Mechanical Work Research Articles

Viscoelastic-Plastic and Elastic Components of Mechanical Work of Deformation of Polymer Textile Materials

Viscoelastic-Plastic and Elastic Components of Mechanical Work of Deformation of Polymer Textile Materials

Walking kinematics of ants carrying food in the mandibles vs. gaster

The locomotor behavior of an animal strongly depends on the distribution of its body mass. Whenever changes occur in this distribution, the displacement of the body center of mass (CoM) may lead to a loss of balance. Ants are an interesting biological model to investigate how an animal copes with such changes because, when they transport food, their CoM may be displaced from its usual position. We studied the ant Formica rufa whose diet consists mainly in liquid food, stored in the abdomen, but which also includes prey transported in the mandibles. We investigated the kinematics of locomotion of the same individuals while walking unloaded and while transporting food internally or externally. We found that the kinematics of locomotion slightly differed in the two types of transport. Ants transporting food in their mandibles adopted a more erect posture and tended to be more often in static instability than ants transporting food internally. In addition, the amplitude of the vertical oscillations of their CoM was higher, which led to a jerky locomotion. However, due to their erect position, the position of their overall CoM was actually not different from that of unloaded ants. Finally, the mechanical work achieved by ants to rise and accelerate their CoM was smaller in ants transporting food internally than in ants transporting food externally or in unloaded ants. This suggests that the morphology of F. rufa could make the transport of food in the gaster more mechanically efficient than the transport of food in the mandibles.

A weight-based efficiency measure for energy dissipating devices for flexible rockfall barriers

Flexible barriers are essential passive measures which are able to protect human life, structures and infrastructures from rockfall hazards. When a barrier is impacted, a significant portion of energy dissipation is concentrated in targeted components, named brakes, which can be replaced after the rockfall event. Several technologies exist, differing in both constitutive elements and energy dissipation mechanisms, but experimental data are generally restricted by producers. The present paper compares the various technologies thanks a new efficiency index, that is the ratio between the component potentially dissipated energy and its weight. To analyse the effects of the design parameters, four of the most common brakes are analytically modelled. It is shown that the performance of the devices is variable and depends on the working mechanism and the adopted material. In particular, plastic deformation energy dissipation induced by buckling is generally more efficient than the one caused by bending. Finally, a discussion on the force that activates the brake is proposed. The proposed analyses are of paramount importance for the conceptual design of new energy dissipation devices in rockfall risk mitigation structures.

Self-sufficient power plant prototype composed by cascaded disruptive power units doing work by isothermal contraction and expansion

This research work aims at the design and development of a disruptive prototype for a Self-sufficient power plant (SSPP) prototype composed by cascaded disruptive power units (PUs) doing work by isothermal contraction-expansion processes. The innovative design integrates thermo-hydraulic actuators enabled to drive hydraulic pumps connected to a hydraulic motor-generator. The prototype's cascaded PUs operates on a double closed processes-based isochoric-isothermal-isochoric-isothermal (VTVT) thermal cycle, enabled to do useful work by contraction and expansion of a thermal working fluid (TWF), which is notable for its high specific work output and high thermal efficiency. This is due to a disruptive cascaded heat recovering technique associated to a heat upgrading strategy. Among the most relevant Key Features are its self-sufficient operation modes that challenge traditional limitations of second-kind perpetual motion machines (PMMs) The expected capabilities on the basis of the consistency of empirical analysis are summarized as: - Design based on the optimal number of cascaded power units, - Efficient generation of useful mechanical work through expansion and contraction of the TWF, - High specific useful work (kJ/kg of TWF), such as helium, - Low ratio of actuator volume and weight to specific work. Preliminary tentative validation: The prototype design model was validated through case studies using air and helium as real TWFs. Empirical results demonstrate the SSPP's exceptional performance under certain conditional restrictions. - The optimal SSPP completed with nine cascaded PUs each operating on a double-VTVT cycle per PU. - Helium: RIT value of 0.9 and 9 PUs coupled in cascade to give an SSI of 156.72and a SSEP yield of 922.23 kJ/kg.cy. - Air: RIT value of 0.9 and 9 PUs coupled in a shell to give an SSI of 27.41 and a SSEP production of 37.67 kJ/kg.cy. These findings highlight the prototype's potential to significantly advance energy production efficiency and self-sufficiency in power generation systems.

Daily synchronous work interruptions: a social-exchange perspective

ABSTRACT Although work interruptions inherently involve social interactions, past research largely neglected the social aspects of interruptions. To better understand the social component of interruptions, our study focuses on the social exchanges between interrupters and interruptees. To do so, this study distinguishes between two interruption categories: interruptions serving to benefit employees who interrupt and interruptions serving to benefit employees who are interrupted. Focusing on interruptions via synchronous communication channels (face-to-face interactions and phone calls), we examined the implications of these two interruption categories for interrupted employees’ job satisfaction through three mechanisms (interpersonal citizenship behaviour, work engagement, and cognitive exhaustion). We analysed data from a two-week diary study with two daily measurements (N = 108employees; n = 799 days). Multilevel path modelling showed that interruptions serving to benefit interrupting employees were positively related to interrupted employees’ interpersonal citizenship behaviour. Moreover, interruptions serving to benefit interrupted employees were positively related to interrupted employees’ work engagement. Both interruption categories were unrelated to cognitive exhaustion. The interruption categories were indirectly positively related to interrupted employees’ job satisfaction via interpersonal citizenship behaviour and work engagement as mechanisms. Altogether, we offer a new perspective on interruptions, highlighting that the inherent social exchanges can benefit interrupted employees.

Stable Millivolt Range Resistive Switching in Percolating Molybdenum Nanoparticle Networks.

To overcome the limitations of the conventional Von Neumann architecture, inspiration from the mammalian brain has led to the development of nanoscale neuromorphic networks. In the present research, molybdenum nanoparticles (NPs), which were produced by means of gas phase condensation based on magnetron sputtering, are shown to be the constituents of electrically percolating networks that exhibit stable, complex, neuron-like spiking behavior at low potentials in the millivolt range, satisfying well the requirement of low energy consumption. Characterization of the NPs using both scanning electron microscopy and scanning transmission electron microscopy revealed not only pristine shape, size, and density control of Mo NPs but also a preliminary proof of the working mechanism behind the spiking behavior due to filament formations. Furthermore, electrostatics COMSOL Multiphysics simulations of the morphology of the NPs provided evidence that the stable switching is due to the as-deposited stellate Mo NPs creating high electric field strengths, while keeping them separated, not seen before in other percolating networks based on spherical NPs. Hence, our results show the working mechanism behind switching in percolating Mo NP networks and show that they are very promising for realistic neuromorphic systems.

Demonstration of a Validated Direct Current Wearable Device for Monitoring Sweat Rate in Sports

Sweat rate magnitude is a desired outcome for any wearable sensing patch dedicated to sweat analysis. Indeed, sweat rate values can be used two-fold: self-diagnosis of dehydration and correction/normalization of other physiological metrics, such as Borg scale, VO2, and different chemical species concentrations. Herein, a reliable sweat rate belt device for sweat rate monitoring was developed. The device measures sweat rates in the range from 1.0 to 5.0 µL min−1 (2 to 10 µL min−1 cm−2), which covers typical values for humans. The working mechanism is based on a new direct current (DC) step protocol activating a series of differential resistance measurements (spatially separated by 800 µm) that is gradually initiated by the action of sweat, which flows along a customized microfluidic track (~600 µm in width, 10 mm in length, and 235 µm in thickness). The device has a volumetric capacity of ~16 µL and an acquisition frequency between 0.010 and 0.043 Hz within the measured sweat rate range. Importantly, instead of using a typical and rather complex AC signal interrogation and acquisition, we put forward the DC approach, offering several benefits, such as simplified circuit design for easier fabrication and lower costs, as well as reduced power consumption and suitability for wearable applications. For the validation, either the commercial sweat collector (colorimetric) or the developed device was performed. In five on-body tests, an acceptable variation of ca. 10% was obtained. Overall, this study demonstrates the potential of the DC-based device for the monitoring of sweat rate and also its potential for implementation in any wearable sweat platform.

Research on Working Mechanism and Structural Optimization of High-Speed Bearing of Tricone Bits Based on Finite Difference Method

Abstract To analyze the working mechanism of the floating sleeve bearing of the cone bit, the life of the floating sleeve bearing was tested. The experimental results show that adhesive wear will form on the bearing surface with the increase in temperature, which is the main cause of bearing failure. This article establishes the Reynolds equation and energy equation of the oil film based on the theory of dynamic pressure lubrication of sliding bearings. The equation was numerically solved based on the finite difference method. It determines the rotational speed ratio at the equilibrium based on the trend of the frictional torque and then corrects the eccentricity in the iterative calculation process so as to analyze the tribological performance of the bearings in equilibrium under different clearance ratios. Among them, the improper configuration of the internal and external clearance ratio leads to the increase of the friction torque and the reduction of the bearing capacity. For floating sleeve bearings, the configuration with a large internal clearance and small external clearance should be adopted. Finally, the bearing structure is optimized and numerical calculations show that the tribological performance of the new type of bearings is significantly improved compared with that of ordinary cone bit bearings.

Experimental investigation of circumnutation-inspired penetration in sand

Probes that penetrate soil are used in fields such as geotechnical engineering, agriculture, and ecology to classify soils and characterize their propertiesin situ. Conventional tools such as the Cone Penetration Test (CPT) often face challenges due to the lack of reaction force needed to penetrate stiff or dense soil layers, necessitating the use of large drill rigs. This paper investigates more efficient means of penetrating soil by taking inspiration from a plant-root motion known as circumnutation. Experimental penetration tests on sands are performed with circumnutation-inspired (CI) probes that advance at a constant vertical velocity (v) while simultaneously rotating at a constant angular velocity (ω). These probes have bent tips with a given bent angle (α) and bent length (L1). The variation of the mobilized vertical force (Fz), torque (Tz.), and the mechanical work components with the ratio of tangential to vertical velocity (ωR/ν, whereRis the distance of the tip of the probe from the vertical axis of rotation) is investigated along with the effects of probe geometry, vertical velocity, and soil relative density (DR). The results show that the soil penetration resistance does not vary withv, but it increases asα,L1, andDRare increased.Fzdecays exponentially with increasingωR/v,Tzinitially increases and then plateaus, while total work (WT) shows little magnitude changes initially but later increases monotonically. The mechanisms leading to these trends are identified as the changes in the probe projected areas and mobilized normal stresses due to differences in probe geometry and the effects ofωR/von the resultant force direction and soil disturbance. The results show that CI penetration within a specific range ofωR/vleads to small increases inWT(i.e.,⩽25%), yet mobilizesFzmagnitudes that are 50%-80% lower than that mobilized during non-rotational penetration (i.e., CPT). This indicates that CI penetration can be adopted forin situcharacterization or sensor placement with smaller vertical forces, allowing for use of lighter rigs.

Light‐Emitting Perovskite Solar Cells: Genesis to Recent Drifts

Perovskite, a star material with extraordinary opto‐electronic properties has shown promising results in both perovskite solar cells (PSCs) and perovskite light‐emitting diodes (PeLEDs). Taking advantage of the similar configuration of PSCs and PeLEDs, next generation devices with dual functionality of light‐harvesting and light‐emission can be realized. Such devices hold enormous application prospects. However, the necessary tradeoff resulted from the opposite working principles required for each mode of operation and challenges such as non‐radiative recombination loss resulted from bulk and surface defects in perovskite films and mismatched energy levels have hindered mass production. To provide a roadmap for rationally designing efficient light emitting perovskite solar cells (LEPSCs), a comprehensive review focusing on operating principle, device architecture, recent developments and limitations is required. We begin with a brief overview of the basic principles underlying the working mechanism of LEPSCs such as photon to electricity conversion and viceversa. The focus of this review then shift towards deligently combining and overviewing the important breakthroughs reported in this newly developed field such as morphology optimization, defect passivation, interface engineering, energy level alignment and dimensional control. Finally, this work concludes with discussing future challenges and providing a roadmap for rational design of efficient and stable LEPSCs.

EPID-22. MUTATIONAL SIGNATURE ASSOCIATED WITH HALOALKANE EXPOSURE ENRICHED IN FIREFIGHTERS IN THE ADULT GLIOMA STUDY

Abstract Using data from The Cancer Genome Atlas (TCGA) and Glioma Longitudinal Analysis (GLASS), we identified specific environmentally related mutational signatures in glioma including a signature associated with haloalkane exposure (SBS42) from the Catalogue of Somatic Mutational Signatures (COSMIC). Haloalkanes are widely used commercially including in flame retardants and fire extinguishants and are an intriguing finding given an observed increased glioma risk in firefighters. To validate our findings, we use new study participants with data on occupation (not available in either TCGA/GLASS) from the University of California, San Francisco Adult Glioma Study (AGS) to compare mutational signatures in tumors from 17 persons with glioma and documented occupational exposure to firefighting with those of 18 matched glioma patients without history of firefighting. Using whole exome sequencing, we identified environmental exposure signatures in tumor tissue from firefighters as well as in non-firefighters who had other relevant occupational exposure (e.g. auto/truck mechanic work). In these data, glioma is largely associated with aging and mutational signatures relating to endogenous mutational processes that correlate with age, such as spontaneous or enzymatic deamination of 5-methylcytosine. However, some gliomas have detectable signatures associated with exogenous mutational processes, such as SBS42 haloalkanes. Thus, we confirm detection of haloalkane signatures in persons likely highly exposed, i.e. long-term firefighters. Identifying exogenous mutational processes in cancers are important as they may inform public health intervention strategy to reduce mutagenesis and prevent cancer inception. Identifying occupational correlates with SBS42, associated with occupational exposure to haloalkanes, will pinpoint occupational hazards that may be avoidable. This is especially important for glioma and other cancers where exogenous mutagenesis is not well established.

Geothermo-mechanical energy conversion using shape memory alloy heat engine

AbstractThe shift towards renewable energy sources like geothermal energy has become desirable due to the recurrent energy crisis and global warming challenges influenced by fossil fuels. Geothermo-mechanical energy conversion using shape memory alloy (SMA) heat engines presents a novel and sustainable approach for harnessing geothermal energy. Shape memory alloys, known for their ability to undergo reversible phase transformations driven by temperature changes, are ideal for thermal-to-mechanical energy conversion. This paper explores the design and performance of an SMA heat engine that utilizes geothermal heat sources to drive mechanical work. The engine operates by cycling between the high-temperature geothermal environment and a cooler sink, exploiting the shape memory effect to generate mechanical motion. By integrating geothermal energy and SMA technology, this system offers a potential solution for renewable energy generation, with applications in remote or off-grid locations. The paper also investigates output power and the thermodynamic efficiency. A model is formulated and the engine behavior is simulated. A series of experiments are conducted for engine output power and efficiency. The model is compared to the experimental data for validation. The engine developed a maximum power of 3.5, 8.5, and 11.5 watts at 60, 80, and 90 °C respectively. The proposed SMA-based geothermo-mechanical energy conversion system offers a promising solution for efficient, reliable, and scalable geothermal energy harvesting. This research contributes to the development of innovative, efficient geothermal energy conversion technologies, supporting global renewable energy goals and reducing greenhouse gas emissions. This innovative energy conversion mechanism could play a key role in the future of sustainable power generation.

In rod we trust-The evaluation of a virtual rod and frame test as a cybersickness screening instrument.

Although Virtual Reality (VR) holds massive potential, its applicability still faces challenges because some individuals experience cybersickness. This phenomenon includes general discomfort, disorientation, and/or nausea, and it threatens not only a pleasant user experience but also the user's safety. Thus, predicting a user's susceptibility without relying on screening questionnaires that focus on past experiences, would enable more pleasant, safer VR experiences, especially for first-time users. Hence, the current study uses the participant's controller input in a virtual Rod and Frame Test (RFT) as an effortlessly trackable performance measure. The RFT is an established method for measuring an individual's sense of verticality in visually displaced fields. It has been used in the context of simulator sickness and cybersickness. In line with the literature and the subjective vertical mismatch theory, a lower visual dependency is expected to be correlated positively with cybersickness. To evaluate the potential of the RFT as a screening method for cybersickness, a cybersickness-inducing virtual environment (the City) was deployed. In total, data from 76 participants were eligible for the statistical analysis. The study finds a positive correlation between lower visual dependency and cybersickness, but only for the group that took the RFT after experiencing the City and only for the post-RFT cybersickness ratings. As cybersickness symptoms were VR environment-specific, the predictive validity of the RFT considering the VR-specific attributes is limited. Further, other studies attributed different working mechanisms to explain the connection between visual dependence and cybersickness with conflicting evidence. Although the RFT is not applicable as a cybersickness screening method, the effect sizes suggest that the RFT could serve as an additional objective assessment of the individuals' current state during VR exposure. Future research should systematically explore interconnections between the various factors that contribute to cybersickness, pursuing the idea of open science for context sensitivity.

Implementation of the Web-Based K-Means Clustering Algorithm on Hypertension Levels in the Elderly at the Bungah District Health Center

This research was carried out at the community health center in Bungah sub - district with the aim that so that patients receive appropriate treatment, a web-based system is needed to group hypertension data into several classes (clusters). The method used in data grouping is the K-Means Clustering method . In this study, 100 hypertension data were grouped into 4 clusters . The hypertension data used consists of two attributes, namely systole and diastole, the working mechanism is to normalize the data first, then the system groups the data into groups that have the same characteristics. The system will display the results of the clustering process which consists of four (4) clusters , namely cluster 1 Isolated Systolic Hypertension, cluster 2 Grade 1 (mild hypertension), cluster 3 Grade 2 (moderate hypertension), and cluster 4 Grade 3 (high hypertension). The data used for clustering is 100 data from blood pressure checks of patients at the Community Health Center using a blood pressure monitor. The results of the last iteration of 100 hypertension data in the system were used as parameters for calculating the level of effectiveness, by comparing the data from the clustering test results to the data from diagnosis a which produced an effectiveness value of 80%.

Light-sensitive Ca2+ signaling in the mammalian choroid

The choroid is the thin, vasculature-filled layer of the eye situated between the sclera and the retina, where it serves the metabolic needs of the light-sensing photoreceptors in the retina. Illumination of the interior surface of the back of the eye (fundus) is a critical regulator of subretinal fluid homeostasis, which determines the overall shape of the eye, but it is also important for choroidal perfusion. Noted for having some of the highest blood flow rates in the body, the choroidal vasculature has been reported to lack intrinsic, intravascular pressure-induced (myogenic) autoregulatory mechanisms. Here, we ask how light directly regulates choroid perfusion and ocular fluid homeostasis, testing the hypothesis that light facilitates ocular fluid absorption by directly increasing choroid endothelial permeability and decreasing choroid perfusion. Utilizing ex vivo pressurized whole-choroid and whole-eye preparations from mice expressing cell-specific Ca2+ indicators, we found that the choroidal vasculature has two intrinsically light-sensitive Ca2+-signaling mechanisms: One increases Ca2+-dependent production of nitric oxide in choroidal endothelial cells; the other promotes vasoconstriction through Ca2+ elevation in vascular smooth muscle cells. In addition, we found that choroidal flow, or pressure, modulates endothelial and smooth muscle photosensitivity and trans-retinal absorption of fluid into the choroid. These results collectively suggest that the choroid vasculature exhibits an inverted form of autoregulatory control, where pressure- and light-induced mechanisms work in opposition to regulate blood flow and maintain fluid balance in response to changes in light and dark, aligning with the metabolic needs of photoreceptors.

Technical characteristics and development trend of third generation solar cells

The future of global sustainable energy systems is anticipated to heavily rely on photovoltaic solar energy (PV). This paper provides an analysis of third-generation solar cells, exploring their underlying working mechanisms, evaluating their performance metrics, and discussing both their advantages and disadvantages. Third-generation solar cells, which include perovskites, dye-sensitized cells, and organic photovoltaics, offer promising advancements over traditional silicon-based cells, such as higher efficiencies and potential for lower production costs. However, challenges like material stability, scalability, and long-term reliability hinder their widespread adoption. In offering a comprehensive examination of these advanced solar technologies, the paper aims to contribute to the understanding and progress of renewable energy solutions. It underscores the importance of continued research and innovation in overcoming the existing limitations of third-generation solar cells. The transition towards a future that relies more heavily on sustainable energy sources hinges on the ability to develop and implement efficient, reliable, and cost-effective solar technologies. The paper identifies these bottleneck issues and suggests pathways for overcoming them.

Cell Death Mechanisms

Cells and their building blocks ensure the maintenance of life by performing complex tasks such as taking in nutrients, excreting waste materials, producing energy, growth, division and reproduction. The form of intercellular communication and coordination is critical for the organism to grow, develop, and adapt to its environment optimally. The numerical balance of the cells that make up the organism is very important for it to survive in a healthy way. While new cells are being created in the living being, some of the existing cells are also eliminated through cell death, thus ensuring a stable balance. As new cells are generated within the organism, a portion of the existing cells undergoes elimination through the process of cell death, thereby maintaining a stable balance. To uphold this mechanism, various forms of cell death mechanisms are activated. Cell death occurs spontaneously, genetically or by other factors that are a part of the life of living things. It basically exists in two main forms. These are programmed and unprogrammed cell death. Cell death mechanisms are critical for the development, survival and health of living organisms. This process, which is basically divided into two main categories, is called programmed cell death (apoptosis) and unprogrammed cell death (necrosis). Programmed and unprogrammed cell death mechanisms are very important for the proper functioning of biological systems and the continuation of life. While programmed cell death (apoptosis) plays very important roles in the regulation and development of tissues, homeostasis, immune response and prevention of diseases, unprogrammed cell death (necrosis) is important in the rapid repair of tissue by clearing damaged cells and the clearance of pathogens. Understanding the way death mechanisms work is very important in terms of understanding the effects that may occur on a healthy continuation of life and in developing more effective methods in the treatment of diseases that may arise as a result. For these reasons, what death mechanisms are, their types, differences and working principles have been tried to be summarized in this study.

Inorganic‐Organic Composite Cathode Materials for Aqueous Zinc Ion Batteries

AbstractAs potential candidates for large‐scale energy storage systems, aqueous zinc‐ion batteries (AZIBs) have attracted more and more attention from researchers and investors. Tremendous efforts have been devoted to develop high‐efficient cathode materials for improving comprehensive performances of AZIBs. Recently reported inorganic‐organic composite (IOC) cathode materials exhibited excellent electrochemical performance and were generally superior to corresponding inorganic or organic cathode materials. This paper presents a timely review on recent progresses and challenges in IOCs for AZIBs. Preparation strategies of IOCs have been elaborated and categorized, recent advances and main working mechanisms of IOCs are exhibited with a focus on the analysis methods for mechanism studies, outlooks and challenges of IOC cathodes for AZIBs are outlined to guide their future development.

Electrode materials optimize operating voltage and switching speed in micro/nano plasma ultrafast devices

Abstract The trade-off between ultrahigh speed and low operating voltage is a major challenge in the continuous improvement of modern electronics. Although micro/nano plasma devices have demonstrated the potential of picosecond switching speed and high output power, surpassing traditional electronic devices, versatile methods for optimizing the operating voltage and switching speed are highly desired. Here, an optimization scheme based on the work function of the electrode materials is reported, which reduces the operating voltage and improves the switching speed. Compared with traditional methods, such as narrowing gaps or distorting electric fields, this approach offers advantages such as reducing production costs, enhancing consistency, and improving tunability. The experimental results show that using silver as a low-work-function electrode material can reduce the operating voltage by 55% to 180 V and increase the switching speed by 58% to 7.1 V/ps compared to platinum, which is equivalent to a 71% reduction in gap size. In addition, the underlying working mechanisms and inherent advantages of the approach are demonstrated, providing new insights for the ultrahigh switching speed and low-power application of micro/nano plasma devices, such as high-speed communication and ultrafast electronics.

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.