Mechanical Work Research Articles

Reliable and Faithful Generative Explainers for Graph Neural Networks

Graph neural networks (GNNs) have been effectively implemented in a variety of real-world applications, although their underlying work mechanisms remain a mystery. To unveil this mystery and advocate for trustworthy decision-making, many GNN explainers have been proposed. However, existing explainers often face significant challenges, such as the following: (1) explanations being tied to specific instances; (2) limited generalisability to unseen graphs; (3) potential generation of invalid graph structures; and (4) restrictions to particular tasks (e.g., node classification, graph classification). To address these challenges, we propose a novel explainer, GAN-GNNExplainer, which employs a generator to produce explanations and a discriminator to oversee the generation process, enhancing the reliability of the outputs. Despite its advantages, GAN-GNNExplainer still struggles with generating faithful explanations and underperforms on real-world datasets. To overcome these shortcomings, we introduce ACGAN-GNNExplainer, an approach that improves upon GAN-GNNExplainer by using a more robust discriminator that consistently monitors the generation process, thereby producing explanations that are both reliable and faithful. Extensive experiments on both synthetic and real-world graph datasets demonstrate the superiority of our proposed methods over existing GNN explainers.

A review of teacher language awareness (2015-2024): Current trends and future directions

Teacher language awareness (TLA) encompasses language teachers’ competencies in using language, analyzing language, and teaching language (Lindahl, 2019). As these competencies directly influence how teachers teach language and the effectiveness of their instruction, TLA has garnered growing interest in recent years, resulting in an expanding body of research. Against this backdrop, this review first briefly clarifies the definitions and boundaries of TLA, highlighting the importance of integrating critical language awareness into TLA. It then analyzes the working mechanisms of TLA, followed by a selective review of empirical research (2015-2024) on the effect of TLA on teachers’ beliefs and practices, the current state of TLA, mediating factors, and the strategies for developing TLA. The review concludes by emphasizing the relevance of social and power dynamics in TLA and discussing current trends and future directions for TLA research.

Spatio-Temporal and Mechanical Analysis of Bench Press Phases: Barbell Kinematics and Dynamics Across Different Load Intensities

This study aimed (1) to explore the spatio-temporal phases of the execution of the bench press (BP) exercise based on barbell acceleration and power; (2) to describe barbell velocity, acceleration, mechanical power, and mechanical work at different load intensities; and (3) to analyse differences in kinematic and mechanical parameters. Twenty-one men (21.4 ± 1.5 years; 175.1 ± 6.7 cm; 75.8 ± 7.7 kg; 1RM: 91.7 ± 13.7 kg) and nine women (21.7 ± 2.3 years; 163.3 ± 10.8 cm; 57.2 ± 6.8 kg; 1RM: 38.9 ± 10.5 kg) were evaluated during the eccentric and concentric phases of the BP at different load intervals: interval 1 (55 to 75% 1RM), interval 2 (>75 to 85% 1RM) and interval 3 (>85 to 100% 1RM). Both temporal (duration) and mechanical variables (velocity, acceleration, mechanical power and mechanical work of the barbell) were determined using the Xsens MVN Link System. Mechanical variables were compared among the three different intervals. Interval 3 displayed greater duration compared to intervals 1 and 2. Barbell acceleration and power showed four different phases of BP movement, corresponding to the second and third phases of the exercise, bar braking (eccentric) and bar acceleration (concentric), respectively; the first and fourth phases are mainly determined by gravity instead of muscle intervention. Velocity and acceleration were different among the three different intervals during both the eccentric and concentric phases (p < 0.05). No differences were found between intervals 2 and 3 in mechanical power or mechanical work during the eccentric phase. In conclusion, the BP exercise has four phases considering barbell acceleration and power. The maximum and mean velocity and acceleration during BP performance decrease as load intensity increases. Maximum and mean mechanical power, and mechanical work, decrease progressively in the second and third intervals for both the eccentric and concentric phases. Thus, kinematics and mechanical parameters vary depending on load intensities.

Study on the relationship between Russia and the International Criminal Court

In 2016, after 16 years of review period, Russia finally made the decision not to join the International Criminal Court and the Rome Statute, from support to doubt to reject, the change of Russia's position is not only a direct reaction to the investigation of Russian cases in recent years, but also out of the interests of the state, the interests of the legal system, and the doubt of the working mechanism of the International Criminal Court. Although it does not formally join the International Criminal Court, Russia still needs to bear certain international legal obligations, especially in the face of the possible compulsory jurisdiction of the International Criminal Court, Russia needs to take corresponding measures in international law and domestic law to avoid the adverse impact.

Alternative energy in Spain and Chile. Forecasts and prospects in the context of the energy transition

The article provides a comparative analysis of the actions and achievements of two states, the Kingdom of Spain and the Republic of Chile, in the field of green energy. Over the last decade both countries have done extensive work on decarbonization of the economy and have become one of the leaders in their regions in terms of the pace of implementation of the energy transition. At the same time the strategies and mechanisms of work of the two states in the field of alternative energy development differ in many respects. Under certain comparable conditions and prerequisites for the development of the industry, with an identical share of alternative sources in the energy sector, Spain and Chile achieved different socio-economic indicators. In order to identify the potential for renewable energy development in Spain and Chile, the authors identified three factors of economic, political and energy character, based on which a forecast for the achievement of green energy targets in accordance with the state strategies of the countries was developed.

Seismic Performance Research on a Graded-Yielding Metal Brace with Self-Centering Functions

With the aim of achieving a graded-protection braced frame structure and minimizing the excessive residual deformation of traditional metal dampers under intense seismic action, a graded-yield-type metal self-centering brace (SC-GYMB) is proposed. The brace is composed of X-shaped and U-shaped steel plates with different yield point displacements, which jointly dissipate energy. Additionally, it employs a composite disc spring as a self-centering element to provide restoring force for the brace. The brace’s basic structure and working mechanism are described, and the theoretical model for its restoring force is derived. The ABAQUS finite element software (ABAQUS 2021) is utilized to investigate the hysteretic performance of the SC-GYMB under low-cycle reciprocating load, while thoroughly discussing the influence of various model parameters on its key mechanical behavior. The results demonstrate a strong agreement between the theoretical restoring force model and the numerical simulation results. The hysteretic curves of the braces exhibit a distinct “flag” characteristic, indicating excellent energy dissipation capacity and self-centering performance. Moreover, these curves display a hierarchical yield behavior that satisfies the seismic performance requirements for different intensity earthquakes. The deformation mechanism of X-shaped steel sheets transitions from bending deformation during the initial loading stage to tensile deformation in the subsequent loading stage. Increasing the initial pre-compression force of the combined disc spring enhances the restoration performance of the brace. Augmenting the thickness of X-shaped or U-shaped steel sheets modifies the displacement and load at both the first and second yield points, thereby enhancing energy dissipation capacity and bearing capacity of the brace; however, it also leads to increased residual deformation.

Taxonomy of Antioxidants to Deactivate Reactive Superoxide for Rejuvenating Batteries.

In lithium batteries employing oxygen electrochemistry as their cathodic process, superoxide radical is recognized as a reactive nucleophile that decomposes electrolytes and therefore deteriorate battery durability. Herein, we categorized the antioxidants employed for deactivating reactive superoxide in batteries into three groups after their working mechanisms were clearly understood and classified. Radical scavengers, as the first group, are sacrificed to provide moieties to neutralize the radical activity of superoxide. The reversible superoxide dismutase mimics (SODm's), distinguished from radical scavengers by their catalytic turnover, were divided into two families in terms of the anti-aging mechanism: electron-mediating SODm (e-SODm) and chemo-catalytic SODm (c-SODm). The redox-active e-SODm family, as the second group, mediates an electron from a superoxide radical to another superoxide, driving oxidation to dioxygen and reduction to peroxide, respectively. The c-SODm family, as the third group, chemically catalyzes superoxide disproportionation reaction, lowering the activation energy of the dismutation between the same radicals.

A Mini‐Review: The Rise of Triple‐Junction Silicon‐Perovskite‐Perovskite Solar Cells

Recently, the multijunction (MJ) solarcells have gained interest and have a lot of promise going forward. As MJ solarcells with an increasing number of absorber layers can reduce the thermalization and the nonabsorption losses of the device, it has then been proposed to overcome the Shockley–Queisser (S–Q) maximum efficiency limit. The preparation of the metal halide perovskite using a solution processing method with tunable bandgaps has made them an ideal candidate to integrate with the silicon photovoltaic, forming MJ silicon‐perovskite (Si‐PVK) solar cells. Benefitting from these, 33.90% power conversion efficiency (PCE) has been realized for the Si‐PVK MJ solar cell, which is comparable to the S–Q maximum efficiency limit in the range of ≈1.10–≈1.30 eV. Furthermore, the PCE of Si‐PVK solar cells can potentially increase with increasing the number‐junction of perovskite device. Taking advantage of this, the research on the triple‐junction (TJ) silicon‐perovskite‐perovskite (Si‐PVK‐PVK) solar cells has gained attention, although it is still in an early stage of development. In this mini‐review, the working mechanism, the design principle, and the progress of TJ Si‐PVK‐PVK solar cells are discussed. Finally, future outlooks in this field are also provided.

A review on pharmaceutical pollutants removal in water solution by catalytic ozonation using zeolite

AbstractThe presence of pharmaceutical pollutants in water sources constitute a serious risk to human health and the environment. Catalytic ozonation has emerged as a promising strategy for reducing these pollutants. This procedure uses ozone with the help of catalysts to improve the oxidation of organic molecules. Recently, there has been a lot of interest in using zeolite as an ozonation catalyst in the elimination of pharmaceutical contaminants from water solutions. Zeolites have unique properties such as their high surface area, porosity, and ion‐exchange capabilities, that make them effective catalysts for the decomposition of ozone and the oxidation of organic pollutants into harmless byproducts. This study aims to investigate the efficiency of zeolite catalytic ozonation in the elimination of pharmaceutical pollutants from aqueous solutions encompassing the working mechanisms, the determinants affecting the process's efficiency, potential obstacles, and perspective avenues for advancement within this field.

Study on the mechanical properties of geogrid-reinforced tunnel slag and particle breakage

The use of tunnel slag as roadbed filling can save resources and promote the sustainable and low-carbon development of transportation infrastructure.. To investigate the mechanical properties evolution law of tunnel slag as subgrade filler, SEM and large-scale triaxial tests were conducted to analyze its macroscopic, microscopic characteristics and particle breakage behavior. The study focuses on the impact of geogrid on the shear strength, deformation, and particle breakage of tunnel slag and its working mechanism. The results indicate that an increase in soft rock content reduces the shear strength and weakens its dilatancy. The average peak shear strength of grid reinforced dense specimens can be increased by 10%, and the residual shear strength can be increased by about 30%. The relative breakage index increases in an S-shaped pattern with increase in soft rock content. Higher confining pressure and soft rock content leads to more particle breakage, however, particle breakage in the reinforced specimens can be significantly reduced. The research findings contribute to the enhanced design and implementation of waste material repurposing, thereby advancing the sustainable development of infrastructure.

High-intensity interval training with blood-flow restriction enhances sprint and maximal aerobic power in male endurance athletes.

We investigated the concurrent impact of HIIT and blood-flow restriction (BFR) as a novel approach to further enhance maximal aerobic and anaerobic physiology and performances in trained athletes. In a randomized controlled trial, eighteen endurance-trained males (V ̇O2peak 65.6±5.1 ml.min-1.kg-1) included three sessions of HIIT per week (sets of 15-s efforts at 100% maximal aerobic power, interspersed by 15-s recovery) into their usual training for three weeks, either with restriction imposed on both lower limbs at 50-70% of arterial occlusion pressure (BFR group, n=10) or without (CTL group, n=8), and were tested for sprint and endurance exercise performance. The total mechanical work developed during a 30-sec Wingate test increased only in BFR (3.6%, P=0.02). During the Wingate, changes in near-infrared spectroscopy-derived vastus lateralis muscle oxygenation (Δ(deoxy[Hb+Mb]), % arterial occlusion) were attenuated after BFR training (-8.8%, P=0.04). The maximal aerobic power measured during an incremental cycling test increased only in BFR (4.5%, P=0.0004), but there was no change in V ̇O2peak among groups. Both groups improved 5-km cycling time trial performance, but BFR displayed a concomitant greater elevation in [H+] (11%, P=0.02). Changes in other blood variables (e.g., pH, lactate, bicarbonate and potassium ion concentration, hemoglobin) were not different between groups. Combining short-duration HIIT performed at 100% aerobic power with BFR elicited greater changes in sprint performance and maximal aerobic power in endurance athletes, associated with locomotor muscle metabolic adaptations but no meaningful effect on cardiorespiratory fitness.

Synthetic Jet Actuators for Active Flow Control: A Review

A synthetic jet actuator (SJA) is a fluidic device often consisting of a vibrating diaphragm that alters the volume of a cavity to produce a synthesized jet through an orifice. The cyclic ingestion and expulsion of the working fluid leads to a zero-net mass-flux and the transfer of linear momentum to the working fluid over an actuation cycle, leaving a train of vortex structures propagating away from the orifice. SJAs are a promising technology for flow control applications due to their unique features, such as no external fluid supply or ducting requirements, short response time, low weight, and compactness. Hence, they have been the focus of many research studies over the past few decades. Despite these advantages, implementing an effective control scheme using SJAs is quite challenging due to the large parameter space involving several geometrical and operational variables. This article aims to explain the working mechanism of SJAs and provide a comprehensive review of the effects of SJA design parameters in quiescent conditions and cross-flow.

Liquid-Solid Triboelectric Nanogenerator-Based DNA Barcode Detection Biosensor for Species Identification.

DNA barcode detection method is widely applied for species identification, which is imperative to evaluate the effect of human economic activities on the biodiversity of ecosystem. However, the wide utilization of existing detection biosensors is limited by bulky and expensive instruments, such as Raman spectroscopy and electrochemical station. Herein, a liquid-solid triboelectric nanogenerator (TENG)-based DNA barcode detection biosensor is proposed, which consists of water flow, fluid channel, and PDMS film attached by specifically designed capture probe. Through sequentially combining capture probe, targeted DNA barcode, and signal probe with Au nanoparticles (NPs), the surface charge density of friction layer of TENG decreases under the effect of AuNPs, verified by the density functional theory (DFT) method. Consequently, the peak value of output current spike signal for targeted DNA is smaller than that for other DNA, which is the working mechanism of the present TENG-based biosensor. Such biosensor successfully recognizes Alvinocaris muricola among different types of Alvinocarididae shrimps, and its low limit detection can reach 1×10-12m. The present work provides a paradigm-shift way to develop an inexpensive and accurate technique to detect DNA barcode for species identification, and paves a novel way for the application of liquid-solid TENG.

Observing Mixed Chemical Reactions at the Positive Electrode in the High-Performance Self-Powered Electrochemical Humidity Sensor.

Electrochemical humidity (ECH) sensors that integrate power generation and humidity sensing have attracted great research attention in recent years. However, the design of high-performance ECH sensors faces many challenges. Namely, the working mechanism of the ECH sensors is still controversial, and related self-powered applications have not been well implemented. To overcome these limitations, this study constructs an ECH sensor with high power-generation and humidity-sensing performance using the KCl/carbon black/halloysite nanotubes (KCl/CB/HNTs) as a humidity-sensing electrolyte. The proposed ECH sensor has a wide humidity-sensing response of 10.9%-91.5% relative humidity (RH), and a single ECH sensor can output 1.46 V with a maximum power of 133.2 μW at 91.5% RH. Particularly, the unprecedented mixed chemical reactions at the positive electrode, including the hydrogen evolution reaction and oxygen reduction reaction, are analyzed using multiple characterization and testing techniques. The analysis results provide solid experimental evidence for the current controversial working mechanism of ECH sensors. Due to the advantage of high-power generation, the proposed ECH sensor can be used for self-powered humidity detection. This study provides a valuable reference for improving the power generation of ECH sensors and solid evidence for clarifying their working mechanism, which could be beneficial for guiding the future development of ECH sensors.

Improved photoresponse performance of self-powered solar-blind UV photodetectors based on n-Si/n-Ga2O3/p-Li:NiO dual-junction

The solar-blind photodetectors (SBPDs) based on the wide-bandgap semiconductor gallium oxide (Ga2O3) exhibit significant potential for applications in military, civilian, and medical fields. Although multiple structural designs of Ga2O3-based SBPDs have been proposed, their performance typically falls short of commercial standards. However, the photoresponse speed of most self-powered PDs decreases rapidly in the solar-blind region. To address this issue, we first prepared high-quality single-crystal β-Ga2O3 films using RF magnetron sputtering, which exhibit an average transmittance exceeding 85% across the 400–800 nm range and possess a relatively smooth surface. Subsequently, a superior performance self-powered SBPD of vertical structure of n-Si/n-Ga2O3/p-Li:NiO dual-junction was fabricated, which possesses a responsivity of 0.18 mA/W, a photo-to-dark current ratio of 395, rapid rise/decay times of 132/148 ms, and a specific detectivity of 1.57 × 109 Jones at 0 V bias under 254 nm illumination. The photocurrent of the device fully recovered to its initial level after experiencing changes in ambient temperature [from room temperature (RT) to 100 °C and back to RT], demonstrating robust stability in harsh environments. In addition, the valence band structures of p-Li:NiO and n-Ga2O3 were investigated in detail using XPS, and the working mechanism of the devices was analyzed based on the Fermi level alignment. The excellent performance of PDs can be attributed to the increased depletion layer width, which generates more photogenerated carriers. Additionally, the separation and transmission of photo-induced carriers are enhanced by the superposition of a double built-in electric field. Our strategy offers a promising approach for achieving high-performance Ga2O3-based photovoltaic PDs.

SOCIAL RETURN ON INVESTMENT (SROI) ANALYSIS OF THE ELECTRIC MOTOR CONVERSION TRAINING PROGRAM IN NORTH LAMPUNG

Converting conventional motors into electric vehicles can reduce dependence on fossil fuels. The conversion process involves engine replacement, charging system installation, and vehicle structure modification. The conversion program was carried out involving workshops and vocational high school students. The Social Return on Investment (SROI) method was employed to measure the social and economic impacts of the program, involving impact identification, measurement, monetization, cost comparison, and analysis. The PLN Cares program undertook motor conversion with the aim of improving sustainability and quality. The research problem and objectives focused on measuring the SROI in the electric motor conversion program. The research method employed a qualitative approach with data collection techniques through in-depth interviews, focus group discussions, observations, and literature studies. Data were continuously analyzed during and after collection. SROI calculations involved initial investment capital input and impact value, resulting in an SROI ratio of 5.03. The research results indicated that the PLN Cares program had a significant social impact, with an SROI ratio indicating a profitable investment value. Conclusions and recommendations involved maintaining the working mechanisms, synergy among stakeholders, and using the program as a guide for similar projects in the future.

Insight into gain and transient response characteristics of AlGaN/GaN hetero-junction based UV photodetectors: Case study on the role of incident light intensity

Gain and response speed are two key performance parameters for high sensitivity photodetectors (PDs). However, the effect of incident light intensity on gain and transient response properties of AlGaN/GaN hetero-junction based PDs are still not fully understood. Here, we design and fabricate an AlGaN/GaN hetero-junction based ultraviolet (UV) PD with interdigitated electrodes formed by a conductive two-dimensional electron gas (2DEG) channel, which exhibits a low dark current of 2.92 × 10−11 A and a high responsivity of 3060 A/W at 10 V bias. The high-gain AlGaN/GaN 2DEG PD has a similar working mechanism to those of traditional phototransistors, but its device architecture is evidently simplified. By investigating the variation of gain and transient response characteristics of the 2DEG PD as a function of incident UV light intensity, it has been concluded that the gain of the PD in a low-light intensity region is dominated by hole accumulation-induced electron escape from the 2DEG, while in a high-light intensity region, the gain is dominated by photoconductivity effect and limited by carrier recombination. This study provides guidance for future practical applications of AlGaN/GaN-based PDs in complex UV illumination environments.

Numerical study of Mg(OH)2/MgO thermochemical heat storage reactor coupled with parabolic dish solar system

Systems coupling Mg(OH)2/MgO thermochemical reactor with parabolic dish solar collector (PDSC) have a potential application prospect in solar seasonal heat storage. However, their working mechanism has not been systematically studied and not well understood either. In this study, Mg(OH)2-based thermochemical reactor, which was coupled with PDSC, was numerically studied for the first time using a three-dimensional model. The various working conditions and influencing factors of PDSC system were investigated, and a comprehensive analysis and optimization for the heat storage performance of the reactor such as the reaction time and energy storage rate were conducted. Effects of the fluid inflow temperature, velocity, and fluid pipe distribution on heat storage performance were also unfolded. For instance, when the heating pipe was arranged at 70 mm from the central axis, the reaction time was 15.9 % less than that of evenly arranged at R/2 from the center. Moreover, fins were added to the reactor and the fin shape was optimized using the density-based topology optimization method. It was found that the reaction time was reduced by 42.4 % and was only 12614 s.

Comprehensive overview of detection mechanisms for toxic gases based on surface acoustic wave technology

Identification and detection of toxic/explosive environmental gases are of paramount importance to various sectors such as oil/gas industries, defense, industrial processing, and civilian security. Surface acoustic wave (SAW)-based gas sensors have recently gained significant attention, owing to their desirable sensitivity, fast response/recovery time, wireless capabilities, and reliability. For detecting various types of targeted gases, SAW sensors with different device structures and sensitive materials have been developed with diversified working mechanisms. This paper is focused on overviewing recent advances in working mechanisms and theories of dominant sensitive materials and key mechanisms/principles for targeting various gases in the realm of SAW gas sensors. The basic sensing theories and parameters of SAW gas sensors are briefly discussed, and then the major influencing factors are systematically reviewed, including the effects of various sensitive layer materials, temperature/humidity, and UV illumination on the overall performance of SAW gas sensors. We further highlight the relationships and adsorption/desorption principles between sensing materials and key targeted gases, including NH3, NO2, H2S, explosive gases of H2, and 2,4,6-trinitrotoluene, and organic gases of isopropanol, ethanol, and acetone, as well as others gases of CO, SO2, and HCl. Finally, we discuss key challenges and future outlooks in designing methodologies of sensing materials and enhancing the performance of SAW gas sensors, offering fundamental guidance for developing SAW gas sensors with good sensing performance.

Biomimetic nanozyme-based electrochemical sensor integrated with microfluidic cell for on-site uric acid detection

Uric acid (UA) is the key indicator highly associated with gout, and on-site UA detection is of great significance for personalized health management. Herein, we propose an integrated microfluidic electrochemical sensing platform for real-time UA detection. The platform mainly consists of a biomimetic nanozyme-based electrochemical sensor and a microfluidic cell. The biomimetic nanozyme with desirable catalytic activity can effectively promote UA oxidation, and the corresponding working mechanism is clarified through density functional theory calculation. Besides, the well-designed microfluidic cell is capable of impurity removal and sample storage. Based on these designs, the whole process of sample pretreatment and target detection can all be achieved on one integrated platform, allowing for user-friendly test. This developed platform shows satisfactory sensing performance for UA with a detection limit of 4.2 μM. In addition, it is successfully applied to UA determination in artificial saliva and serum samples, showing desirable application prospects in clinical diagnosis.