioxidant power for both camel milk and cow milk. The highest values of free radi... [more]

This paper studies the effect of gravity orientation on a heat sink, used to passively cool a thick film resistor, by changing the assembly orientation. Using the same geometry and boundary conditions as in the experimental setup, finite element simulations were conducted to evaluate the accuracy of Siemens Flotherm XT 2021.2 simulation software. In order to determine the influence of heat sink orientation, experimental measurements were performed on the resistor and heat sink temperature using thermocouples. Siemens Simcenter Flotherm XT 2021.2 software (Siemens, Munich, Germany) was used to perform finite element simulation. The influence of the heat sink position was evaluated on two setups, one where the resistor is placed directly on the heat sink using screws, and the second one, where a thermal pad was placed between the resistor and the heat sink. Screws were to clamp the parts in both cases. In total, four experiments and simulations were performed with two assemblies with two... [more]

At present, PE pipelines are widely used in urban gas pipeline networks. As pipeline safety is of great importance to the gas supply, this paper focuses on the safety and reliability of PE pipes during service. First of all, this paper analyzes the aging factors of PE materials and the failure forms and mechanisms of PE pipes. Second, the performance testing methods of PE pipelines are summarized, including pipeline pressure tests, pipeline condition inspections, welded joint inspections, mechanical performance tests, and physical performance tests. In addition, life prediction methods for PE pipelines are introduced and analyzed. The methods and applicability of tensile experiments and DSC experiments based on thermal oxygen aging are both analyzed, and the corresponding experiments are also carried out. On the basis of the above research, the technical system of the integrity detection and evaluation of urban gas pipelines is finally established. The system includes the integrity det... [more]

In traditional kerogen pyrolysis experiments, the effects of minerals and rock fabric on the pyrolysis products were ignored. To further clarify the role of the mineral matrix and rock fabric on hydrocarbon generation and retention, a closed anhydrous pyrolysis experiment was conducted on core plugs, powdered rock and kerogen from a clay-rich sample of Maoming oil shale within a temperature range of 312 °C to 600 °C, at a fixed pressure of 30 Mpa. The experiment’s results showed that the yields of heavy hydrocarbons (C14+) generated from the core plugs and powdered rock were obviously lower than that of kerogen, which may be caused by the retention effect of clay minerals in raw shale. The yields of gaseous hydrocarbons generated from core plugs were lower compared with powdered rock due to the retention of C2+ hydrocarbons by the intact rock fabric and the preferential generation of methane. Light hydrocarbon (C6-14) yields generated from the core plugs and powdered rock were higher t... [more]

Over past decades, the green method of synthesizing metal nanoparticles has acquired more attentiveness by scientific consensus because of its industrial and biomedical applications. This study focuses on the anti-proliferative effectiveness of AgNPs synthesized from Rotheca serrata (L.) Steane & Mabb. flower bud extract against the PANC-1 cell line in vitro. Various analytical instruments were utilized to visualize the formation of RsFb-AgNPs, such as UV-Vis spectroscopy, FT-IR, SEM, EDS, TEM, XRD, Zeta potential, and DLS analysis. The biosynthesis of RsFb-AgNPs was observed by a change in color and UV-Vis spectroscopy (415 nm). The FT-IR spectra exhibited the existence of many functional groups. XRD confirmed the crystallinity of the AgNPs. Morphology and elemental mapping were assessed by SEM and EDS analysis. The TEM micrograph revealed spherical-shaped particles with sizes ranging from 12 to 40 nm. Zeta potential and DLS analysis were used to measure surface charge and particle si... [more]

The control difficulty of whole coal cavern groups is greatly increased due to the characteristics of soft rock with low strength, large sections, and the mutual influence of crossed cavern groups. The large section gas storage cavern group is taken as the research background. In this paper, the equivalent circle method is used to solve the loose circle of a rectangular roadway, and numerical calculation is used to obtain the deformation and stress distribution laws of the surrounding rock under the excavation conditions of large section whole coal cavern groups (WCCG). The deformation and failure mechanisms of the surrounding rock are revealed under the linkage impact between large section whole coal cavern groups. The stratified reinforcement ring concept of “long cable-bolt-grouting” (LBG) was proposed for the stability control of surrounding rock in the WCCG. On the roof of whole coal cavern groups, the supporting configuration of a high-strength bolt with a high pre-tightening for... [more]

For decades, the benefits of utilizing hollow fiber bioreactors for continuous cell culture to produce monoclonal antibodies have been widely recognized. However, the suitability of this technology for laboratories or centers with limited resources and expertise seeking to expand their production capacity is uncertain, mainly due to unknown cost-effectiveness. In this study, a hollow fiber bioreactor with a 4.7-mL culture volume was used to culture a hybridoma clone producing immunoglobulin G antibody specific to hemoglobin F (HbF). The antibody reached a maximum concentration of 1.22 g/L and totaled 21 mg over a 44-day culture period. This preliminary production data was used to estimate the cost of consumables required for using the hollow fiber bioreactor to produce 130 mg of monoclonal antibodies, which was found to be THB35.8k (£880). The cost was slightly more expensive than batch cultivation in typical culture dishes, which ranged from THB27.8 to 30.2k (£680 to 740). Despite the... [more]

In this work, a numerical simulation study on the mixing characteristics of multiphase flow in an autoclave was carried out using CFD technology. The Eulerian−Eulerian model and discrete phase model (DPM) were employed to investigate the solid holdup, critical suspension speed, nonuniformity of solid suspension, gas holdup distribution, bubble tracks, and residence time during stirring leaching in the autoclave. Experiments validate the accuracy of the numerical model, and the experimental values correspond well with the simulation results. The numerical simulation results show that the solid−liquid mixing is mainly affected by the axial flow, the best agitation speed is 400 rpm, and increasing the speed further cannot make the mixture more homogenous and buildup occurred above the autoclave. The calculated critical suspension speed is 406 rpm, which is slightly lower than that obtained from the empirical formula. The gas phase is mainly concentrated in the vortex area above the blade.... [more]

Blends combine advantageous characteristics of each species, resulting in products with different flavors and nutritional substances. Moreover, transforming them into powder provides numerous advantages. This work evaluated the properties of three blended foam formulations made from the pulps of tropical red fruits (acerola, guava and pitanga) to determine the foam layer drying kinetics and thermodynamic properties. The foam formulations were prepared by mixing the three pulps in equal proportions (1:1:1), all added with 6% albumin and 1% stabilizing agent. The foams were analyzed for density, volumetric expansion, stability and porosity in six mixing times. Subsequently, they were subjected to drying in an oven with forced air circulation at 4 temperatures, with a layer 0.5 cm thick. Seven mathematical models were fitted to the drying kinetics experimental data to determine the effective diffusivity and thermodynamic properties of the samples. The best mixing times were 5 min for the... [more]

Vehicle mass is crucial to autonomous vehicles control. Affected by the nonlinearity of vehicle dynamics between vehicle states, it is still a tough issue to estimate vehicle mass precisely and stably. The transformer aided adaptive extended Kalman filter is proposed to further improve the accuracy and stability of estimation. Firstly, the transformer-based estimator is introduced to provide an accurate pre-estimation of vehicle mass, with the nonlinear dynamics among vehicle states being learned. Secondly, on the basis of comparing the real-time input and training data of neural network, the weight adjustment module is designed to present an adaptive law. Finally, the adaptive extended Kalman filter is proposed to meet the demand of accuracy and stability, where the pre-estimation of transformer-based estimator is integrated with the adaptive law. Dataset is collected by conducting heavy-duty vehicle simulation. The mean absolute percentage error, mean absolute error, root mean square... [more]

Removable pressure-sensitive adhesives (PSAs) are used in the production of self-adhesive materials such as protective films, masking tapes or biomedical electrodes. This work presents a new and environmentally friendly method of obtaining this type of adhesive materials, i.e., photochemically induced free radical telomerization. Adhesive binders to removable PSAs, i.e., the photoreactive acrylic telomer syrups (ATS) were prepared from n-butyl acrylate, acrylic acid, and 4-acrylooxybenzophenone. Tetrabromomethane (CBr4) or bromotrichloromethane (CBrCl3) were used as the telogens. ATS was modified with unsaturated polybutadiene resin and a radical photoinitiator. Adhesive compositions were coated onto a carrier and UV cross-linked. The effects of the chemical nature of telomers (i.e., terminal Br or Cl atoms) and their molecular weight (K-value), as well as the cross-linking degree on adhesive properties of PSAs, were studied. It was found that with the increase in telogen content in th... [more]

With the rapid development of high-pressure combustible gas pipelines, it brings convenience and also buries potential safety hazards. This paper presents an in-depth exploration of the thermal radiation hazards of fireball accidents caused by leakage and provides a reference for the prevention and control of this type of accident and on-site rescue. Based on the basic principle of fluid mechanics and the calculation model of the leakage rate, a three-dimensional pipeline model was constructed by FDS software to simulate the fireballs with different positions of low, middle and high. The simulation shows that the ground temperature field of the low and middle fireballs is quite different from that of the high fireball, and the temperature level is: low position > middle position > high position. On this basis, the observation elevation angle is introduced to improve the classical fireball thermal radiation model formula, the model calculation value is compared with the numerical simula... [more]

This paper proposed a gas emission prediction method based on feature selection and improved machine learning, as traditional gas emission prediction models are neither accurate nor universally applicable. Through analysis, this paper identified 12 factors that affected gas emissions. A total of 30 groups of typical data for gas outflow were standardized, after which a full subset regression feature selection method was used to categorize 12 influencing factors into different regular patterns and select 18 feature parameter sets. Meanwhile, based on nuclear principal component analysis (KPCA), an optimized gas emission prediction model was constructed where the dimensionality of the original data was reduced. An optimized algorithm set was constructed based on the hybrid kernel extreme learning machine (HKELM) and the least squares support vector machine (LSSVM). The performance of feature parameters adopted in the prediction algorithm was evaluated according to certain metrics. By com... [more]

The objective of this study was to assess the impact of pulsed electric field (PEF) treatment on the extraction of polyphenolics and antioxidant activity from downgraded date palm fruits. The PEF pretreatments (frequency: 30 Hz, time: 50 μs, pulse number: 240, the electric field strengths were found to be 1, 2, and 2.5 kV.cm−1, and methanol (50%) and temperatures (20, 40, 50 °C)) were optimized and applied before extraction to produce an extract of date fruits with a high content of bioactive compounds. The extracts obtained immediately after pretreatments were analyzed for total polyphenolic content, antioxidant activity, and phenolic profiles. The results revealed that the PEF-assisted extracts at 2.5 kV.cm−1 at T50 °C exhibited higher polyphenol content (+27%) and antioxidant activity (+31%) and notably improved phenolic profiles compared to untreated extracts. PEF treatment processing significantly enhanced the bioactive components and antioxidant activities of date fruits over tim... [more]

The surface integrity of machined components is considered to be an important part of the quality matrix for high-performance applications in the aviation industry. Therefore, close attention is given to the components made up of hard-to-cut materials such as Ti6Al4V, which face processability challenges. In this regard, among the non-conventional machining processes, electric discharge machining is widely preferred for cutting Ti6Al4V. In this study, the potentiality of cryogenic-treated tool electrodes (graphite and aluminum) with unmodified (kerosene) and modified (kerosene with Span 20, Span 60, and Span 80) dielectrics are comprehensively investigated. A three-phased experimentation framework is deployed based on the following process parameters, i.e., surfactant type, surfactant concentration, electrode material, and pulse ON:OFF time. Thorough statistical analyses are performed based on the full factorial design of experiments, and the results are characterized by process physic... [more]

The use of coal as a source of energy is crucial for the growth of the national economy, but mining poses numerous risks and a potential for significant disasters. Coal mine safety is the prerequisite and guarantee for coal industry to achieve new industrialization and sustainable development. Therefore, it is crucial to predict a safety accident in the coal mine in advance. In order to facilitate the early warning of coal mine safety accidents, this study seeks to present a prediction model based on emergency management of safety accidents, which is a fusion model of principal component analysis (PCA) and long short-term memory neural network. According to the results, the correlation coefficients of risk identification and monitoring (a11), safety inspection and warning (a12), emergency planning and training (a13), material and technical support (a15), and macroenvironmental management (a21) were 0.718, 0.653, 0.628, 0.444, and 0.553, respectively, after the PCA dimensionality reduct... [more]

Diabetes is one of the main health issues worldwide because of its lifetime duration. To overcome this health problem, the current study was conducted. This investigation aims to explore the α-glucosidase and β-secretase potential of extract/fractions and pure isolated compounds of Syzygium cumini bark. The chloroform extract of Syzygium cumini bark was subjected to chromatographic analysis to yield compound 1. The structure of isolated phytochemical (1) was conducted using advanced spectroscopic analysis. Among test extracts, the chloroform fraction exhibited a significant effect against α-glucosidase with a % activity of 86.20% and an IC50 of 77.09 µM, while the isolated compound exhibited a promising effect with a % activity of 91.54 and an IC50 value of 17.54 μM. The extract/fractions and isolated compound 1 also showed promising effects against the β-secretase enzyme, having % effects of 83.21 and 91.54% with IC50 values of 318.76 and 17.54 μM, respectively. The extract/fractions... [more]

With the increased demand for sustainable, hypoallergenic products, plant surfactants are a promising, eco-friendly option for cleaning products due to their low toxicity or even the absence of toxicity. In the present study, surfactant-rich extracts from Chenopodium quinoa, Glycine max, and Malpighia emarginata were assessed for their stability, antioxidant capacity, toxic potential, and cleaning potential in shampoo formulations. The surfactants in the extracts were isolated and characterized by NMR, UV-Vis, and FTIR spectroscopy. The results demonstrated that the extracts remained stable within the temperature and pH ranges tested. The antioxidant properties were also determined. In the analysis of irritation potential, G. max and C. quinoa exhibited low toxicity and no toxicity, respectively. The cleaning potential analysis confirmed that the extracts could be used as primary surfactants. Seven shampoo formulations were developed, which showed potential to reduce surface tension to... [more]

During the last decades, palladium nanoparticles (Pd(0) NPs) and Pd(II) compounds were shown to be attractive catalysts for fine organic synthesis. Nanostructured Pd(0) or Pd(II) catalysts have a relatively low environmental impact, but, at the same time, they are indispensable for such processes as Suzuki cross-coupling. This paper describes the preparation of Pd(0) or Pd(II) supported/embedded in hyper-cross-linked polystyrene (HPS) and compares their activity in Suzuki cross-coupling between phenylboronic acid and 4-bromoanisole. Obviously, the palladium charge (Pd(0) ↔ Pd(II)) changes continuously during the reaction catalytic cycle. It would seem that the use of the starting palladium in the form of Pd(0) or Pd(II) should not affect the reaction’s kinetic laws for both catalysts, but their special individuality is manifested between them. Nanoparticulate Pd(0) catalysts are stable during the reaction. In contrast, catalysts based on Pd(II) are extremely active in the initial perio... [more]

The application of biopolymers and feasible technologies to obtain sheets is crucial for the large-scale production of food packages and for reducing plastic pollution. Additionally, the inclusion of additives in sheets can affect and improve their properties. This work aimed to incorporate tucumã oil (TO) and TO microparticles produced by spray drying (SD), spray chilling (SC), and their combination (SDC) into extruded cassava starch sheets and to evaluate the effect of such addition on their physical, optical, and mechanical properties. Gum Arabic and vegetable fat were used as wall materials for SD and SC/SDC, respectively. The sheets enriched with tucumã oil (FO) and the microparticles produced by SD, SC and SDC (FSD, FSC, and FSDC, respectively) presented yellow color (hue angle around 90°) and higher opacity (11.6−25.3%) when compared to the control (6.3%). All sheets showed high thickness (1.3−1.8 mm), and the additives reduced the water solubility of the materials (from 27.11%... [more]

Sandstone oil−gas reservoirs in the Junggar Basin, China have great development potential. However, their ultra-deep formation depth leads to high crustal stress and high breakdown pressure. Therefore, in this research, we studied the cyclic hydraulic fracturing of tight sandstone with different combinations of “high-pressure duration + low-pressure duration” under high-stress conditions. Through laboratory experiments, the pump pressure curves, hydraulic fracture morphology, acoustic emission counts, and peak frequency of the samples were obtained. The results showed that: (1) Compared with conventional hydraulic fracturing, the breakdown pressure of cyclic hydraulic fracturing was reduced by more than 30%, the minimum threshold of cyclic pump pressure required for sample breakdown was between 60%Pb and 70%Pb, and cyclic hydraulic fracturing more easily formed complex and diverse hydraulic fractures. (2) In cyclic hydraulic fracturing, under the same upper limit of cyclic pump pressur... [more]