Search Results (399)

This essay argues for the reciprocal benefits of joining the new theories of matter emerging out of critical posthumanism and the psychedelic drugs currently experiencing a so-called “renaissance” in global north societies. While the former’s twin emphasis on relationality and embodiment is perfectly suited to capture and ground the ontological, epistemological, and ethical implications of psychedelic experiences of interconnectedness and transformation, these substances are in turn powerful companions through which to enact a “posthuman phenomenology” that helps us with the urgent task to “access, amplify, and describe” our deep imbrication with our more-than-human environments. In other words, I argue that while the “new materialism” emerging out of posthumanism can help elaborate a psychedelic rationality, psychedelics can in turn operate as educators in materiality. It is from this materialist perspective that we can best make sense of psychedelics’ often touted potential for social transformation and the enduring suspicion that they are somehow at odds with the “ontoepistemological order” of modernity. From this point of view, I contend that a crucial critical move is to push against the common trope that this opposition is best expressed as a turn from the narrow scientific and “consumerist materialism” of modern Western societies to more expansive “spiritual” worldviews. Pushing against this science-–spirituality binary, which in fact reproduces modern “indivi/dualism” by confining psychedelic experience inside our heads, I argue instead that what is in fact needed to think through and actualize such potentials is an increased attention to our material transcorporeality. In a nutshell, if we want psychedelics to inform social change, we must be more, not less, materialist—albeit by redefining matter in a rather “weird”, non-reductive way and by redefining consciousness as embodied. By the end of the essay, attaching psychedelics to a new materialism will enable us to formulate a “material spirituality” that establishes psychedelics’ political value less in an idealistic or cognitive “politics of consciousness” and more in a “materialization of critique”. Full article

Differential privacy is a robust framework for private data analysis and query processing, which achieves privacy preservation by introducing controlled noise to query results in a centralized setting. The sensitivity of a query, defined as the maximum change in query output resulting from the addition or removal of a single data record, directly influences the magnitude of noise to be introduced. Computing sensitivity for simple queries, such as count queries, is straightforward, but it becomes significantly more challenging for complex queries involving join operations. In such cases, the global sensitivity can be unbounded, which substantially impacts the accuracy of query results. While existing measures like elastic sensitivity and residual sensitivity provide upper bounds on local sensitivity to reduce noise, they often struggle with either low utility or high computational overhead when applied to complex join queries. In this paper, we propose two novel sensitivity estimation methods based on sampling and sketching techniques, which provide competitive utility while achieving higher efficiency compared to existing state-of-the-art approaches. Experiments on real-world and benchmark datasets confirm that both methods enable efficient differentially private joins, significantly enhancing the usability of online interactive query systems. Full article

This paper suggests an extensive inferential method for the Power Pratibha Distribution (PPD) under Unified Hybrid Censoring Schemes (UHCSs), since there is a growing interest in flexible models in both reliability and service operations. This work studies the PPD model using standard Maximum Likelihood Estimation methods and modern Bayesian approaches too. Using a complex architecture, UHCS simulates tests more closely to what is done in practice than by using more basic censoring schemes. Using analysis, the probability and statistical ranges are carefully calculated for the parameters. Tests demonstrate that Bayesian estimation gives better results than many other methods for estimation, especially when the dataset is not very large and when a lot of data is missing. Real-world tests of electromigration failure data and banking service times help to test the methods. In both situations, the PPD shows it can be used successfully in different reliability settings. By joining advanced censoring models and reliable statistical methods, this research gives a helpful toolset to experts in reliability analysis and statistics. Full article

As the Internet of Things (IoT) continues to evolve, the demand for cross-domain collaboration between devices and data sharing has grown significantly. Operations confined to a single trust domain can no longer satisfy this requirement, so cross-domain access to resources is becoming an inevitable trend in the evolution of the IIoT. Due to identity trust issues between different domains, authorized access is required before resources can be shared. However, most existing cross-domain authentication schemes face significant challenges in terms of dynamic membership management, privacy protection, and traceability. These schemes involve complex and inefficient interactions and fail to meet the dynamic and lightweight requirements of the IIoT. To address these issues, we propose a privacy-preserving and traceable cross-domain authentication scheme based on dynamic group signatures that enables efficient authentication. The scheme supports anonymous authentication via succinct proofs and incorporates a trapdoor mechanism to enable group managers to trace and revoke malicious identities. Additionally, our solution supports efficient joining and revoking of members and implements blacklist-based proof of non-membership. We formally prove the security of the proposed scheme. The experimental results demonstrate that the proposed scheme outperforms others in terms of computational cost and revocation overhead. Full article

In intermittent gas lift (IGL), not all the liquid initially in the tubing is usually produced at the surface in one cycle. This is due to a concept known as fallback, which occurs when some amount of the initial liquid column drops back to join the next slug. We conducted a review of earlier works on IGL and the behavior of the fallback factor. The dependence on the fallback factor on the operational conditions such as slug velocity, valve opening pressure, valve closing pressure, casing–tubing pressure ratio, diameter of tubing, and amount of gas injected during IGL are discussed in this paper. The effect on the shape and stability of the nose of the Taylor bubble on the lifting efficiency of the bubble is also explained. In trying to reduce the fallback factor per cycle, there have been recommendations to combine gas lift with plunger lift. We also present the results of this combination and the effects on the fallback factor in gas-assisted plunger lift (GAPL). More light is shed on the behavior of the velocity of the liquid slug and how it affects the fallback factor during IGL. The behavior of the fallback factor with an increase or decrease in plunger velocity during GAPL is also presented in this paper. This review is categorized into experimental and numerical studies on fallback factor to evaluate their impact on production efficiency in IGL and GAPL. Additionally, different formulas for fallback proposed by different literature are compiled. Full article

Composite materials’ contribution to the construction of manned and unmanned aircraft continues to grow and, together with the increased use of these materials, there is a growing need to develop an optimal method of joining composite components and carrying out repairs following operational damage. One such method is bonding by means of adhesive bonds, many of whose properties are already quite well known. However, relatively little is known about the impact strength of adhesive joints in general, including adhesive joints of composite components. This paper presents a concept for conducting such tests using adhesive lap joints. The sample pieces were cut from a 9-layer, 2 mm thick composite panel made with an autoclave technique. The results show that the lowest impact strength and shear strength occurred for adhesive joints made with an epoxy adhesive with the highest Young’s modulus. The best results were obtained for the adhesive whose joints became destroyed in equal proportions in a cohesive–adhesive manner. Full article

Inconel 600 alloy has gained consideration as a favourable material for heat and power applications, particularly in turbine blades, due to its superior mechanical behaviour encompassing strength, toughness, oxidation resistance, and ductility. Tungsten Inert Gas (TIG) welding is one of the preferred techniques for joining these alloys. Therefore, the investigation of the mechanical behaviour after the welding process is crucial for selecting the appropriate technique for joining Inconel 600 sheets. This research focuses on investigating the microstructure and mechanical behaviour of TIG-welded Inconel 600 through a series of tests, such as tensile, fatigue, creep, and hardness evaluations. In addition, microstructural analysis is combined with these mechanical evaluations to simulate the operating conditions experienced by turbine blades. Key parameters such as yield strength, tensile strength, and elongation have been evaluated through these analyses. The Ramberg–Osgood relationship has been investigated using the engineering and true stress–strain curves obtained from the welded specimens. The results of the fatigue test illustrate the relationship between strain amplitude and the number of cycles to failure for single and double-edge notched specimens. The test was performed at two different loads including 400 MPa and 250 MPa at a constant temperature of 650 °C, and the corresponding strain-time curves were recorded. The results showed rapid creep failure at 650 °C, suggesting that TIG welding may need to be optimized for high temperature applications. Full article

A distance range join query (DRJQ) is a fundamental and critical operation in spatial database queries. It identifies geographic elements within specified distance ranges. This technique has a wide range of applications in multiple domains, including Geographic Information Systems (GISs), urban planning, and environmental monitoring. However, performing a DRJQ on large-scale spatial data remains a challenging problem, as the computational complexity of existing techniques escalates rapidly with increasing volumes of data. We propose PixelQuery, an efficient DRJQ method specifically optimized for visualization analysis. PixelQuery integrates spatial indexing with visualization-oriented strategies. It directly computes the display values of query results within the viewport, substantially lowering computational costs. Experiments conducted on datasets of varying scales demonstrate that this method can handle visualization queries involving tens of millions of elements on a standard laptop, with a maximum processing time of only 7.64 s. This technology provides a robust solution for rapid DRJQ processing and the visualization of large-scale vector data, offering promising potential for a diverse range of applications. Full article

The emergence of autonomous vehicles offers the potential to eliminate traditional traffic lanes, enabling vehicles to navigate freely in two-dimensional spaces. Unlike conventional traffic constrained by physical lanes, autonomous vehicles rely on real-time data exchange within platoons to adopt cooperative movement strategies, similar to synchronized flocks of birds. Motivated by this paradigm, this paper introduces an innovative traffic flow model based on the principles of particle swarm intelligence. In the proposed model, each vehicle within a platoon is treated as a particle contributing to the collective dynamics of the system. The motion of each vehicle is determined by the following two key factors: its local optimal velocity, influenced by the preceding vehicle, and its global optimal velocity, derived from the average of the optimal velocities of M vehicles within its observational range. To implement this framework, we develop a novel particle swarm optimization algorithm for autonomous vehicles and rigorously analyze its stability using linear system stability theory, as well as evaluate the system’s performance through four distinct indices inspired by traditional control theory. Numerical simulations are conducted to validate the theoretical assumptions of the model. The results demonstrate strong consistency between the proposed swarm intelligent model and the Bando model, providing evidence of its effectiveness. Additionally, the simulations reveal that the stability of the traffic flow system is primarily governed by the learning parameters $c_1$ and $c_2$, as well as the field of view parameter M. These findings underscore the potential of the swarm intelligent model to improve traffic flow system dynamics and contribute to the broader application of autonomous traffic systems management. In addition, it is worth noting that this paper explores the operational control of an AV platoon from a theoretical perspective, without fully considering passenger comfort, as well as “soft” instabilities (vehicles joining/leaving) and “hard” instabilities (technical failures/accidents). Future research will expand on these related aspects. Full article

Facing the widespread cooperation among different agribusiness entities in China, this study explores the impact mechanism of land scale on farmers’ cooperation with new agricultural business entities (abbreviated as NABEs), including family farms, cooperatives, and agribusinesses. The effects of income within the cooperation mechanism are further analyzed. Based on survey data from 1558 farmers in 10 provinces, applying binary Logit regression and mediation effect models, the study finds the following: (1) The current land area, past growth of land, and future willingness to expand land all positively affect farmers’ cooperation with new agricultural business entities; (2) An inverted U-shaped relationship exists between land size and the proportion of farmers joining new agricultural business entities. The probabilities of joining family farms, cooperatives, and agribusinesses peak at land sizes of 2.65, 6.82, and 7.04 acres, respectively; (3) The current income situation has an intermediary effect on the cooperation between farmers and family farms, while the future income expectation has an intermediary effect on the cooperation between farmers and cooperatives and agribusinesses; (4) The effect of land scale on cooperation is more significant for farmers of village officials or agricultural organization members, full-time farmers, and those with green production and modern sales. This study proposes a development growth curve of farmers, which can be divided into “self-development–cooperation–transformation” stages, and gives solutions for each stage, to facilitate moderate-scale operations and long-term cooperation among various entities in the context of market reforms and social division of labor. Full article

This article estimates the impact of government subsidies on productivity growth in South Africa, joining the ongoing debate among economists regarding the effectiveness of subsidies as a driver of industrial productivity. While some argue that subsidies address market failures, facilitate R&D, and improve efficiency, others criticise the attendant dependence, which reduces the incentive for industries to operate efficiently. This article contributes by examining the specific channels—efficiency and technical changes—through which subsidies affect productivity in South Africa. The analysis is based on a panel dataset comprising 64 three-digit industries observed between 1993 and 2023. Estimation is performed through an endogeneity robust panel stochastic frontier model, which treats subsidies as both an inefficiency driver and a technology variable. An additional estimation approach is proposed integrating the true fixed effects with a control function in a bid to account for both unobserved heterogeneity and idiosyncratic endogeneity. The results show that subsidies are detrimental to productivity, particularly through stifling technological progress. This result supports the view that subsidies reduce the incentive for beneficiaries to innovate. This evidence calls for a reevaluation and a possible restructuring of subsidy programmes in South Africa in a bid to mitigate their adverse effects on industrial productivity. Full article

The cleaning circuit of the collective Cu-Mo flotation plant at Collahuasi (north of Chile) consisted of two parallel flotation rows, each one of three first cleaner cells in series with six cleaner–scavenger cells. The second cleaner consisted of 10 parallel columns (6 rectangular and 4 circular), whose tailings were directly recycled to the first cleaner. Recently, a project was developed to upgrade the cleaning circuit by decreasing the large Mo circulating load and improving the cleaning circuit performance. For this purpose, a testing strategy was set up at a pilot scale to evaluate the use of intensified flotation (Jameson cells), mainly for collecting the fine Mo particles accumulated in the circulating load, which contributes to the Mo losses from the scavenger stage into the final tailings. The preliminary results regarding kinetics at the pilot scale showed good potential to improve the metallurgical performance of Mo and Cu, and a sensitivity study was carried out to evaluate the application of this technology in the industrial cleaning circuit. Then, two parallel Jameson cells were selected to re-treat the whole column tailings stream. This operation allowed for the generation of a direct final Cu-Mo concentrate (that joins the columns concentrate) while recycling their tailings to the first cleaner. After commissioning, three sampling campaigns were performed on the whole flotation plant, particularly on the overall cleaning circuit, to evaluate the impact of the new flotation cells. Results showed that the Jameson cells effectively decreased the minerals circulating loads in the cleaning stage, mainly for Mo (in 49%). The Jameson cells directly contribute 48% of Mo and 25% Cu of the minerals in the final concentrate and allow for increasing the Mo final grade (0.45% Mo vs. 0.29% from columns). These results were in good agreement with predictions from the pilot testing. Full article

The selection of a suitable plasma-facing material (PFM) that must protect the divertor, cooling systems, and structural components is an important challenge in the design of advanced fusion reactors and requires careful consideration. Material degradation due to melting and evaporation may lead to plasma contamination, which must be strictly avoided. Among the candidate materials, tungsten (W) is the most promising because of its thermo-mechanical and physical properties, which allow it to endure repeated exposure to extremely harsh conditions within the reactor. The plasma spraying (PS) technique is gaining increasing interest for the deposition of tungsten (W) coatings to protect heat sink materials, due to its relatively low cost, high deposition rates, and capability to coat complex-shaped surfaces and fix damaged coatings in situ. This review aims to provide a systematic assessment of tungsten (W) coatings produced by PS techniques, evaluating their suitability as PFMs. It discusses W-based materials, plasma spraying technologies, the role of the interface in joining W coating and metallic substrates such as copper alloys and steels, and the main issues related to coating surface erosion under steady-state and transient heat loads associated with advanced fusion reactor operation modes and off-normal events. Quantitative data available in the literature, such as porosity, oxygen content, thermal conductivity of the coatings, residual stresses accumulated in the coating–substrate interface, surface temperature, and material loss following heat load events, were summarized and compared to bulk W ones. The results demonstrate that, following optimization of the fabrication process, PS-W coatings exhibit excellent performance. In addition, previously mentioned advantages of PS technology make PS-W coatings an attractive alternative for PFM fabrication. Full article

Forming hybrid structures into complex shapes is key to address lightweighting of automotive parts. Recently, an innovative joining technique between aluminium and Carbon Fibre-Reinforced Polymer (CFRP) based on mechanical interlocking through sheet punching has been developed. However, scaling up the solution requires the assessment of challenges, such as multi-material forming and joint integrity, after forming operations. Therefore, this work proves the feasibility of forming aluminium–CFRP prepreg panels into complex omega-shaped profiles following a conventional cold-stamping process. Forming without defects was possible even in specimens featuring mechanical joints generated through punching. The effect of the CFRP position (in the inner or the outer side of the formed profile), the number of mechanical joints, the addition of a Glass Fibre-Reinforced Polymer (GFRP) intermediate layer to prevent galvanic corrosion and adequate lubrication on necking, cracking, springback behaviour and the final geometry after curing were studied. Compression tests were performed to assess the mechanical response of the hybrid profile, and the results showed that the addition of CFRP in the aluminium omega profile changed the buckling behaviour from global bending to axial folding, increasing the maximum compression load. Additionally, the presence of mechanical interlocking joints further improved the mechanical performance and led to a more controlled failure due to buckling localization in the geometric discontinuity. Full article

This study investigates price decisions in a queue with two servers, where customers exhibit retrial behavior. There is no waiting space. Arrival customers have the option to either join the system or balk; when the two servers are occupied, those who decide to enter become repeat customers. Two scenarios where the waiting lines in orbit are unobservable and observable are considered. We analyze customers’ behavior and derive their Nash equilibrium strategies under both cases. Additionally, we examine optimal pricing decisions aimed at maximizing profit and social welfare, respectively. Moreover, we demonstrate that these objectives often lead to divergent outcomes. Compared to a single-server queue, the reduction in customers’ sojourn time is more obvious when the waiting line is unobservable. Under certain conditions—such as a large potential market size, high customer impatience, or a low retrial rate—increasing the number of service personnel can enhance both profit and social welfare. Notably, a profit-maximizing manager is more incentivized to increase servers than the social planner. These findings provide valuable insights for balancing operational efficiency, profitability, and customer satisfaction in queue management systems. Full article