Noise source analysis of porous fairings in a scaled landing gear model

This paper presents an experimental investigation into the aeroacoustic and aerodynamic impact of various flow-permeable fairings having different levels of airflow resistivity, including wire meshes, perforated plates, and 3D-printed materials based on the repetition of diamond-lattice unit cells. The fairings are installed upstream of a scaled LAGOON landing gear model, which incorporates a torque link and brake-like protuberances to replicate realistic noise sources. Acoustic-imaging measurements carried out on the baseline model reveal that these additional components contribute significantly to far-field acoustic radiation, altering both the location and strength of dominant noise sources. The flow-permeable fairings decrease the model loading and turbulence kinetic energy in its wake compared to a fully solid configuration due to less abrupt flow deflection, with a positive impact on undesired noise possibly arising from interactions with downstream, uncovered gear components. Furthermore, fairings characterized by high airflow resistivity offer comparable or superior sound reductions to the solid fairing within a frequency range where the self-noise produced by the airflow through material pores does not dominate. Beyond generating an extensive dataset to support the validation of numerical simulations, this study provides valuable insight into the development of innovative and more efficient passive sound-control solutions for landing gear systems

Atmospheric environment shapes surface reactivity of Fe(0)-doped lunar dust simulant: Potential toxicological implications

The toxicity of lunar dust (LD), anecdotally reported by Apollo astronauts, raises concerns for future missions involving prolonged human presence on the Moon. LD toxicity is thought to involve oxidative stress driven by nanophase metallic iron (np-Fe0), a peculiar feature of LD. In life-supporting lunar habitat, np-Fe0 embedded in the amorphous phases of LD may react with O2 prior to accessing the lung, complicating toxicity assessments. Due to limited availability of real LD samples, toxicological evaluations rely on lunar dust simulants (LDS). A novel Simulant Moon Agglutinate (SMA), composed of a glassy matrix with np-Fe0, was produced and ball milled in an inert atmosphere to expose non-oxidized Fe0 surface centers and to obtain a dust with respirable particle size. Physicochemical properties, oxidative activity, and iron release in simulated body fluids were assessed on selected SMA samples. SMA were aged in air, and the kinetics of free radical generation revealed a strong redox activity that decreased with aging. After an oxidative ageing of 1 month, SMA was still active in generating free radicals, to a higher extent that other LD simulants like JSC-1A-vf, highlighting the key role of np-Fe0 in eliciting LD peculiar reactivity. In vitro tests showed that SMA caused no cell membrane damage, suggesting that LD toxicity mechanisms might involve free radicals and may differ from terrestrial toxic dust, such as quartz

Museum Pavillion

The site redevelopment involved the creation of a museum-educational centre with an experimental archaeometallurgy workshop, and the securing of some disused galleries to make them accessible for visits. The design evokes the industrial character of the site, inspired by historic structures (shelters, cranes, pulleys) while introducing geometric elements that reconnect the existing features with the surrounding natural landscape. Lightweight and dry construction solutions ensure reversible interventions, minimizing environmental impact. The museum-info point is an extension of the municipal guesthouse, featuring a room for educational activities and an exhibition path detailing the history of the mining complex. The new structure, built with dry construction and clad in metal sheeting, forms a courtyard that recalls the historic access to the Sant’Anna gallery. The large window, equipped with automatic metal brise-soleils, offers views of the Buthier stream and surrounding peaks, allowing flexible interior configurations. Interior and exterior lighting highlights the architectural geometry, turning the new building into a landmark for Ollomont

Science, Class and Reproduction. Reflections on a "Global" Marx

Relying on the perspective of a global Marx, which emphasizes the need to avoid separating the various levels of his theoretical and practical engagement with historical reality, this essay raises three key questions to Michael Heinrich’s Die Wissenschaft vom Wert. The first concerns the Marxian concept of science and its inherent connection to the class struggle. The second challenges the priority Heinrich places on the worker as a self-interested individual and poses the problem of its relation to the workers as a collective. The third addresses social reproduction, questioning the link Heinrich establishes between the historical preconditions of capital and its fully developed form

Effect of temperature on the modal parameters of continuous rigid frame bridge

The temperature effect on modal parameters such as natural frequencies, mode shapes, and damping ratios is critical for precisely determining the health of a bridge. This is the first study investigating how temperature affects the modal properties of a large continuous rigid-frame bridge. The vibration experiment data was collected and analyzed 39 times within a year's maximum and minimum temperatures. The frequency has been analyzed using the Fast Fourier transform (FFT) algorithm. Mode shape and damping ratio were analyzed using MATLAB software using the covariance-driven stochastic subspace identification method (SSI-COV) and the logarithmic decrement method. Due to the unique shape of the bridge, numerical simulations were performed using Midas Civil software to validate the results. Moreover, the correlation coefficients of frequencies and damping ratios at different temperatures have been evaluated by this observation, which will assist in identifying the large continuous rigid frame bridge's health at various temperatures

Elucidating the interplay between structure and electrochemical behavior in lignin-based polymer electrolytes for potassium batteries

Potassium batteries are very appealing for stationary applications and domestic use, offering a promising alternative to lithium-ion systems. To improve their safety and environmental impact, gel polymer electrolytes (GPEs) based on bioderived materials can be employed. In this work, a series of biobased membranes are developed by crosslinking pre-oxidized Kraft lignin as bio-based component and poly(ethylene glycol) diglycidyl ether (PEGDGE) as functional linker with 200, 500, and 1000 g mol-1 molecular weight. The influence of PEGDGE chain length on the physicochemical properties and electrochemical performance of GPEs for potassium batteries is investigated. These membranes exhibit thermal stability above 240°C and tunable glass transition temperatures depending on the PEGDGE molecular weight. Their mechanical properties are determined by rheology measurements in dry and swollen states, evidencing a slight decrease of elastic modulus (G′) by increasing PEGDGE chain length. An approximately one-order-of-magnitude lower G′ value is observed in swollen membranes versus their dry counterpart. Upon successful activation of the lignin-based membranes by swelling in the liquid electrolyte embedding potassium salts, these GPEs are tested in potassium metal cell prototypes. These systems exhibit ionic conductivity of ~10-3 S cm-1 at ambient temperature. Interestingly, battery devices equipped with the GPE based on PEGDGE 1000 g mol−1 withstand current densities as high as 1.5 mA cm-2 during operation. Moreover, the same devices reach specific capacities of 130 mAh g-1 at 0.05 A g-1 in the first 100 cycles and long-term operation for over 2500 cycles, representing outstanding achievements as bio-sourced systems for potassium batteries

Blockade of YAP Mechanoactivation Prevents Neointima Formation and Adverse Remodeling in Arterialized Vein Grafts

Background: Bypass surgery using saphenous vein (SV) grafts is commonly performed to revascularize the ischemic heart and lower limbs. These interventions have limited success due to adverse remodeling caused by overproliferation of smooth muscle cells in the intima layer, leading to progressive bypass stenosis. We previously showed that cyclic strain deriving from exposure to coronary flow induces the expression of the matricellular protein thrombospondin-1 in the human SV, promoting activation of progenitor cells normally residing in the adventitia. Methods: We analyzed the data of an RNA-sequencing profiling of human SV progenitors subjected to uniaxial strain we previously performed by. Experiments in cell culture, ex vivo, and in vivo vein arterialization models were performed to substantiate findings with particular reference to the role of mechanically activated transcription factors. Validation was performed in vitro and in ex vivo/in vivo models of vein graft disease. Results: Results of bioinformatic assessment of the RNA-sequencing data indicated Yes-associated protein (YAP) as a possible mechanically regulated effector in pathologic evolution of SV progenitors. Inhibition of YAP by verteprofin-a drug that abolishes the interaction of YAP with Tea Domain DNA-binding proteins-reduced the expression of pathologic markers in vitro and reduced intima hyperplasia in vivo. Conclusions: Our results reveal that desensitizing the SV-resident cells to mechanoactivation of YAP is feasible to reduce the graft disease progression

Vector flows that compute the capacity of discrete memoryless channels

One of the fundamental problems of information theory, since its foundation by C. Shannon, has been the computation of the capacity of a discrete memoryless channel, a quantity expressing the maximum rate at which information can travel through the channel. In this paper, we investigate the properties of a novel approach to computing the capacity, based on a continuous-time dynamical system. Interestingly, the proposed dynamical system can be regarded as a continuous-time version of the classical Blahut-Arimoto algorithm, and we can prove that the former shares with the latter an exponential rate of convergence if certain conditions are met. Moreover, a circuit design is presented to implement the dynamics, hence enabling analog computation to estimate the capacity

Resilience-based assessment of seismic risk by investigating the socioeconomic and structural earthquake engineering factors

Various impacts of earthquakes in different countries with distinct social and economic conditions (SEC) indicate that seismic risk is affected by SEC. It is also well accepted that seismic risk depends, through the quality of structures in built environments, on structural earthquake engineering (SEE) actions. The consequences of earthquakes correspondingly affect SEC and the status of SEE, at least by attracting attention to engineering solutions that aim to overcome the continuing challenge of safety against earthquakes. SEC and SEE are therefore two fundamental dimensions of sustainable seismic resilience, which is the key earthquake disaster risk reduction strategy. This paper explores resilience-related interactions between SEC and SEE to help humanity more effectively cope with the earthquake challenge. Ten earthquake-prone countries are selected as case studies. SEC are statistically evaluated based on some related criteria, including migration rate and monetary flow. The status of SEE is thoroughly investigated by considering both direct and indirect factors. The application of seismic isolation, the well-known SEE solution, and completeness of open street map projects are the studied direct factors. Death tolls and economic losses are considered as the indirect factors relating to inappropriate and inadequate preparedness against earthquakes. Interactions between SEC and SEE are discussed through detailed comparisons of the studied measures, and seismic risk is assessed based on resilience. It is shown that disaster risk reduction essentially requires economic support by the government and this can occur if the society is aware of the need for implementing effective SEE techniques in civil engineering practice