Search

A diazirine-based four-armed cross-linker (4CNN) with a tetrahedron geometry is presented for efficient patterning of polymeric semiconductors by photo-induced carbene insertion. After blending of 4CNN with no more than 3 % (w/w), photo-patterning of p-, n-, and ambipolar semiconducting polymers with side alkyl chains was achieved; regular patterns with size as small as 5 μm were prepared with appropriate photomasks after 365 nm irradiation for just 40 s. The interchain packing order and the thin film morphology were nearly unaltered after the cross-linking and the semiconducting properties of the patterned thin films were mostly retained. A complementary-like inverter with a gain value of 112 was constructed easily by two steps of photo-patterning of the p-type and n-type semiconducting polymers. The results show that 4CNN is a new generation of cross-linker for the photo-patterning of polymeric semiconductors for all-solution-processible flexible electronic devices.

A fluorescent probe based on the functionalized carbon quantum dots (CQDs-OPD) was successfully synthesized for selective and sensitive detection of Cu2+. Using O-phenylenediamine (OPD) as the carbon resource and N,N-dimethylformamide (DMF) as the solvent, the CQDs-OPD was prepared by the hydrothermal method. The fluorescence mechanism of CQDs-OPD was studied by the intercept method. Furthermore, the probe was characterized by TEM, UV–Vis, FT-IR and Zeta potentiometric analysis, the fluorescent probe exhibits a good fluorescence properties and stability. The prepared ratio-fluorescent probe shows a good linear range from 0 to 25 μmol/L with a lower LOD of 40 nmol/L. Moreover, the probe also has been successfully applied to the detection of Cu2+ in the real samples with the recovery rate of 96.92–97.80% and the RSD of less than 2.0%.

When compressing a soft bellow, the bellow will contract and pump out the fluid inside the bellow. Utilizing this property, we propose a novel actuation method called compressing bellow actuation (CBA), which can output fluidic power and tendon-driven force simultaneously. Based on the CBA method, a double-acting soft actuator (DASA) combining fluidic elastomer actuator (FEA) and tendon-driven metacarpophalangeal (MCP) joint is proposed for robotic finger design. The proposed DASA exhibits both compliance and adaptiveness of FEAs, and controllability and large output force of the tendon-driven methods. The fluid in the bellow can be either air or water or even integration of the two, thus constituting three different actuation modes. Mathematical modeling of the relationship between bellow compression displacement and DASA’s bending angle is developed. Furthermore, experimental characterizations of DASA’s bending angle and blocking force are conducted at different actuation modes. The double-acting method can availably promote the bending angle of an FEA by up to 155%, and the blocking force by up to 132% when the FEA is water-filled. A soft robotic hand with a forearm prototype based on the DASA fingers is fabricated for the demonstration of finger motion and gripping applications.

The transmission capacity of gas pipeline networks should be calculated and allocated to deal with the capacity booking with shippers. Technical capacities, which depend on the gas flow distribution at routes or interchange points, are calculated with a multiobjective optimization model and form a Pareto solution set in the entry/exit or point-to-point regime. Then, the commercial capacities, which can be directly applied in capacity booking, are calculated with single-objective optimization models that are transformed from the above multiobjective model based on three allocation rules and the demand of shippers. Next, peak-shaving capacities, which are daily oversupply or overdelivery amounts at inlets or deliveries, are calculated with two-stage transient optimization models. Considering the hydraulic process of a pipeline network and operating schemes of compressor stations, all the above models are mixed-integer nonlinear programming problems (MINLPs). Finally, a case study is made to demonstrate the ability of the models.

To cope with the global food shortage and insect pest, there is an urgent need to discover new pesticides with novel modes of actions. Ryanodine receptor (RyR) insecticides showed great promise in ...

In this paper, a novel systematic and integrated methodology to assess gas supply reliability is proposed based on the Monte Carlo method, statistical analysis, mathematical-probabilistic analysis, and hydraulic simulation. The method proposed has two stages. In the first stage, typical scenarios are determined. In the second stage, hydraulic simulation is conducted to calculate the flow rate in each typical scenario. The result of the gas pipeline system calculated is the average gas supply reliability in each typical scenario. To verify the feasibility, the method proposed is applied for a real natural gas pipelines network system. The comparison of the results calculated and the actual gas supply reliability based on the filed data in the evaluation period suggests the assessment results of the method proposed agree well with the filed data. Besides, the effect of different components on gas supply reliability is investigated, and the most critical component is identified. For example, the 48th unit is the most critical component for the SH terminal station, while the 119th typical scenario results in the most severe consequence which causes the loss of 175.61 × 104 m3 gas when the 119th scenario happens. This paper provides a set of scientific and reasonable gas supply reliability indexes which can evaluate the gas supply reliability from two dimensions of quantity and time.

Real-time flow estimation plays a vital role in multi-product pipeline operations, and the accuracy of real-time flow estimation is affected by noise interference and instrument accuracy and cannot be performed by direct observation of flow meter. Pipeline flow models based on the first principle method are established and employed as soft sensors of pipeline real-time flow rate. However, these models are validated by the controlled experimental pipeline, which may be ineffective regarding actual pipelines with uncertain physical parameters. In this paper, a novel approach integrating data-driven and model-driven method is proposed to estimate the flow rate of petroleum products on-line. The difference between the theoretical model and actual state of a pipeline is accounted for by the friction coefficient, and on-line calibration is achieved by solving multi-objective optimisation problems with asynchronous operation data. The flow state of the pipeline is obtained in real time by the particle filter when new pressure observations with noise become available. The estimation performance of local pressure mutation points is improved by adopting the recurrent nonlinear autoregressive neural network modelling blue of the data-driven method. The effectiveness of the proposed method is evaluated blue by examining actual data of the pipeline over a period of time. The prediction results of some other model-driven and data-driven methods are also compared to blue that of the proposed method. The results blue indicate that the proposed method improves the accuracy and reliability of the product flow rate estimations even under unforeseen operation conditions.

In recent years, with the goal of “carbon peaking and carbon neutralization”, the CO2 flooding technology in carbon capture, utilization, and storage (CCUs) has been paid great attention to the oil fields. However, the CO2 flooding of crude oil may produce foams in the oil and gas separation process. In addition, the precipitation of wax components in crude oil might enhance the stability characteristics of these foams and lower the separator’s efficiency. Based on a crude oil depressurization foaming device, the influence of wax crystals on the bursting of oil foam was studied using simulated oil, and the microstructure of the wax crystal and foam liquid film was observed using freeze-etching and microscopic observation. In addition, the gas–liquid interface model of the wax oil was established by a molecular dynamics (MD) simulation to analyze the influence mechanism of wax crystals on foam drainage and gas diffusion among foams in the microlayer. The results show that the precipitation of wax crystals overall reduces the rate of defoaming and drainage and increases the grain diameter of the foam. The formation and growth of the wax crystal-shaped network impede the flow of liquid in the drainage channel and stabilize the foam. Moreover, it impedes the diffusion of CO2 among foams, inhibiting the bursting of the foams. The results of the combined experiments and MD simulation verify the accuracy and applicability of the molecular model, which further clarifies the effect of wax crystals on foam stability and its mechanism of action on foam film. These findings are a benchmark for the enhancement of defoaming and separation efficiency and a theoretical framework for future study and modeling.

The compliance of conventional granular jamming universal grippers is limited due to the increasing friction among particles when enveloping an object. This property limits the applications of such grippers. In this paper, we propose a fluidic-based approach for universal gripper which has a much higher compliance compared to conventional granular jamming universal grippers. The fluid is made of micro-particles suspended in liquid. Jamming transition of the dense granular suspension fluid from a fluid (hydrodynamic interactions) to solid-like state (frictional contacts) in the gripper is achieved by external pressure from the inflation of an airbag. The basic jamming mechanism and theoretical analysis of the proposed fluid is investigated, and a prototype universal gripper based on the fluid is developed. The proposed universal gripper exhibits advantageous compliance and grasping robustness in sample grasping of delicate objects, such as plants and sponge objects, where the traditional granular jamming universal gripper fails.

An innovative molecular imprinted polymer based on KH-570 modified SiO2-coated cadmium telluride quantum dots was prepared as fluorescence sensor for sulfadimidine (SM2) sensitive and selective detection. The quantum dots were firstly encapsulated in silica by sol–gel process, and then the double bond was modified on the surface of silica with KH-570. Finally, the molecular imprinted layer was synthesized on the surface of silica by template molecule, methacrylic acid (MAA) and ethylene glycol dimethyl acrylate. The fluorescence sensors showed good structure when characterized by SEM. Besides, the fluorescence sensors showed a good linear range from 10 to 80 μmol.L−1 with a lower LOD of 0.42 μmol.L−1. These sensors were successfully applied to detect SM2 in the water samples with a recovery rate from 91.6% to 97.8% and the relative standard deviation less than 2.5%, indicating that fluorescence sensors have the potential application in the detection of real samples.

In this paper, a new methodology is proposed to realize real-time unsteady flow estimation for a multi-product pipeline system. Integrating transient flow model, adaptive control theory, and adaptive filter, this method is developed to solve the contradiction between the efficiency and accuracy in traditional model-based methods. In terms of improving computational efficiency, the linear flow model based on frequency response and difference transforming is established to replace the traditional nonlinear flow model for transient flow state estimation. To reduce the deviation between actual observations and linear model estimates, we first introduce a model-free adaptive control method as linear compensation of the reduced order unsteady flow state model. To overcome the interference of observation noise, the Kalman filter method is applied to the modified state space model to obtain the one-step-ahead transient flow estimation. The proposed method is applied to the transient flow state estimation of a multi-product pipeline system and compared with the model-based method and two data-driven methods. The proposed method can reduce the deviation of transient flow estimation between the reduced order linear model and the traditional nonlinear model to less than 0.5% under unforeseen conditions and shows strong robustness to noise interference and parameter drift.

Background. Autogenous tooth transplantation is a reliable method for repairing missing teeth. Although it recently became a recognized and feasible treatment method in dentistry, the long-term efficacy of root canal therapy (RCT) has not been well confirmed. This study is aimed at determining whether RCT has a good effect on the success rate of teeth with complete roots in autogenous tooth transplantation. Materials and Methods. Data were collected from the Korea University Guro Hospital. Data of patients who underwent autogenous tooth transplantation within 9 years were collected. We selected 29 teeth with complete roots as the research subjects in our study. None of the patients had any systemic diseases. All cases in this study were obtained with patient permission. Results. According to the tooth vitality test, the autogenous teeth tested negative in dental pulp test and function. Nine of the 29 teeth with autogenous tooth transplantation were treated with RCT and survived throughout the observation period. However, 20 autogenous teeth were not treated with RCT, and eight of them did not survive. All statistical analyses were performed using IBM SPSS 20.0. The null hypothesis was rejected ( p < 0.05 ). Conclusion. For complete root teeth, the success rate after autogenous tooth transplantation after RCT is higher than that of teeth not treated with RCT.

This paper proposes a digital twin solution for unsteady flow state estimation in a pumping station. Digital twin is expected to accurately estimate the real-time hydraulic parameters of blind spots of the pumping station system even under some adverse conditions including the interference of observation noise and model parameters drift. To solve these challenges, a digital twin framework integrating the model-driven method, control theory and data-driven method is presented. In this framework, an unsteady flow state estimation method combining frequency domain analysis and generalized predictive control theory is developed for the first time, which is superior to traditional time-domain numerical discrete methods in terms of computational efficiency and anti-noise interference. In the model parameter calibration process, the novelty concerns modeling of the optimization problem considering the dynamic operation control of the station and unsteady flow of pipelines. And this process is accomplished through the comprehensive application of the model-free adaptive control algorithm, the transient flow model and the particle swarm optimization algorithm. This work is applied to a pumping station in a product pipeline to verify its effectiveness in estimating the transient flow state of data blind spots and map the dynamic operation behavior under the interference of colored noise and parameter drift.

To cope with the global food shortage and insect pest, there is an urgent need to discover new pesticides with novel modes of actions. Ryanodine receptor (RyR) insecticides showed great promise in integrated pest management. Herein, we report the synthesis of novel anthranilic diamide derivatives incorporating pyrrole moieties targeting at insect RyRs. The structures were confirmed by

This paper addresses how to optimize detailed schedules of a multiproduct pipeline network. A continuous-time mixed integer linear programming (MILP) formulation is developed to seek the minimum makespan of transportation tasks. Operation constraints about sequence of products, size of single-product batches, flow rate of delivery and injection operations, pumping rate of pipeline segments, batch tracking, conditions of implementing injection or delivery operations, inventory management of stations and consumer markets’ demand are all satisfied. The MILP formulation is illustrated by three pipeline networks. Results show the proposed MILP model has a better performance than previous works.

The fluorescence mechanism of dual-emission carbon quantum dots (DCQDs) is investigated by the improved intercept method, of which the DCQDs with high quantum yield are synthesized by hydrothermal method by using the precursor of sulfadiazine. The research of the morphology, chemical properties and fluorescence properties on DCQDs, shows that DCQDs have graphene-like structure and well-resolved lattice fringes, and that DCQDs fluorescence emission as well intensity has reversibility between acid and alkaline. Based on the ultraviolet absorption spectrum (UV–vis) of the DCQDs, the band gap of DCQDs is estimated by the improved intercept method. Then, the change law of DCQDs emission wavelength at different excitation wavelengths is studied by using the estimated band gap. It is found that the improved intercept method is well consisted with the emission change law of DCQDs at different excitation wavelengths. In addition, the influence of different concentration of Fe3+ on the estimated band gap of DCQDs shows that the Fe3+ has big influence on the band gap of 3.99 eV and 3.06 eV but almost no effect on band gap of 4.93 eV and 3.67 eV. It indicates that the quenching of Fe3+ to DCQDs may be due to the band gap caused by surface defect is changed by Fe3+. Also, DCQDs are used as probe to detect Fe3+ and used as spray ink. Thereby, the improved intercept method may provide a new direction for researching the fluorescence mechanism of carbon quantum dots.

Waxy crude oil exhibits shear-dependent and time-dependent thixotropic behavior below the threshold temperature. Various models have been proposed to describe this type of behavior in previous lite...

When several kinds of crude oil need to be transported, the batch pipelining is a better choice than the “single-pipeline-single-oil” and blending pipelining due to its advantages. In the batch pipelining process, to avoid the frequent operations on the pumps and control valves, the flow rate is generally inconstant in practice. All previous studies simplify the flow rate distribution as a constant one, which largely deviates from the engineering practice. Focused on this point, based on the features of the batch pipelining in practice, the gradient-type flow rate distribution model and corresponding calculation approach are proposed in this paper. The accuracy of this model and corresponding calculation approach are verified by the field data, and it indicates that the accuracy of numerical results can meet the engineering requirement. Further, the thermal characteristics of the batch pipelining are found by numerical simulation and the further analysis is carried out to make these characteristics more convincing. Finally, the shortcoming of the step-type flow rate distribution with simple expression is pointed out. It is found that the adoption of the step-type flow rate distribution in the simulation would introduce a prominent deviation when the change period of flow rate is relatively long. To overcome this shortcoming, the proposed gradient-type flow rate distribution, whose accuracy is higher, is an alternative method.

In this paper, a double-pipe heat exchanger with a series of corrugated tubes as inner tubes is studied for the adequate cooling of thermal-hydrolyzed sludge. A numerical model, built on the Spalart-Allmaras model, is validated to have the ability for characterizing the flow and heat transfer performance of sludge. The influencing factors, including the flow parameters of the sludge and cooling water, and the geometric configurations of the corrugated tube are parametrically investigated. The ratio of Nusselt number (Nu/Nu0), the coefficient of flow resistance (f/f0) of the sludge, the synthesis factor of performance (η) and the ratio of the heat transfer increase over the pump power increase ( ζ ) are used as the performance assessment indexes. The results show that increasing Resludge can negatively affect η and η tends to be stable when Rewater is higher than 1.2 × 104. Decreasing S/D and increasing H/D result in a higher ratio of flow resistance f/f0 and a higher ratio of Nu/Nu0. The corrugation height (H) shows a larger effect than the corrugation length (S). In practical applications, the optimal flow rates of the sludge for the studied corrugated tubes are recommended to be within the range of 1.2–1.5 m/s.

CO2 flooding crude oil may generate abundant foams in oil field separators after depressurization. A large amount of foams occupies most of the space in a separator and spends much time to burst, which, in turn, reduces the separation efficiency of the separator. Moreover, the incomplete gas-liquid separation will cause corrosion in the downstream pipeline, and damage both the pump and the compressor. Based on the self-development crude oil depressurization foaming device and the CO2 flooding crude oil, this paper studies the evolution of foam and analyzes the function mechanism of asphaltene and wax crystal on defoaming and drainage of crude oil quantitatively. The experimental results show a law that the rate of defoaming and drainage increase at the initial stage and then decrease, which is available for different crude oils. So, the paper proposes a kinetics model of the defoaming and drainage based on the three-degree polynomial function innovatively, which not only describes the evolution of foam volume, but also indicates the change of foam drainage rate. Meanwhile, the experiments found that asphaltene promoted the stability of foams by being adsorbed on foam film in the process of liquid drainage. Wax crystal reduced the fluidity of drainage, which decreased the defoaming and discharging rate. But the wax crystal with specific structures reduced the stability of foams. It is significant to explore the foaming and defoaming mechanism of crude oil for providing references for the improvement of separator efficiency and the development of separation technology.

The effect of nonionic surfactant (Tween 80) concentration on the evolution of drop size distributions (DSDs) of oil/water dispersion in a stirred tank was investigated experimentally and numerically. It was found that as the surfactant concentration increases, the mean droplet size decreases, the number density of small droplets increases and the dispersion stability is enhanced. It could be attributed to the augmentation of the breakage frequency caused by a dramatic reduction of interfacial tension and the suppression of the coalescence efficiency by an immobilized interface. When applying population balance equation (PBE) to surfactant dispersions, the effect of surfactant concentration was characterized by its influence on both breakage and coalescence process. The combined effect of surfactant molecules, drop size, and the number density of droplets on the turbulence intensity was considered in the breakage model. Models of coalescence time that consider partially mobile and immobile interfaces were employed to describe the film drainage at surfactant concentrations below and above CMC (critical micelle concentration) respectively. The effect of surfactant concentration on the critical film thickness was probed by adjusting the Hamaker constant and measuring the interfacial tension, while its influence on the coalescence efficiency was investigated by further balancing the contact and coalescence time. Both the predicted Sauter mean diameter and cumulative DSD agree with the experimentally measured values at different surfactant concentrations, while the discrepancies that exist could be due to the underestimation of coalescence rate between small droplets.

Recently, spinel ferrites have attracted much attention due to their various redox states, great electrochemical stability, and pseudocapacitive behavior. Herein, NiFe 2 O 4 /MoS 2 composite material with excellent electrochemical properties was smart-designed and successfully synthesized via a facile solution reaction and freeze-dried process for the first time. The composite combines the advantages of both MoS 2 nanosheets and NiFe 2 O 4 nanoparticles, showing enhanced capacitive performance than MoS 2 nanosheets and NiFe 2 O 4 nanoparticles and surpassed some of the previously reported materials. A maximum specific capacitance (506 F/g at 1 A/g) of NiFe 2 O 4 /MoS 2 composite was obtained, and the electrode can kept over 90.7% (at 5 A/g) of capacitance after 3000 cycles. The excellent electrochemical performance is attributed to the synergistic effect of MoS 2 nanosheets and NiFe 2 O 4 nanoparticles. Moreover, this complex material could be used in other advanced energy storage and conversion systems, such as Li-ion batteries, Li-air batteries, Na-ion hybrid capacitors, hydrogen evolution reaction catalysts, etc.

A multiproduct pipeline is an economical way for transporting several products from a single source to multiple delivery stations over a long distance. This paper addresses how to optimize detailed schedules of a multiproduct pipeline. A discrete-time mixed integer linear programming model is developed, which adopts a novel objective function to seek the minimum summation of pumping rate variations in every pipeline segment along a pipeline during a scheduling horizon. The feasibility of the new objective function is demonstrated in theory. A conclusion is drawn that the more stable pumping rate of a pipeline segment is, the lower frictional loss for pumping products is. Besides operational constraints, two sets of special constraints are introduced into the model for improving the operability and practicability of detailed schedules. One is the stopping and running duration limitations of injection operations and another one is the flow rate stability requirements of injection and delivery operations. The proposed MILP model is successfully tested on two real world multiproduct pipelines using CPLEX as solver.

For the purpose of investigating the effect of dispersed phase on turbulence characteristics, both CFD simulation and experiments from particle image velocimetry (PIV) on flow field at different dilute liquid-liquid dispersion are performed. CFD simulation is established by coupling mixture model and empirical mean drop size for two phase mixing. Turbulent kinetic energy (TKE) and energy dissipations rate (EDR) are discussed as key parameters. With the addition of dispersed phase, CFD results indicate that TKE decrease when EDR increase in impeller region and both decrease in circulation region; while experimental results shows both TKE and EDR increase in the full flow range. Trend reflected from CFD results is supposed to be the suppression on velocities fluctuation by enlarged density and viscosity of the dispersed phase, and the enhancement of energy dissipation rate by viscosity. Further work concerning the dynamics of drop distribution evolution (coupling Population Balance Equations, PBE) in CFD simulation is particularly demanded, where the effect of drop behaviors including random motion, breakage and coalescence on turbulence intensity could be discussed.

Due to new mechanism of action and ecofriendly characteristics, dicarboxamide insecticides have attracted more and more attentions in modern pest management. A series of 20 dual chiral N-cyano sulfilimines containing two centers (carbon and sulfur) were designed and synthesized. All title compounds were determined by 1H NMR, high-resolution mass spectrometry (HRMS) and optical polarimeter. The preliminary results indicated that some of them exhibited favourable insecticidal activities against oriental armyworm (Pseudaletia separata Walker). These isomers exhibited different impact on activity following the sequence as (Sc, Ss) ≥ (Sc, Rs), and the rule of title compounds’ activity against oriental armyworm was 3-CF3 ≥ 2 CH3 4 Cl >2, 3, 4-trifluro in the anilide moiety. The results indicated that these groups such as 3-CF3, 2 CH3 4 Cl or 2, 3, 4-trifluro were inefficient to replace heptafluoroisopropyl group for high larvicidal activity, which provided some guidance for the further modifications of sulfiliminyl dicarboxamides.

In order to search for novel potent and environmentally benign insecticides, a series of anthranilic diamides containing various fluorinated groups were designed and synthesized. Their structures were confirmed by 1 H NMR, 13 C NMR, 19 F NMR, elemental analysis, HRMS or mass spectra. Their insecticidal activities against oriental armyworm ( Mythimna separata ) and diamondback moth ( Plutella xylostella ) were evaluated. The preliminary structure-activity relationship (SAR) was discussed in detail. The biological assay indicated that most of the compounds exhibited moderate to excellent insecticidal activities. Especially, Ia showed high larvicidal activity against oriental armyworm. Meanwhile, Iu had better larvicidal effects against diamondback moth than commercial chlorantraniliprole.

This paper addresses the optimization of delivery/injection plans of intermediate stations along a unidirectional multiproduct pipeline. A mixed-integer linear programming (MILP) model is developed to minimize pump rate variations in every pipeline segment along the pipeline during a specific scheduling horizon. Given the problem complexity, a computational framework is proposed consisting of three main stages: initial solution finding, solution improvement based on a simulated annealing (SA) metaheuristic, and solution refinement based on tailor-made heuristics. The algorithm for making an initial solution is based on a so-called space recursive method that the delivery/injection schedule of every intermediate station is gradually generated from upstream to downstream segments. The algorithm for generating a new solution by SA consists of three steps: selecting an intermediate station, choosing a batch passing by the selected station, and adjusting the selected operation. For improving the quality of sol...

Measurement of dispersed modality at different spatial locations is performed in a 1000 ml borosilicate beaker at various dispersed volume fractions in both W/O and O/W system. It is found that mean chord length at different spatial locations shows a similar distribution in both W/O and O/W dispersion that the closer to impeller the smaller the mean chord length. Further, in dilute W/O dispersion (3%), results show that both number counts and mean chord length of droplets at impeller region are smaller than other locations; however, it gradually turns to be larger at higher dispersed fraction (20%). For O/W dispersion, it is found that number counts of small droplets in region around impeller become smaller than other locations with the addition of dispersed oil phase (10%). Flow characteristic measured by 2D angle-resolved particle image velocimetry in pure oil/water phase is employed to further explain the deviation. Besides, the critical dispersed fraction affecting the dispersed modality at different spatial location is discussed.

Background: Magnesium (Mg) is essential to many plant physiological and biochemical processes; however, a quantitative understanding of how Mg nutrition affects the production, partitioning and utilization of photoassimilates is still lacking, especially for soilless culture system. We focused on the roles of Mg in yield formation and interactions with potassium (K) nutrition of cherry tomato. Cherry tomato yield, leaf Mg concentration, photosynthetic parameters, dry matter weight and K, Mg and calcium (Ca) uptake were investigated in two soilless experiments with seven Mg levels and five K levels.Results: Low (4 mM) Mg supply limited cherry tomato yield by decreasing 22.6-78.1% dry matter accumulation and 13.9-40.7% harvest index. The critical leaf Mg concentrations required for adequate photosynthate production in the first and second harvest periods were 4.67 and 5.52 g kg –1 , respectively. But over-supply of Mg disturbed leaf K and Ca concentrations, limiting the plant K and Ca content. Moreover, adjusting K concentrations in solution is a crucial factor influencing plant Mg functions, and therefore cherry tomato growth.Conclusion: Balanced Mg and K application increased Mg, K, and Ca uptake by cherry tomato, as well as Mg concentrations in leaves which could maintain a sustainable photosynthetic rate and plant dry matter formation.

As one of the most important means of nature gas peak shaving and energy strategic reserving, the reliability assessment of underground gas storage (UGS) system is necessary. Although many methods have been proposed for system reliability assessment, the functional heterogeneity of components and the influence of hydrothermal parameters on system reliability are neglected. To overcome these problems, we propose and apply a framework to assess UGS system reliability. Combining two-layer Monte Carlo simulation (MCS) technique with hydrothermal calculation, the framework integrates dynamic functional reliability of components into system reliability evaluation. To reflect the state transition process of repairable components and their impact on system reliability, the Markov model is introduced at system level. In order to improve the calculation speed, artificial neural network (ANN) model based on off-line MCS is established to replace the on-line MCS at components level. The proposed framework is applied to the reliability assessment and operation optimization of an UGS under different operation conditions. Compared with the traditional single-layer MCS method, the proposed method can not only reflect the variation of UGS reliability with hydrothermal parameters and operation time, but also can improve evaluation efficiency significantly.

An integrated methodology to assess the gas supply reliability of a gas pipeline network considering stochastic demands is proposed in this study. Typical scenarios are selected based on the structural reliability calculated by probability theory and stochastic process, including the normal scenario and some failure scenarios with a high probability. For each specific scenario, the gas supply condition is assessed based on the Latin hypercube sampling with the Cholesky decomposition method under stochastic demands. The maximum flow method based on the Dijkstra algorithm is adopted to determine whether the gas demand of customers can be fully covered and optimize the supply scheme under shortages. Finally, the assessment results are demonstrated from the following four aspects: the probability distribution of gas shortages under the normal scenario, identification of units with a high failure probability and vulnerable units, the reasons of gas supply shortages and corresponding probabilities, and the probability distribution of supply reliability for a gas pipeline network and each customer. The methodology is applied to a large-scale gas pipeline network in China. The results of the supply reliability assessment are analyzed in detail, and the sensitivity analysis of the gas demand uncertainty level on gas supply reliability is conducted.

Asphaltenes are the most polar components of crude oils. The influences of asphaltene polarity on the wax deposition were studied in this investigation using model waxy oils. Asphaltenes contained by a Venezuelan crude oil were fractionated into four subfractions of different polarity utilizing a liquid/liquid extraction technique and used to prepare asphaltene-containing waxy model oils. The mass, composition, dielectric characteristics and mechanical characteristics of the waxy deposits formed in the presence of asphaltene fractions of different polarity were characterized. It was found that the less polar asphaltenes in waxy oils lower the deposit mass but cause the wax content of the deposits to increase. In addition, the inner diffusion of longer n-alkanes and the outer diffusion of shorter n-alkanes are accelerated by the less polar asphaltenes. Furthermore, the waxy deposits formed with waxy oils containing less polar asphaltenes are enriched with less amount of asphaltene and present reduced internal effective diffusion coefficient as was characterized by NMR. Besides, the presence of less polar asphaltenes causes the radius of Nyquist diagram of waxy deposits to increase, indicating higher resistance. Eventually, rheological characteristics, such as gelation temperature and yield stress, suggest increased structural strength of waxy deposits formed in the presence of less polar asphaltenes.

In order to discover potential ryanodine receptor insecticides, 21 novel anthranilic diamides analogues (C, D, E, and F) containing amide, carbamate, urea, and thiourea moieties were designed and synthesized based on bioisosteric approach. The biological assays against oriental armyworm (Mythimna separata) and diamondback moth (Plutella xylostella) indicated that these compounds displayed moderate to excellent activities. Especially, compound D1 showed 100% larvicidal activities against oriental armyworm at 1.0 mg•L−1, equivalent to the standard chlorantraniliprole (100%, 1.0 mg•L−1). Moreover, the larvicidal activity of D1 against diamondback moth was 100% at 0.1 mg•L−1, more effective than that of chlorantraniliprole (90%, 0.1 mg•L−1). Therefore, D1 can be used as a new lead structure for the development of insecticidal agents. The preliminary structure-activity relationship showed that the introduction od carbamate groups into 4-position on the benzene ring of the N-phenylpyrazole moiety has a positive effect on the larvicidal activities.

In order to search for potent and environmental friendly insecticides with new modes of action, a series of pyranoside derivatives mimicking D-myo-inositol 1,4,5-trisphosphate (IP3) were designed and synthesized according to the bioisosteric approach. The biological assay indicated that most of the new compounds showed moderate to good insecticidal activities against oriental armyworm (Mythimna separata) and diamondback moth (Plutella xylostella). Especially, compound 5g displayed 80% larvicidal activity against oriental armyworm at 50 mg/L. Meanwhile, 5a showed 100% and 70% larvicidal activities against diamondback moth at 50 and 25 mg/L, respectively. To further explore the mode of action, calcium imaging technique was applied to study the effects of 5a, 5g, and 5i on the intracellular calcium ion concentration ([Ca2+]i) in central neurons isolated from Spodoptera exigua. The results indicated that the tested compounds released stored calcium ions from endoplasmic reticulum.

In this paper, utilising 2D angle-resolved particle image velocimetry (PIV), the flow field of a dilute aqueous-in-oil dispersion is experimentally studied in a stirring tank. Opacity during liquid–liquid mixing is eliminated by matching the refractive indices of both phases. Anisotropy of the turbulence flow field is analysed via the turbulent kinetic energy (TKE) and energy dissipation rate (EDR) obtained at different measuring angles. The influence of spatial resolution is compared and discussed. TKE and EDR are observed to increase with increment of dispersed phase fraction while a small range of disorder and fluctuation is observed in the impeller region. The effect of dispersed droplets should be attributed to the strengthened fluctuation of velocities and spatial differences. Further work concerning higher resolution and the disperse fraction is necessary.

To discover potent insecticides targeting ryanodine receptors (RyRs), a series of novel anthranilic diamides analogues (12a-12u) containing N-substituted phenylpyrazole were designed and synthesized. These compounds were characterized by (1)H NMR, (13)C NMR, and HRMS, and the structure of compound 12u was confirmed by X-ray diffraction. Their insecticidal activities indicated that these compounds displayed moderate to excellent activities. In particular, 12i showed 100 and 37% larvicidal activities against oriental armyworm (Mythimna separata) at 0.25 and 0.05 mg L(-1), equivalent to that of chlorantraniliprole (100%, 0.25 mg L(-1); and 33%, 0.05 mg L(-1)). The activity of 12i against diamondback moth (Plutella xylostella) was 95% at 0.05 mg L(-1), whereas the control was 100% at 0.05 mg L(-1). The calcium-imaging technique experiment results showed that the effects of 12i on the intracellular calcium ion concentration ([Ca(2+)]i) in neurons were concentration-dependent. After the central neurons of Helicoverpa armigera were dyed by loading with fluo-5N and treated with 12i, the free calcium released in endoplasmic reticulum indicated the target of compound 12i is RyRs or IP3Rs. The activation of RyRs by natural ryanodine completely blocked the calcium release induced by 12i, which indicated that RyRs in the central neurons of H. armigera third-instar larvae is the possible target of compound 12i.

A new design strategy for photoresponsive semiconducting polymer with tri-stable semiconducting states is reported by simultaneous incorporation of tetra-ortho-methoxy-substituted azobenzene (mAzo) and arylazopyrazole (pAzo) in the side chains. The trans-to-cis transformations for mAzo and pAzo groups can sequentially occur within the polymer thin film after sequential 560 and 365 nm light irradiation. Remarkably, the trans-cis isomerization of mAzo and pAzo groups can modulate the thin film crystallinity. Accordingly, the performances of the resulting field-effect transistors (FETs) can be reversibly modulated, leading to tri-stable semiconducting states after sequential 560, 365, and 470 nm light irradiation. Therefore, the device performance can be logically controlled by light irradiation at three different wavelengths. In addition, with light irradiation and device current as the input and output signals, the three-value logic gate by using single FET device can be successfully mimicked.

CO2 flooding effectively enhances the recovery of crude oil. However, a large amount of foam is generated in the separator when the produced oil releases gas due to depressurization, which reduces the separator capacity. To address the foaming problem, this paper provides some qualitative and quantitative insights by studying the effects of depressurization, resin, asphaltene, wax crystal and other factors on the foaming and defoaming characteristics of four crude oils. A set of experimental devices is developed to assess foaming during depressurization. The experimental results indicate that a larger pressure drop increases the amount of foam generated and the defoaming rate. The ratio of resin to asphaltene is closely related to the foaming and defoaming characteristics of crude oil, and the effect of asphaltene on foam stabilization is greater than that of resin. There is a threshold wax crystal content for affecting the foaming and defoaming characteristics of crude oil. A small amount of wax crystals accelerates foam bursting, but further increasing the wax crystal content stabilizes the foam. These results provide guidance and a reference for CO2 flooding technology, the improvement of separators and research on the foaming and defoaming mechanisms of crude oil.

A transient composition tracking method is developed for natural gas pipe networks. It adopts the control volume method for hydraulic simulation and a one-dimensional unsteady heat transfer model for thermal simulation. In order to model the junction in the network, a special grid is proposed to connect all adjacent pipes together. Under this grid, the momentum equation could be discretized by the first-order upwind scheme while the mass equation could be discretized just like an ordinary pipe node. To track the composition, the advective concentration equation is given for each component. Therefore, the gas composition in the pipe network could be predicted in real time and its influence on the calculation of property parameters could be taken into consideration. Based on these models, a transient composition tracking algorithm is developed for natural gas pipe networks. It consists of three parts: transient flow simulation, composition tracking and parameters calculation. Case studies show that the proposed method can provide reliable results for transient flow simulation. Compared with the measured data, the composition outcomes given by this method are also very accurate. In addition, the impact of injecting LNG/H2 into the pipe network is quite complicated and should be treated with caution.

Magnesium (Mg) is essential to many plant physiological and biochemical processes, however, understanding how Mg nutrition quantitatively affects the production, partitioning, and utilization of photoassimilates is still lacking, especially in soilless culture systems. We focused on the roles of Mg in yield formation and interactions with potassium (K) nutrition of cherry tomato. Cherry tomato yield, photosynthetic parameters, dry matter weight, and K, Mg, and calcium (Ca) uptake were investigated in two soilless experiments with seven Mg levels and five K levels. The results showed that low (&lt, 1 mM) and high (&gt, 4 mM) Mg supply limited cherry tomato yield by decreasing dry matter accumulation by22.6&ndash, 78.1% and harvest index by 13.9&ndash, 40.7%. The critical leaf Mg concentrations required for adequate photosynthate production in the first and second harvest periods were 4.67 and 5.52 g&middot, kg&minus, 1, respectively. However, over-supply of Mg reduced leaf K and Ca concentrations and limited plant uptake of K and Ca. Moreover, adjusting K concentrations in solution could influence plant Mg functions in photosynthesis and, therefore, cherry tomato growth. Overall, balanced Mg and K application increased Mg, K, and Ca uptake, as well as Mg concentrations in leaves, which could maintain a sustainable photosynthetic rate and plant dry matter formation.

It is the basic responsibility for pipeline companies to satisfy the gas demand of customers. A methodology is proposed to assess the short-term supply reliability of a gas pipeline system under demand variations in this paper. Based on the failure rate and repair rate of the pipe segments and compressor units obtained through historical operational data, the probability under different structural failure scenarios of a gas pipeline system is computed through the stochastic process and probability theory. Indices from aspects of adequacy, availability, and shortage rate are developed to reflect the supply reliability. To reflect the assessment results intuitively, the cumulative probability function is adopted to reflect the supply adequacy and availability, and the probability distribution is adopted to reflect the supply shortage rate during the assessment period. For all scenarios, supply reliability is calculated through batch transient hydraulic and thermal simulations of a gas pipeline system by Stoner Pipeline Simulator considering practical operational processes and legal constraints. The proposed methodology is performed based on the Trans-Asian gas pipeline A-B system, and the functions of cross-over valves on supply reliability of the Trans-Asian gas pipeline A-B system is studied.

Asphaltenes are the heaviest and most polar constituents of crude oils. The influences of asphaltene on wax deposition were investigated with model oils utilizing a Taylor-Couette device. The composition and rheological properties of the deposits and the chemical properties of the asphaltenes entrained in the deposits were analyzed. Three main observations were obtained: (a) Wax deposition rate decreases in the presence of asphaltenes while the wax content of the deposit increases. The carbon number distribution of the deposit and the critical carbon number of the deposition process were also observed to vary due to the presence of asphaltenes. (b) The asphaltene content of the deposit constantly increases as time elapses and eventually reaches several times higher than that of the original oil. The asphaltenes entrained in the deposits are of higher polarity and molecular weight than the asphaltenes originally present in the oil. (c) When the asphaltene content of the oil is above 0.2 wt%, deposits slough off frequently as asphaltenes alter the microstructure of the deposit and lower its yield strength.

Based on process principles and the operational features of crude oil pipelines, this research developed mathematical models to optimize steady-state pipeline operation, to apportion monthly flow into daily or hourly flow rates, and to predict monthly energy consumption. Corresponding algorithms were also developed. Because these models and corresponding algorithms are process-based, they are suitable for predicting monthly energy consumption of existing isothermal and hot crude oil pipelines. The predicted monthly energy consumption of crude oil pipelines depends on which flow distribution method is used, which pumping operation scheme is used and which heating operation scheme is used, with different flow distributions, different pumping and heating operation scheme yielding a range of monthly energy consumption predictions for a given transportation volume. The minimum monthly energy consumption can be determined from these predictions, and the interval of the predictions can indicate the extent to which the flow rate fluctuation affects pipeline energy consumption. Both of these findings can be used by pipeline operators to reduce the amount of energy needed to operate crude oil pipelines.

With the continuous development of offshore oil and gas resources, calculation software for multiphase flowing pipe network has become an important tool for the design and daily operation of multiphase flowing pipe network. Improved accuracy of hydraulic and thermal calculation is an engineering requirement for economic and efficient production. Therefore, a new program is developed for multiphase pipe network in this paper. This program contains a general data structure to describe the complex connection of a pipe network. The structure is based on the conception of the incidence matrix and the adjacency matrix in graph theory. Two processes, hydraulic equilibrium calculation and thermodynamic equilibrium calculation are successively taken in this program to gain the steady-state for a multiphase pipe network. For the hydraulic equilibrium calculation, applying flow equation to each pipe in the network gains a pipe flow vector. A nonlinear system of equations, which represent flow balance of each node, is obtained by multiplying the incidence matrix and the pipe flow vector. To solve these equations, the Newton-Raphson iterative algorithm is used and afterwards, the hydraulic parameters of the pipe network are obtained. For thermal equilibrium calculation, since all the temperature of source nodes is known, the key step is to find the solution order of other node temperature. The program obtains the order by transforming the adjacency matrix. Deng temperature drop formula is used to calculate the end temperature of each pipe. When a node has more than one inflow, an average temperature based on the heat capacity and mass flow is adopted after gaining each pipe’s outlet temperature. Combining hydraulic and thermal algorithms, a complete set of solution program for steady-state of multiphase pipe network is compiled. In the end, two cases are performed to check the accuracy of the program. In the first case, a pipe network is created by using the data collected from a condensate gas gathering network in the South China Sea. The result indicates that the program has a good agreement with the actual data. In the second case, the program is applied in a single-phase network and gains almost the same result calculated by PipePhase and PipeSim.

When operating a compressor station, given its mass flow rate, inlet pressure and temperature, and discharge pressure, dispatchers need to decide which compressors to run and at what flow rates, i.e., the operating scheme of the station, to cut its energy costs. This paper addresses this problem under unsteady states. This means that at least one of the four given operating parameters is time-dependent, and therefore so is the operating scheme. The key constraints of the problem are the minimum uptime and downtime of each compressor, which interconnect the operating schemes at each time step and complicate the problem. The energy cost of a compressor unit is almost a linear function of its flow rate for a given inlet pressure, inlet temperature, and discharge pressure. Therefore, the optimization problem was formulated as a mixed integer linear programming (MILP) model, which was solved by CPLEX. The optimal operating schemes given by CPLEX were simulated to reevaluate the objective function, and the error of the linearized energy cost model was shown to be within 5%. The recalculated objective function values were 0.22%–1.18% higher than those of the true optimum. However, the MILP method was 0.49–64.95 times faster than the dynamic programming approach yielding global optimal solutions.

Gas pipelines are often operated in transient states because of time-varying consumer demands for natural gas. For a certain operating period of a gas pipeline, given the delivery rates at the pipeline's delivery points and the flow rates or pressures of its gas sources as functions of time, pipeline dispatchers face a transient optimization problem with the objective of minimizing pipeline fuel consumption for the period. To address this problem, a two-level model is constructed. The model includes a pipeline level that optimizes the discharge pressure of each compressor station and a station level that optimizes the operating scheme of each compressor station. A key assumption, that the discharge pressures of each compressor station on the pipeline are time-independent, is made to simplify the problem. Based on this assumption, a dynamic programming (DP)-based algorithm is proposed for the pipeline level in which the discharge pressures are chosen as the state variables. The algorithm is essentially a recursion from the pipeline destination to the origin. The i -th stage of the recursion covers the i -th and the ( i + 1)-th compressor stations together with the pipeline segment between them, and the state transition of the stage reflects the relationship between the discharge pressures of the two compressor stations. Unlike in steady-state operation, determining this relationship involves the partial differential equations governing transient gas flow in the pipeline segment between two adjacent stations. Because these equations must be solved by numerical simulation, it is much more difficult to determine the relationship for transient operation than for steady-state operation. To compress the gas going through a compressor station to a compression ratio assigned at the pipeline level, the operating scheme of the station is solved at the station level. A preprocessing method is devised to reduce the computational time of the DP approach. The method approximates the transient optimization problem as a series of steady-state optimization problems. The results provide information that can narrow the discharge pressure region of each compressor station. A simple example shows that the approximate minimum fuel consumption given by the proposed algorithm is 6.2% higher than the true optimum. Typical cases for different operating periods are tested on a gas pipeline. The proposed approach is also tested on a network studied in the literature. For most of the case studies, optimal solutions can be computed by the proposed approach within 15 min. In addition, the computational complexity grows modestly as the period becomes longer.

In recent years, the variable speed pumps (VSP) are widely used in all walks of life. With respect to the oil & gas industry, they are one of the most important equipment in the long distance pipelines. To prevent the phenomenon of throttling, which would cause unnecessary energy waste, the variable drives are utilised connected to the axes of the pumps.