Break Research Articles

Auto‐Pressurized Multi‐Stage Tesla‐Valve Type Microreactors in Carbon Monoliths Obtained Through 3D Printing: Impact of Design on Fluid Dynamics and Catalytic Activity

AbstractThe present research exploits an innovative methodology for producing auto‐pressurized carbon microreactors with a precise and controlled structure analyzing the influence of their design on the fluid dynamics and their catalytic performance. Carbon monoliths with Tesla‐valve shape channels (Tesla, T, and modified Tesla, Tm) are synthesized through the combination of 3D printing and sol–gel process and further probed as Ni/CeO2 supports on CO2 methanation. The experimental results and mathematical modeling corroborated the improved performance obtained through the complex design compared to a conventional one. In addition to chaotic fluid flow induced by the deviation in flow direction, which improves the reagents‐active phase interaction, local pressure increases due to convergence of flows may enhance the Sabatier reaction according to Le Châtelier's principle. Conversely to straight channels, T and Tm are not affected by flow rate and presented chemical control. Tesla‐valve with curved angle (Tm) improved the mass transfer, achieving higher conversion and ≈30% reaction rate increase regarding right angle (T). Thus, this auto‐pressurized multi‐stage Tesla‐valve monolith opens the gate to design specific and advanced functional materials for multitude chemical reactions where not only the reactant‐active phase contact can be maximized but also the reaction conditions can be controlled to maximize the reaction kinetics.

Evidence for response inhibition as a control process distinct from the common executive function: A two-study factor analysis.

The dominant model of executive functions, which has held for over two decades, contends that various aspects of seemingly disparate forms of inhibitory control-for example, inhibiting a prepotent response, or inhibiting irrelevant thoughts and distractions-are in fact manifestations of a single latent executive function. Recent work, however, has cast doubt on this dominant model, as certain conditions can dissociate performance on tasks thought to index inhibitory control. Moreover, issues related to task reliability and latent estimation of inhibition processes have prompted questions about whether the structure of inhibitory control can even be reliably estimated at a latent level. We addressed these issues in two studies of healthy young adults (Study 1 N = 154, Study 2, N = 279), examining seven then 12 different tasks taken by prior research to assess inhibitory control. Contrary to the dominant model of executive functions, we found that, at a latent level, inhibitory control was best fit by a replicable two-factor solution, with response inhibition as a distinct executive function. Further, our data suggested that prior work on executive functions may not have observed a response inhibition factor due to task selections (i.e., including either one of two specific tasks was critical to identifying a separate response inhibition factor). Therefore, contrary to the current primary theoretical model of executive functions, these results suggest that response inhibition is, in fact, a distinct control process from the control process underpinning other forms of inhibition, which has important implications for designing interventions and assessing outcomes related to inhibitory control. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Knowledge sharing and NPD performance for UK cross – border M&A firms: the moderating role of behavior and outcome controls

Purpose This paper aims to explore how the effect of knowledge sharing through mergers and acquisitions (M&As) on new product development (NPD) performance is contingent upon two different types of control mechanisms: behavior control and outcome control. Design/methodology/approach Leveraging the theory from transaction cost economics, this study provides answers regarding the roles of behavior and outcome controls. The hypotheses were tested empirically across a sample of 143 UK cross-border M&A firms. Findings The results provide the increasing call for an integrative perspective and theory in the M&A literature in that knowledge sharing through M&As is deemed decisive for NPD performance, and while both control mechanisms are effective, behavior control is more effective in enhancing NPD performance than outcome control. Originality/value The relevant M&A studies lack insights into the use of control mechanisms as a way to monitor the target firm’s behavior and performance and reduce the risk of its opportunistic behavior. Appreciating the need for M&A literature that elaborates control strategy and structure, this study incorporates behavior control and outcome control into M&A mechanisms.

Flexible and Advanced DBS: A distributed control strategy for a DC[sbnd]Nanogrid

Nowadays, it is well known that the energy system is going towards a clear and necessary energy transition. New enabling technologies are needed to accelerate this transition, like the dc nanogrids. The dc nanogrids are designed for a bottom-up approach and play an important role due to their scalability and modularity features. To take advantage of these features, in this paper, the authors propose a flexible and advanced DBS distributed control strategy so to be independent from the dc nanogrid configuration and operating both in stand-alone and in the grid-connected mode. At this scope the dc nanogrid is modelled as the connection of multiple generic nodes and a hierarchical control architecture is applied as a single control structure. It facilitates the seamless transition between the operating modes, independently from the dc nanogrid configuration. The effectiveness of the proposed flexible and advanced DBS is validated by some experiments performed on a testbed integrating a dc nanogrid laboratory prototype.

Seismic performance of soft soil foundation with a new type of assembled wall tuned mass damper.

The design of tuned mass damper (TMD) parameters is influenced by the soil-structure-TMD coupling system; thus, it is important to consider the soil-structure interaction (SSI) for the vibration control effect of the TMD. Recently, the acquisition of TMD parameters considering soil-structure interactions has only remained at the theoretical stage, lacking relevant experimental verification. Traditional TMD face the problems of occupying a large building space, increasing construction costs, and non-replaceable components. In this study, an assembled wall-type damping TMD was designed. By comparing the dynamic response of the uncontrolled and controlled structures equipped with the newly assembled wall-type damping TMD in the shaking table test on a soft soil foundation, we analyzed whether the SSI effect was considered in the TMD design parameters on the damping effect of the newly assembled wall-type tuned mass damper. The TMD parameters optimized using the artificial intelligence algorithm were verified experimentally. The results indicated that the traditional TMD design parameters were discordant because the SSI effect was not considered. The SSI effect in the soil effectively reduces the dynamic response of the superstructure. By considering the SSI effect and improving the multi-population genetic algorithm, a wall-type damping TMD with optimized parameters can achieve a good damping effect.

THE IMPACT OF USING INTERNAL CONTROL UNDER THE ELECTRONIC OPERATING SYSTEM

Internal control tools constitute one of the modern frameworks approved by the Committee of Sponsoring Organizations (COSO). "And the one which takes into account setting the objectives first, then estimating the possibility of those objectives being exposed to threats, then internal control procedures are designed that reduce the risks, and at the same time provide reasonable guarantees for achieving the organization's objectives and introducing all modern developments into the system. The contemporary trend of internal control focuses on the integration between managing the risks to which the organization is exposed and the internal control frameworks (Enterprise Risk Management- Integrated Framework) and its abbreviation (ERM), which provides the organization Management in conditions of uncertainty related to risks and their probabilities to be able to create and preserve value. The continuous developments in internal control systems, on the one hand, and competition between economic units, on the other hand, have led to many challenges through the use of modern technology and the innovation of new methods of development, which required the development of all sub-systems of control, including internal control systems, and then review the internal control structure and the extent of its acceptance of this computer-based technology and the effectiveness of its devices in providing information that supports the system's ability to adopt it. Based on this, the research topic was divided into five sections. The first section dealt with the research methodology, the second section dealt with the theoretical framework of the internal control system, and the third section dealt with the problems and limits of using electronic computers. The fourth section was devoted to studying the impact of using computers. The electronic section focuses on the components of the internal control system, while the fifth section is dedicated to stating the most important conclusions and recommendations.

Knowledge-shareable adaptive deep dynamic programming for hierarchical generation control of distributed high-percentage renewable energy systems

The increased proportion of distributed renewable energy sources connected to systems leads to frequency regulation difficulty, such as uncoordinated algorithms, inconsistent optimization and control objectives, and long training time. This work proposes a knowledge-shareable adaptive deep dynamic programming (KSADDP) to improve the active control accuracy and generation economy of the proposed hierarchical generation control framework, which contains two-layer control structures. In the first layer, droop control is employed to optimize the outputs of controllable generators, follow the frequency changes, reduce frequency deviation, and improve the operation economy of battery energy storage systems. In the second layer, a KSADDP is proposed to mitigate local optimum and accelerate the hybrid cooperative structure optimization by sharing the parameters of neural networks. These two layers synergistically optimize control performance and reduce generation costs. The simulation results of a three-high-percentage renewable energy system show that: with two layers of cooperation and sharing training information, the KSADDP outperforms the comparison algorithms in seven evaluation indices and reduces the generation cost by 4.85%–7.41 % compared to the comparison algorithms. The proposed KSADDP cooperates the time scales between multiple layers, cooperates the objectives between multiple layers, increases the parameter-sharing process, and reduces training time.

Ice-Jam Investigations along the Oder River Based on Satellite and UAV Data

The Oder River, situated along the border between Poland and Germany, is regularly affected by ice-jam events and their associated hazards, such as a sudden rise in water level and the endangerment to flood-protection infrastructure. The existing databases on past ice-jam events lack substantial information considering ice formation, blockage origins or the spatiotemporal evolution of the ice cover needed for a comprehensive understanding of relevant ice processes. Within this study, the evaluation of satellite and Uncrewed Aerial Vehicle (UAV) data was carried out in order to analyze the capabilities of enhancing river ice information in the study area. Satellite imagery was proven to be a valuable source of investigating ice-jam phenomena on all scales, leading to the identification of initial ice-jam locations, surveying spatiotemporal ice cover evolution or monitoring the maximum ice-cover extent. A simplified approach for river ice classification of satellite radar data using the K-Means Cluster Analysis is introduced, enabling the differentiation between river ice formations. Based on UAV data taken in this study, workflows were presented, allowing for measurements of ice floe velocities and the localization of flooded and ice-covered flow control structures.

Leeds FAS2 FSR: environmental challenges for the design of an in-river control structure

As flood risk authorities look to counter increasing peak river flows due to a changing climate, traditional linear flood defences are in many cases proving to be an unsustainable method of managing flood risk. Full containment of flows in the river channel will require ever increasing defence heights, cutting off communities from their rivers and natural heritage. Upstream flood storage provides a potential alternative means of flood management, allowing the peak of the flood to attenuate and downstream river levels to be kept within a tolerable range. The Leeds Flood Alleviation Scheme Phase 2 (FAS2) uses a combined approach: linear defences are constructed in urban reaches and complemented by an online flood storage reservoir (FSR) upstream of the city. The FSR halves the annual probability of defences overtopping within the city centre from 1% to 0.5%, achieved through active variable flow control at the FSR. This paper explores some of the challenges faced in the design and construction the in-river flow control structure which is integral to the operation of the FSR. In particular this paper will consider some of the key environmental objectives for the scheme and offer considerations for working in a dynamic and environmentally sensitive fluvial environment.

Optimization of White Box Testing by Utilizing Branching and Repeating Structures in Java Programs Using Base Path

Software testing is a process created to detect anomalies in the operation of a program or system in order to achieve the expected results. White box testing is a software testing method that tests the internal structure, design and program code. This research aims to produce an optimization method for white box testing in Java programs by utilizing branching and repetition structures using the basis path method, as well as analyzing the effectiveness of the proposed method in generating test cases. The Java program tested in this research includes input function calls, loops, branching, and exception handling. Test case design is carried out by applying the basis path method to achieve comprehensive coverage. The test results show that the base path method is able to produce effective test cases for testing control structures without redundancy. Test case design is assisted by flowgraph and matrix graph modeling. It is hoped that this research can contribute to the optimization of white box testing techniques.

Continuous synthesis of calcium hydrogen phosphate dihydrate (DCPD) in an annular rotating flow loop reactor

The synthesis of calcium hydrogen phosphate dihydrate (DCPD) involves a gas–liquid-solid three-phase slurry system that poses challenges for precise control using traditional batch reactors to produce crystals with controlled morphologies and particle sizes. In this study, an annular rotating flow loop reactor (ARLR) was developed to continuously synthesize DCPD. The unique internal loop and annular rotating flow field of the reactor delivered exceptional plug-flow characteristics, ensuring that the obtained DCPD exhibited a controlled morphology and particle size. The morphology of DCPD was adjusted to be bowknot-shaped (BS) agglomerate crystals, reaching a length of 120 μm and a D50 size of 70 μm. The ARLR can achieve long-term stable operation with high-solid holdup slurries, outputting up to 125 g/h by maintaining precise and controllable flow and mixing conditions. Notably, ARLR marked a significant advancement in processing high-solid-holdup slurries, offering the adaptability to adjust the geometric design for various slurry systems and forecasting promising prospects.

Improved Reference Current Extraction Method for Electric Aircraft Active Power Filter Application

This paper proposes a robust reference current extraction method useful for active power filters (APFs) connected to the More Electric Aircraft (MEA) grid for addressing power quality issues. Hence, it is essential to investigate and develop better APF harmonic compensating control algorithms that can eliminate the impact of harmonics emerging from the nonlinear loads connected to the MEA grid. The proposed method envisages a half-cycle moving window discrete Fourier transform filter approach to rapidly extract the fundamental positive sequence (FPS) from a polluted three-phase grid voltage. Thus, allowing the harmonic cancelation method to generate desired clean reference current which is in phase with FPS component of the grid voltage. This reference current is used in conjunction with the hysteresis current controller to generate appropriate gate pulses for the current-controlled voltage source APF. The employment of the digital filter in the control structure of the APF ensures improved power quality for the MEA grid as compared to traditional filtering algorithms. The numerical and experimental results demonstrate that the proposed control solution helps to reduce the total harmonic distortion under abnormal grid disturbances, thus, indicating the potential benefits of the proposed work for addressing power quality issues in MEA applications.

Compliant variable admittance adaptive fixed-time sliding mode control for trajectory tracking of robotic manipulators

Abstract This paper presents a compliant variable admittance adaptive fixed-time sliding mode control (SMC) algorithm for trajectory tracking of robotic manipulators. Specifically, a compliant variable admittance algorithm and an adaptive fixed-time SMC algorithm are combined to construct a double-loop control structure. In the outer loop, the variable admittance algorithm is developed to adjust admittance parameters during a collision to minimize the collision time, which gives the robot compliance property and reduce the rigid collision influence. Then, by employing the Lyapunov theory and the fixed-time stability theory, a new nonsingular sliding mode manifold is proposed and an adaptive fixed-time SMC algorithm is presented in the inner loop. More precisely, this approach enables rapid convergence, enhanced steady-state tracking precision, and a settling time that is independent of system initial states. As a result, the effectiveness and improved performance of the proposed algorithm are demonstrated through extensive simulations and experimental results.

Dual-Threshold Control Architecture for Improved Thermal and Power Management in Open-Cathode Direct Methanol Fuel Cell

A new dual-threshold cascade control scheme is proposed for water management in direct methanol fuel cells. The control architecture is constructed with the goal of adjusting the liquid-level of a methanol solution in an internal storage tank, where this control structure is based on a set point constrained by upper and lower thresholds. The logic of the algorithm is driven by a noninverting and an inverting Schmitt triggers comprising a switching function that sets the master controller on manual mode for periods of time during which the operating temperature of the electricity-generating fuel cell’s stack can be fixed at an optimal value. Automatic control is implemented when either threshold is reached, triggering a level recovery action where the temperature is manipulated to promote or inhibit cathodic evaporative water losses, depending on the existing perturbations. Manual mode is reinstated when a chosen mid liquid-level target is reached. The strategy seeks to avoid water flooding and dry-out states in the device, while ensuring constant power and current production during periods of manual operation. Simulation studies show that the new control method is immune to severe perturbations, which stands in contrast to a standard cascade control scheme that causes significant degradation and unstable electrical performance in the cell under analogous conditions. Unlike the standard cascade control where the operating temperature is seldom close to the optimal operating point, the improved dual-threshold logic is superior such that the desired temperature of operation can be realized during the entire manual mode, enhancing the performance of the variables that critically depend on temperature. The new method realizes a successful power transition from 30 to 40W, demonstrating its ability to meet changes in load demands, where this transfer is implemented by altering the operational temperature from 45°C to 60°C at a constant voltage. The new strategy can be incorporated into a higher-level optimization control layer, where different temperature operating points can be chosen based on user-defined performance criteria. The study focuses on a case of two different points of the polarization curve corresponding to a power of 40W. While the operating point at a current of 2.51A and temperature of 57.5°C has a higher voltage efficiency of 10%, the second point operating at 2.79A and 50°C shows a boost by 7.6% in fuel efficiency over the first point. Hence, a user can choose the optimal operating condition based on specific performance metrics while simultaneously meeting the load demands. Few recommendations are presented to advance this work in the future.

Self-Calibration Method of Displacement Sensor in AMB-Rotor System Based on Magnetic Bearing Current Control

Displacement sensors are the key components of the active magnetic bearing rotor (AMB-rotor) system to realize the closed-loop control of the rotor displacement. The aging and failure of the displacement sensor components will lead to the changes of sensor sensitivity and zero point, which can directly affect the suspension performance of the rotor and even cause the instability of the AMB-rotor system. Therefore, it is significant to calibrate the sensor regularly. This paper proposes a self calibration method based on the detection and control of the magnetic bearing current without additional calibration equipment and hardware circuits. In addition, a new control structure of the AMB-rotor system is proposed to achieve efficient calibration, which can control the rotor displacement based on current following control method. Finally, experimental results verify the effectiveness of the proposed method on the displacement sensor calibration.

Research and application of small-diameter hydraulic fracturing in situ stress measurement system

Abstract. Observation and estimation of the stress state in the deep crust is a crucial challenge in in situ stress measurement work. The hydraulic fracturing method is an important borehole-based technique for absolute in situ stress measurement. The small-diameter hydraulic fracturing in situ stress measurement system described in this article consists mainly of underground measurement components (serial small-diameter packers and dual-circuit connecting installation rods) and surface control components (hydraulic fluid control system, data acquisition system, and high-pressure oil pump with controllable flow). It enables series measurement of small-sized boreholes for in situ stress and provides a maximum measurement range of 30–45 MPa. The subsequent calculation of in situ stress data adopts a uniform design method to discuss the influence of various external factors on rock fracturing values. The small-diameter hydraulic fracturing in situ stress measurement system has the advantages of simple and lightweight structure, short testing time, high success rate, and low requirements for rock integrity and pressurization equipment. It has formed a series of small-diameter in situ stress measurement equipment which has been innovatively promoted to the field of underground tunnel safety assessment in coal mines and metal mining areas. It has an important practical value and economic significance in accurately determining the in situ stress state of deep development areas.

A novel non-chemically amplified resist based on polystyrene-iodonium derivatives for electron beam lithography

To break the resolution limitation of traditional resists, more work is needed on non-chemically amplified resists (non-CARs). Non-CARs based on iodonium salt modified polystyrene (PS-I) were prepared with controllable molecular weight and structure. The properties of the resist can be adjusted by the uploading of iodonium salts on the polymer chain, the materials with a higher proportion of iodonium salts show better lithography performance. By comparing contrast curves and quality of the lithographic patterns, the optimum developing condition of 4-methyl-2-pentanone and ethyl alcohol (v:v = 1:7) was selected. The high-resolution stripes of 15 nm half-pitch (HP) can be achieved by PS-I0.58 in e-beam lithography (EBL). PS-I0.58 shows the advanced lithography performance in the patterns of 16 nm HP and 18 nm HP stripes with low line edge roughness (3.0 nm and 2.4 nm). The resist shows excellent potential for further pattern transfer, the etch selectivity of resist PS-I0.58 to the silicon was close to 12:1. The lithographic mechanism of PS-I was investigated by experimental and theoretical calculation, which indicates the polarity of materials changes results in the solubility switch. This work provides a new option and useful guidelines for the development of high-resolution resist.

Castor oil-based polyurethane Vitrimer modified asphalts regulated by dual dynamic reversible reactions and crosslinking density: Preparation, basic assessment and self-healing behavior

Thermosetting polymers, commonly used to improve asphalt properties, bring excellent pavement performance, but also pose significant challenges to the healing and recyclability of their modified asphalts after long-term service. An effective approach involves introducing dynamic bonds into the crosslinking networks to synthesize Vitrimer-modified asphalts with self-healing response. Due to the splendid mechanical properties, high elasticity, flexibility and easily controllable cross-linked structure of polyurethane, a novel castor oil-based polyurethane Vitrimer modified asphalt with disulfide bonds and Diels-Alder reactions was developed. Based on the prepared castor oil-based polyurethane Vitrimer (C-PUV, composed of components A and B) and its modified asphalts (C-PUVAs), a comprehensive study was conducted on the crosslinking density, mechanical properties, thermal stability, viscosity, compatibility, rheological properties, and self-healing behavior. The results indicated that C-PUVAs (C-PUVA1/C-PUVA2/C-PUVA3/C-PUVA4) exhibited sufficient retention times for viscosity, uniform phase distribution, and good high-temperature performance. The damaged C-PUVAs achieved a mechanical strength recovery rate more than 75 % after the first cycle of self-healing at 80 ℃ and 0.3 MPa. Furthermore, the crosslinking density of C-PUV was regulated by the segment length of component B. As the crosslinking density increased, C-PUV and C-PUVAs obtained higher mechanical strength while sacrificing part of self-healing efficiency. The mechanism is that increased crosslinking density altered the gel point distributions of the reversible crosslinked networks, resulting in a longer relaxation time and higher activation energy. In conclusion, the above findings provided valuable insights for developing bio-based polyurethane Vitrimer modified asphalts, and endosing thermosetting polymer modified asphalts with self-healing and recyclable properties.

A Survey on Cage‐based Deformation of 3D Models

AbstractInteractive deformation via control handles is essential in computer graphics for the modeling of 3D geometry. Deformation control structures include lattices for free‐form deformation and skeletons for character articulation, but this report focuses on cage‐based deformation. Cages for deformation control are coarse polygonal meshes that encase the to‐be‐deformed geometry, enabling high‐resolution deformation. Cage‐based deformation enables users to quickly manipulate 3D geometry by deforming the cage. Due to their utility, cage‐based deformation techniques increasingly appear in many geometry modeling applications. For this reason, the computer graphics community has invested a great deal of effort in the past decade and beyond into improving automatic cage generation and cage‐based deformation. Recent advances have significantly extended the practical capabilities of cage‐based deformation methods. As a result, there is a large body of research on cage‐based deformation. In this report, we provide a comprehensive overview of the current state of the art in cage‐based deformation of 3D geometry. We discuss current methods in terms of deformation quality, practicality, and precomputation demands. In addition, we highlight potential future research directions that overcome current issues and extend the set of practical applications. In conjunction with this survey, we publish an application to unify the most relevant deformation methods. Our report is intended for computer graphics researchers, developers of interactive geometry modeling applications, and 3D modeling and character animation artists.

ParDiff: Practical Static Differential Analysis of Network Protocol Parsers

Countless devices all over the world are connected by networks and communicated via network protocols. Just like common software, protocol implementations suffer from bugs, many of which only cause silent data corruption instead of crashes. Hence, existing automated bug-finding techniques focused on memory safety, such as fuzzing, can hardly detect them. In this work, we propose a static differential analysis called ParDiff to find protocol implementation bugs, especially silent ones hidden in message parsers. Our key observation is that a network protocol often has multiple implementations and any semantic discrepancy between them may indicate bugs. However, different implementations are often written in disparate styles, e.g., using different data structures or written with different control structures, making it challenging to directly compare two implementations of even the same protocol. To exploit this observation and effectively compare multiple protocol implementations, ParDiff (1) automatically extracts finite state machines from programs to represent protocol format specifications, and (2) then leverages bisimulation and SMT solvers to find fine-grained and semantic inconsistencies between them. We have extensively evaluated ParDiff using 14 network protocols. The results show that ParDiff outperforms both differential symbolic execution and differential fuzzing tools. To date, we have detected 41 bugs with 25 confirmed by developers.