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At present, steam-assisted gravity drainage technology has failed to meet the requirement for the large-scale development of abundant oil sands resources due to high production cost and serious environmental pollution caused by huge amounts of carbon emissions. Therefore, this paper proposes a radio frequency technology for heating oil sands and establishes a corresponding mathematical model that considers the phase transition of water. Then, a lab-scale experimental setup is designed to experimentally investigate the performance of radio frequency heating based on the phase change. Finally, the influences of phase transition of water on the temperature distribution of oil sand samples are analyzed in detail. The results show that the mathematical model of radio frequency heating can accurately predict the temperature distribution prior to the phase transition of water due to the little effect of phase transition on the thermal properties and density of oil sand samples. The failure to consider the effect of phase transition of water on electrical conductivity of oil sand in the mathematical model accounts for a large deviation between the measured temperature data and numerical results. So, in order to make the calculated temperature results more accurate, this effect should be considered during numerical simulation.

This article discusses the problem of how to efficiently build aircraft routes that better withstand potential disruptions, such as bad weather, technical problems, and passenger delays. This optimization problem is called robust aircraft maintenance routing problem (RAMRP). There are three approaches in the literature to deal with the RAMRP, such as the buffer time allocation approach (BT), the departure retiming approach (DR), and the scenario-based stochastic programming approach (SSP). Most of the previous approaches have some shortcomings in terms of fleet productivity and delay absorption. In addition, the majority of the RAMRP models overlook maintenance regulations, which result in the generation of infeasible routes. In this article, RAMRP is investigated with two main objectives. First, a novel robustness approach, called the turn-around time reduction approach (TRTR), that avoids the shortcomings of the existing approaches, is incorporated into RAMRP. The second objective is to develop an RAMRP model that simultaneously considers all maintenance regulations. The effectiveness of the proposed RAMRP model along with the TRTR is demonstrated using real data from a major Middle Eastern airline. The results reveal an improved performance of the TRTR over the BT by about 3.43%–12.20% and 2.5%–13.58%, while handling the expected propagated delay costs and fleet productivity, respectively. In addition, the results show that the TRTR is better than the SSP by about 2.07%–18.82%, while minimizing the propagated delay costs. Therefore, the TRTR has a great potential to be implemented in the actual industry.

PurposeBased on structural embeddedness theory and resource dependence theory, this research aims to examine the mediation role of information sharing in the relationship between deendency structures and electronic supply chain management system (eSCM) adoption and a firm's intention to adopt eSCMs.Design/methodology/approachA survey questionnaire was undertaken from 212 companies based in Mainland China. Three-stage least squares (3SLS) regression was employed to test the research model.FindingsThe results from 3SLS regressions showed that the effect of interdependence on eSCM adoption intention is fully mediated through information sharing when relationship duration is either below or about the mean. Interdependence and dependence disadvantage was shown to have significant positive effects on eSCM adoption while the effect of dependence advantage was statistically insignificant. Relationship duration was found to negatively moderate the relationship between information sharing and adoption intention.Originality/valueThrough investigating factors of inter-organizational relationships, this study fills the knowledge gap in the traditional paradigms which ignore the collaborative nature of eSCM and analyse related problems based on a single firm's point of view.

The performance and learning speed of the Cascade Correlation neural network (CasCor) may not be optimal because of redundant hidden units’ in the cascade architecture and the tuning of connection ...

With the development of sensing and communications technology, some new features have emerged in manufacturing processes, such as highly correlated, deeply integrated, dynamically integrated, and a...

Uncertainty and risk are inevitable issues in decision making in supply chain systems. In knowledge-based communities, uncertain conditions are recognized, analyzed and eliminated using wide range of concepts and approaches. One intelligent tool to aid in decreasing impreciseness and in delivering an acceptable level of accuracy is fuzzy logic. This study reports a new version of the fuzzy multiple criteria decision-making family. The decision-making trial and evaluation laboratory (DEMATEL) is extended for the first time with interval fuzzy values and then integrated as an input for the quality function deployment (QFD) mechanism. Although the application of decision-making tools in the supply chain and its sustainable development is undeniable, the implementation of fuzzy decision support systems in sustainable supply chains still demands more research work. This study develops an IT2F DEMATEL-QFD model to evaluate and rank sustainable supply chain drivers in a group decision-making environment. The proposed fuzzy decision model is connected to a real research project for eliminating risks in the supply chain related to agricultural production systems. Sensitivity analysis confirms the stability of the model. It is concluded that the outcomes and advantages of the newly developed model will profit academic and non-academic partners.

Sustainable and efficient food supply chain has become an essential component of one’s life. The model proposed in this paper is deeply linked to people's quality of life as a result of which there...

This paper proposes a multi-objective integrated container terminal scheduling problem considering three key components: berth allocation, quay cranes assignment and containers transportation in port operation process. In the suggested problem, one of the objectives is to shorten service time of ships with by coordinating of quay cranes, and the other is to reduce operating costs of quay cranes and yard trucks. Then, a Multi-objective Bacterial Colony Optimization algorithm (MOBCO) incorporating concepts of multi-swarm, topology, personal best and global best, named Multi-objective BCO with ring topology (MORBCO), is designed to handle the resulting problem. The extension of standard MOBCO to the MORBCO involves the addition of three specialized strategies: global chemotaxis operation, elite reproduction strategy and personal best archive with neighborhood communication mechanism. In order to test the performance of the MORBCO, benchmark tests are performed and compared with traditional MOBCO and three other well-known multi-objective algorithms first. The computational results indicate that the proposed algorithm can outperform other rivals and efficiently solve a variety of multi-objective problems in most of cases. Subsequently, MORBCO and two best performing algorithms from the previous test are applied to three instances generated by the proposed model. Judging by quality and diversity of obtained non-dominant solutions, we find that MORBCO has superior performance, especially for large instances of the container terminal problem.

Supply chain finance (SCF) aims to improve the overall creditability of the entire supply chain, including buyers, suppliers, and financial service providers, through an inter-organizational approach. In SCF, companies will collaborate with each other to maximise the mutual benefits. Companies, such as those involving suppliers, may sell their invoices to banks or any other financial service provider at a discount in order to cash in the invoices immediately for achieving better cash flow. Accordingly, the role of financial service providers becomes the most critical because they control the discount rates offered, while bearing all the risks, which is why they are also known as the risk takers. In existing literature and in practice, the discount rate is usually determined by the relationship between buyers and financial service providers. Therefore, it is necessary to understand what factors are considered during decision-making and whether the traditional collaborative factors considered in the literature on supply chain collaboration are still valid. So far, the supply chain collaborative factors have not been studied scientifically from the point of view of financial service providers. Therefore, in this work, we investigated how important these factors are for financial service providers. We identified the most important factors from the literature on supply chain collaboration and conducted interviews with many experienced practitioners in financial service industries in China. We employed interpretive structural modelling to model the relationship between collaborative factors and understand the importance of each factor. The results revealed that top management support, trust, and IT infrastructure are the factors considered the most important by financial service providers. Interestingly, we also found that incentives are the least important factors in SCF.

Social capital is generally believed to facilitate protest mobilization. We examine, however, whether and how it might reduce an individual’s tendency to join a protest. Analyzing survey data of a migrant population in Beijing, China’s capital, we find that social capital operating as better embeddedness in local social networks lowers the likelihood of protest participation. We reason that, structurally, embeddedness in local networks provides access to support and assistance, reducing the attractiveness of disruptive means of problem-solving. Psychologically, such embeddedness mitigates the feeling of relative deprivation, reducing the possibility of such feelings accumulating and eventually translating into protesting actions. Regressions and structural equation models confirm our hypotheses, and we are also able to check the robustness of our findings with a different, much larger, cross-national dataset.

Clusters in a precursor solution play an important role in metal oxide semiconductor films. Additives including acetic acid (AcOH) and acetylacetone (acac) were applied in a precursor solution to a...

In this article, we performed gated four-probe measurements on amorphous indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs) to extract their intrinsic mobility and contact resistance as functions of gate voltage and temperature. The abnormal degradation of field-effect mobility was observed in a-IGZO TFTs both at high gate voltage and at high temperature. Results showed that contact resistance played a major role in mobility degradation at high gate bias, whereas band-like transport (phonon scattering) accounts for mobility degeneration at high temperature. We proposed a novel method, which exposed the contact regions to ultraviolet (UV) ozone. The mobility was boosted from 23 to 30 cm2/Vs, nearly 40% increment at high gate bias.

The Internet has played important roles in driving political changes around the world. Why does it help to topple political regimes in some places but improve the quality of governance in others? We found Internet usage in general leads to citizens’ distrust in political institutions. Different political environments, however, can condition such trust-eroding impacts of the Internet in significantly different ways. A democracy enables citizens to connect their online behaviors and offline expression and organization, releasing political discontent while facilitating state–society communication. On the contrary, by restricting various forms of off-line expression, authoritarian regimes drive Internet-active citizens' discontent and distrust to higher levels. We use the World Values Survey data to establish these different mechanisms across democracies and authoritarian systems. Entropy balancing shows our findings to be highly robust.

Purpose The purpose of this paper is to develop a model which schedules activities and allocates resources in a resource constrained project management problem. This paper also considers learning rate and uncertainties in the activity durations. Design/methodology/approach An activity schedule with requirements of different resource units is used to calculate the objectives: makespan and resource efficiency. A comparisons between non-dominated sorting genetic algorithm – II (NSGA-II) and non-dominated sorting genetic algorithm – III (NSGA-III) is done to calculate near optimal solutions. Buffers are introduced in the activity schedule to take uncertainty into account and learning rate is used to incorporate the learning effect. Findings The results show that NSGA-III gives better near optimal solutions than NSGA-II for multi-objective problem with different complexities of activity schedule. Research limitations/implications The paper does not considers activity sequencing with multiple activity relations (for instance partial overlapping among different activities) and dynamic events occurring in between or during activities. Practical implications The paper helps project managers in manufacturing industry to schedule the activities and allocate resources for a near-real world environment. Originality/value This paper takes into account both the learning rate and the uncertainties in the activity duration for a resource constrained project management problem. The uncertainty in both the individual durations of activities and the whole project duration time is taken into consideration. Genetic algorithms were used to solve the problem at hand.

Wide-body aircraft are frequently used to meet upsurges in passenger demand, resulting in the underutilization of the belly-hold capacity on many routes. In the existing literature, investigating this specific underutilization problem has not received much attention from scholars in this field. Therefore, in this paper, we study this problem with two main objectives. First, to propose an Extra-baggage service as a solution to the underutilization problem. Second, to provide the associated prices for the proposed extra-baggage service. For this purpose, we adopt the newsvendor-based pricing model that explores different prices, while combining different amounts of extra-baggage and cargo in the belly-hold space. To demonstrate the potential and feasibility of the proposed service, a numerical simulation has been performed. The simulation includes comparing the expected profit from cargo allocation with the expected profit from the allocation of a combination cargo with Extra-baggage. The simulation results show a significant profit improvement for the airlines, while using the Extra-baggage scheme. This is apparent as the profit increases by 25% over the current excess baggage scheme. Moreover, the results show a double profit improvement in various seasons. This performance echoes the importance of the extra-baggage service being implemented in real practice.

Purpose The purpose of this paper is to study the impacts of time segment modeling approach for berth allocation and quay crane (QC) assignment on container terminal operations efficiency. Design/methodology/approach The authors model the small time segment modeling approach, based on minutes, which can be a minute, 15 min, etc. Moreover, the authors divided the problem into three sub-problems and proposed a novel three-level genetic algorithm (3LGA) with QC shifting heuristics to deal with the problem. The objective function here is to minimize the total service time by using different time segments for comparison and analysis. Findings First, the study shows that by reducing the time segment, the complexity of the problem increases dramatically. Traditional meta-heuristic, such as genetic algorithm, simulated annealing, etc., becomes not very promising. Second, the proposed 3LGA with QC shifting heuristics outperforms the traditional ones. In addition, by using a smaller time segment, the idling time of berth and QC can be reduced significantly. This greatly benefits the container terminal operations efficiency, and customer service level. Practical implications Nowadays, transshipment becomes the main business to many container terminals, especially in Southeast Asia (e.g. Hong Kong and Singapore). In these terminals, vessel arrivals are usually very frequent with small handling volume and very short staying time, e.g. 1.5 h. Therefore, a traditional hourly based modeling approach may cause significant berth and QC idling, and consequently cannot meet their practical needs. In this connection, a small time segment modeling approach is requested by industrial practitioners. Originality/value In the existing literature, berth allocation and QC assignment are usually in an hourly based approach. However, such modeling induces much idling time and consequently causes low utilization and poor service quality level. Therefore, a novel small time segment modeling approach is proposed with a novel optimization algorithm.

Summary To increase the commercial prospects of metal halide perovskite solar cells, there is a need for simple, cost-effective, and generalized approaches that mitigate their intrinsic thermal instability. Here we show that 1,3,7-trimethylxanthine, a commodity chemical with two conjugated carboxyl groups better known by its common name caffeine, improves the performance and thermal stability of perovskite solar cells based on both MAPbI3 and CsFAMAPbI3 active layers. The strong interaction between caffeine and Pb2+ ions serves as a “molecular lock” that increases the activation energy during film crystallization, delivering a perovskite film with preferred orientation, improved electronic properties, reduced ion migration, and greatly enhanced thermal stability. Planar n-i-p solar cells based on caffeine-incorporated pure MAPbI3 perovskites, which are notoriously unstable, exhibit a champion-stabilized efficiency of 19.8% and retain over 85% of their efficiency under continuous annealing at 85°C in nitrogen.

In the situation of continuous low oil price worldwide, the conventional thermal recovery technologies have gradually exposed the defect of low profit. Therefore, there have been increasing research interests focused on the electromagnetic (EM) heating method for enhanced heavy oil recovery. This paper proposes an application of waveguide to transmit high-frequency EM waves from the surface into the underground for heating the target area; besides, the factors affecting the EM heating effect are analyzed. Originally, a three-dimensional simplified model composed of reservoir, rectangular waveguide and resonant cavity is established. Then, the governing equations of EM field and temperature field are coupled to quantitatively describe the heating process, and at length, the effects of the operating parameters of EM heating and of the reservoir properties on temperature distribution are investigated. Simulation results are validated by the actual data obtained from laboratory experiment. For the constant reservoir properties, the increase in EM power can significantly raise the reservoir temperature and expand heating area. Although the higher EM frequency sharply heightens the reservoir temperature, the heat only penetrates limited distance. Reservoir temperature ascends as the rise of the conductivity, porosity and water saturation of the reservoir. In addition, the relative permittivity of water is a vital physical parameter during the EM heating process. Those results can provide guidance for the field-scale implementation of EM heating technology.

The sustained casing pressure (SCP) problems in shale gas wells have not been effectively controlled by now. In field, the expandable cement sheath used in wells has decreased the SCP problems and in this paper, an analytical model is established to study how the expandable cement increases the sealing ability of cement sheath and give suggestions on optimized choosing of expandable cement. Meanwhile, the stress equilibrium state in well before cementing work which has not been considered in previous and it is considered in the analytical model here. During the curing process, the radial stress on the outer interface of cement sheath changes with time and increases much faster than it on the inner interface. In wells with single layer of casing, the radial stress on interfaces does not increase linearly with the cement elastic modulus (Et) and it will be affected by the elastic modulus of formation rock. In wells with double layers of casing, the expandable cement can significantly increase radial stress on interfaces during the production process and alters circumferential tensile stress into compressive stress which is useful for increasing the sealing ability of cement sheath. How the expandable cement increase the sealing ability of cement sheath in field has been analyzed and an optimized expand ratio of cement is proposed to control the SCP problems in shale gas wells.

An aircraft hangar maintenance scheduling problem is studied, motivated by the aircraft heavy maintenance conducted in a hangar operated by an independent maintenance service company. The aircraft hangar maintenance scheduling problem in such context consists of determining a maintenance schedule with minimum penalty costs in fulfilling maintenance requests, and a series of hangar parking plans aligned with the maintenance schedule through the planning period. A mixed-integer linear programming (MILP) mathematical model, integrating the interrelations between the maintenance schedule and aircraft parking layout plans, is presented at first. In the model, the variation of parking capacity of the maintenance hangar and the blocking of the aircraft rolling in and out path are considered. Secondly, the model is enhanced by narrowing down the domain of the time-related decision variables to the possible rolling in and out operations time of each maintenance request. Thirdly, to obtain good quality feasible solutions for large scale instances, a rolling horizon approach incorporating the enhanced mathematical model is presented. The results of computational experiments are reported, showing: (i) the effectiveness of the event-based discrete time MILP model and (ii) the scalability of the rolling horizon approach that is able to provide good feasible solutions for large size instances covering a long planning period.

This study develops a Stackelberg-Nash game model (SNGM) to capture the interdependence between aircraft routing of airlines and maintenance staffing of maintenance providers, and to consider the price competition among maintenance providers. The SNGM’s overall Nash equilibrium is obtained using an iterative game algorithm. The SNGM effectiveness is demonstrated with a case study, in which a neural network-based algorithm is developed to forecast accurate non-propagated delays, and a multiple linear regression algorithm is adopted to predict demand-price relationship for each maintenance provider. The results reveal cost savings of about 26% and 22% for the airline and the maintenance providers, respectively.

The world is now considered as a small village, and with increasing commercial and cultural adverse between nations, air transport continues to boom and passenger numbers are continuously increasing. This increase leads to extensive use of wide-bodied aircraft which have large space in the aircraft belly-hold resulting in cargo sector having overcapacity. In this regard, the belly-hold overcapacity is discussed with two objectives to fill the unused spaces. Firstly, designing the extra-baggage service. Secondly, conferring price setting for the new service with reference to the cargo price. We adopt the multi-item newsvendor based pricing model to derive a price formula for the extra-baggage service as a function of cargo price. The stochastic extra-baggage and deterministic cargo demands were firstly modeled. The results showed that the optimal extra-baggage price can be determined as a function of cargo price in terms of the base price plus a premium price, but it gave an exaggerated extra-baggage price. Therefore, we modeled the cargo demand in stochastic form, and the second model showed better results because it cancels the effect of cargo penalties in deterministic cargo demand. Moreover, the stochastic cargo model gives the airline the opportunity to switch between two different pricing strategies either market penetration or pure premium strategy. Finally, the model can be generalized for any two products that share common features and serve in the same market.

The flight delay-based operational aircraft maintenance routing problem (OAMRPFD) and the maintenance staffing problem (MSP) are interrelated and interdependent. Despite this interdependency, each problem is solved separately. Therefore, the optimal plan specified by each problem is not executed as planned, which consequently increases the operating cost of each aspect of the problem. The present research paper studies OAMRPFD in addition to MSP, with two main objectives. The first is to develop an OAMRPFD model that appropriately reflects the flight delay and, accordingly, a new stochastic framework of a scenario-based OAMRPFD (SOAMRPFD) is put forward. The second is to handle the interdependence between SOAMRPFD and MSP, by proposing a coordinated configuration of SOAMRPFD and MSP that is formulated like the leader–follower Stackelberg game, with SOAMRPFD as the leader and MSP as the follower. A bi-level optimization model is used to present this game and is solved by a bi-level nested ant colony optimization (ACO) algorithm. The viability and potential of the proposed model are established using a major airline and a maintenance company, which are based in the Middle East, as a case study. The results demonstrate significant cost savings for both the airline and maintenance company.

Technology of downhole data transmission based on drilling fluid continuous pressure waves is extensively applied to the drilling operation of oil/gas wells due to high transmission rate. For generation of the continuous pressure waves, this paper designs a signal generator with multi-row valve ports, and an optimization model is established to preliminarily solve the valve ports distribution. In addition, a laboratory experiment is carried out to determine the relationship between flow and pressure of the drilling fluid flowing through the multi-row valve ports, and the flow coefficient and valve port exponent herein are adopted to modify the previous optimization result of the valve ports distribution. Ultimately, the pressure waves produced by the preliminary and modified optimization results are compared with sine wave. Results show that the multi-row valve port exponent and flow coefficient are experimentally measured to be 0.3 and 0.75, respectively, and based on them, the modified optimization result of the valve ports distribution is capable of generating a pressure wave that has a higher similarity with sine wave. This is because that the correlation coefficient between them is as high as 0.9978, which is very close to 1. Research results indicate the optimization model for calculating the valve ports distribution is correct. Furthermore, the experimental data are reliable and can accurately reveal the flow and pressure characteristics of the multi-row valve ports.

In this paper, the reasons for cracking in the longitudinal and spiral of Q125 casing in ultra-deep wells (UDWs) at the Tarim Oilfield were investigated for the first time ever. Up to know an evaluation of Q125 casing materials of UDWs were were limited to comparisons with WSP-2T and P110 via performance tests. In addition, an applicability evaluation of UDWs was carried out using MPC software and theoretical calculations. The results show that mechanical damage and stress corrosion cracking are the principal causes for longitudinal cracking. Spiral cracking can be the result of the manufacturing process. It should be added that the material out of which Q125 casing is produced manifests high strength, low toughness and great sensitivity to cracks, stress corrosion and low allowable limit crack size (ALCS) when compared with WSP-2T and P110. Owing to the complicated field environment of UDWs at the Tarim Oilfield, the causes of cracking failure have been analyzed, with the result that WSP-2T casing of a similar strength to Q125 casing ought to be selected in UDWs rather than Q125 casing with high strength and low toughness, which is significant for the development of UDWs at the Tarim Oilfield.

Purpose In seaport industries, vessel arrival delay is inevitable because of numerous factors, e.g. weather, delay due to the previous stop, etc. The period of delay can be as short at 15 min of as long as a few days. This causes disruption to the planned sea operation operations, and more importantly, to the resources utilization. In traditional berth allocation and quay crane assignment problems (BA-QCA), the risk of vessel arrival delay has not been considered. Accordingly, the purpose of this paper is to employ a proactive planning approach by taking into consideration the vessel arrival delay into the optimization of BA-QCA problems. Design/methodology/approach In the existing BA-QCA problems, vessel arrival time is usually deterministic. In order to capture the uncertainties of arrival delay, this paper models the arrival time as a probability distribution function. Moreover, this paper proposes to model the delay risk by using the period between the expected arrival time and the expected waiting time of a vessel. Lastly, the authors propose a new modified genetic algorithm and a new quay crane assignment heuristic to maximize the schedule reliability of BA-QCA. Findings A number of numerical experiments are conducted. First of all, the optimization quality of the proposed algorithm is compared with the traditional genetic algorithm for verifying the correctness of the optimization approach. Then, the impact of vessel arrival delay is tested in different scenarios. The results demonstrate that the impact of vessel arrival delay can be minimized, especially in the situations of high vessel to potential berth ratio. Research limitations/implications The proposed vessel arrival modeling approach and the BA and QCA approach can increase the operations efficiency of seaports. These approaches can increase the resource utilization by reducing the effect of vessel arrival delay. In other words, this can improve the throughput of seaport terminals. Originality/value This paper proposes to minimize the delay risk based on the conditional probability of the vessel completion time based on the previous vessel at the assigned berth. This modeling approach is new in literature.

This paper examines how open e-logistic standards (OELS) affect firm performance through developing supply chain ambidexterity. We conceptualize supply chain process ambidexterity as the ability of...

At present, a technology of RF (radio frequency) heating is being investigated for enhanced heavy oil recovery, but continued high temperature appears near wellbore, which may destroy the wellbore integrity and RF apparatus. This paper first introduces a novel RF apparatus composed of antenna arrays for heating the heavy oil reservoir, and then the temperature distribution is calculated based on the coupling between electromagnetic and temperature field. To alleviate the high temperature in the vicinity of wellbore, two solutions are proposed: (1) a sleeve made of PTFE (polytetrafluoroethylene) is applied to the outside of the RF apparatus; (2) for improving accuracy of temperature calculation, thermos-physical parameters of reservoir, which are depended on the temperature, are considered specifically in the heat transfer equation and wave equation. Finally, the effect of properties of reservoir and the relative permittivity of sleeve on temperature distribution are investigated. Calculation results indicate that relative permittivity of sleeve has a tremendous influence on temperature distribution, and maximum temperature declines nearby the wellbore as the diminution of relative permittivity, moreover, the positions with highest temperature are moving far from the wellbore. When the parameters of specific heat and thermal conductivity are variable, the maximum temperature near the wellbore is lower than the temperature calculated by constant parameters. Variable relative permittivity of water can’t decrease the temperature around the wellbore.

One important way to understand political change in China is to examine how citizens participate in and interact with China’s grassroots system of governance. Urban grassroots self-governance is organized around the residents committees (RCs) of various urban neighborhoods. While earlier research tends to characterize the RC as an institution for government control and penetration of society, the active and largely voluntary participation found in this study challenges this state-dominant view. Based on survey data collected in six provinces in China, we discovered a wide range of participatory activities by residents in local self-governance processes. Institutions and activities of such “democratic localism” give rise to thick networks and interactions among fellow residents and between them and higher levels of governance. Our “Democratic Localism” framework urges researchers to resist focusing solely on the changes at the highest system-level (i.e., the eventual democratization of the Chinese state), but instead to pay more attention to politics and governance as played out in the local affairs of community residents. We find that satisfactory democratic governance relies heavily on inclusiveness and competition in the various institutional spheres, and participation in local politics casts heavy influence on citizens’ perception of national-level politics.

Casing wear has become an increasingly urgent research topic alongside advancements in extended-reach drilling (ERD) engineering. The drill string in an ERD operation is likely to undergo whirling motion, which is known to impact casing wear prediction accuracy; there have not yet been long-term studies on the related mechanisms, however. In this study, we develop a new prediction model called circumferential casing wear model (CCWD) based on the energy principle and the geometric properties, which accounts for the effects of drill string whirling motion on casing wear. Besides, composite casing wear models considering with the CCWD and casing wear groove model (CWGD) are also discussed. The results via case study to find that the proposed CCWD model of whirling motion can contribute to the accuracy of casing wear prediction. If the whirling motion is ignored, a large prediction error could occurred when only CWGD model is used. In the sensitivity analysis, the worn casing depth may increase alongside increases in whirling motion angular velocity, rotary table angular velocity, sliding and rolling friction coefficient, outer tool joint radius, and drill string weight. Slight variations in whirling motion angular velocity and rolling friction coefficient can cause substantial casing wear. Thus whirling motion must be strictly controlled during the drilling process to prevent engineering failure. To this effect, the model presented in this paper has both theoretical and practical applications for enhancing the accuracy of casing wear prediction to develop oil and gas reservoirs in ERD.

At present, radio frequency heating is regarded as a novel approach for crude oil extraction from heavy oil reservoir. But in the absence of any external assistance, it is difficult to further improve its heating performance, especially for the reservoirs with poor thermal conductivity and low electrical conductivity. Therefore, to solve the problem, this paper proposes a hybrid technique that combines the radio frequency heating and injection of conductive medium into hydraulic fractures. A mathematical model is firstly established to describe the radio frequency heating process, and then the model is verified by the temperature data obtained from laboratory experiment. Finally, the effects of the conductive medium properties, fracture position and width on reservoir temperature distribution are analyzed. Simulation results indicate that the specific heat, thermal conductivity and density of conductive medium have no obvious effect on reservoir temperature distribution, but the electrical conductivity within the range of 10–30 S/m can apparently cause temperature variation. Additionally, the influence of fracture position on temperature distribution is tremendous, but the fracture width fails to impact the temperature distribution due to small width ranges. This investigation provides a better solution for radio frequency heating to obtain greater heat extraction performance.

In research on China’s state-controlled elections, whether pro-democratic and politically efficacious citizens vote or abstain more has dominated the debate. Analyzing an up-to-date data set, we find class status and citizens’ institutional environment command overwhelming power in determining voter turnout, while psychological and motivational variables show no significant impacts. Specifically, members of the middle class employed in the state sector are more likely to vote than other social groups, while their counterparts in the private and foreign sectors are far less inclined to vote. While in general, citizens show relatively high level of support for the regime, except among the state-employed middle class, this support is not translated into a higher turnout rate. Electoral behaviors of Chinese citizens, therefore, are heavily conditioned by an individual social group’s particular relation with the state. Members of the Communist Party turn out to vote no more than other members of the society, revealing a critical institutional failure the system faces.

Compared with other electrical heating processes, RF heating has the advantages of volumetric heating, therefore it has great development potential in extracting heavy oil resources. Because the EM waves used to heat reservoir are mainly derived from RF antennas, it is necessary to determine the multi-antennas layout in the horizontal wellbore to maximize the thermal energy dissipation in a single reservoir layer with uneven thickness, and minimize the extra heat loss in non-reservoir. In this work, the combination of three antenna arrays is considered during RF heating process, and the effects of their distance and operating parameters (voltage, and frequency) on heating patterns are analyzed. In addition, in order to achieve the purpose of heating reservoir at the expense of the least amount of electrical energy, the heating efficiencies of the antenna arrays with equal and different spacing are compared. At last the mathematical model used to describe RF heating process is solved by COMSOL to obtain the reservoir temperature profiles. Simulation results indicates that the frequency and voltage applied to each dipole antenna have a contribution to the heating pattern, including heating range and direction. With the increasing antenna array spacing, the heating range expands, but the maximum reservoir temperature declines. In addition, the temperature distributions in the perpendicular bisectors of any two adjacent antennas trend to gradually diminish with the increasing spacing. Gradually increasing antenna spacing will also weaken the temperature accumulation effect at the center of the reservoir. When the single reservoir layer with different thicknesses is heated, the maximum heating efficiency is 0.73 in the condition of the antenna configuration with the same spacing. Whereas, the efficiency is up to 0.88 if the optimized spacing is adopted. Results indicate that the heating mode can be governed by optimizing the heating distance, as well as selecting the appropriate operating parameters. The determination of RF heating pattern can provide the solutions for the placement of multiple antennas in horizontal boreholes. Ultimately, the extra energy waste is avoided and the maximum heating efficiency is accomplished.