Characterising the effects of wind-driven rain on the thermophysical performance of cavity walls by means of a Bayesian framework

Cavity wall is one of the most common construction types in temperate maritime climates, including the UK. However, water penetration may lead to damp within the structure, freeze-thaw damage at the outer surface and a reduction in thermal resistance. The magnitude of wetting effects on the energy performance of cavity walls is still unclear, with potentially significant implications for climate-change-mitigation strategies. This paper investigates the thermophysical performance of uninsulated and insulated cavity walls and its degradation as the element is wettened. Experiments were performed in a hygrothermal laboratory where two cavity-wall specimens (one of which coated with external waterproofing treatment) were tested under a high wind-driven rain exposure. Changes in the thermophysical performance between dry and wet conditions were evaluated through U-value testing and Bayesian inference. Substantial U-value increase was observed for wet uninsulated specimens (compared to dry conditions); conversely, closer U-value ranges were obtained when insulated with EPS grey beads. Moreover, latent-heat effects through the external masonry leaf of the untreated specimen were predicted by the Bayesian framework. Results suggest a negligible efficacy of waterproofing surface treatments as strategies for the reduction of heat transfer within the element, and possible effects of these agents on the evaporative and drying process.

The Multi-slice Spiral Computed Tomography (MSCT) Features of Thin-Walled Cystic Lung Cancer with Ground Glass Opacity

Background: Lung cancer is the leading cause of cancer-related mortality worldwide. Thin-walled cystic lung cancer with ground glas s opacity (GGO) is a type of lung carcinoma with specific computed tomography (CT) features. Objectives: To investigate the imaging features of multi-slice spiral computed tomography (MSCT) of GGO and to improve the imaging diagnosis of this type of lung cancer. Patients and Methods: The clinical data of 24 patients with pathologically confirmed thin-walled cystic lung cancer with GGO were retrospectively analyzed in this study. The imaging features of preoperative MSCT, including vascular convergence, burr signs, pleural depression signs, lobulation signs, thickness and uniformity of the cavity wall, partitive membranes, and position of the ground-glass cavity, were examined. The relationship between the imaging features and postoperative pathological findings of lung carcinoma were also explored. Results: Most of the lesions (75.0%) were located in the upper lobe of the lungs. The size range of the cavity was 5.8 - 28.1 mm, with a mean of 13.6 ± 7.2 mm. Fifteen patients (62.5%) had a cavity wall thickness < 2 mm, 6 (25.0%) patients had a cavity wall thickness in the range of 2 - 3 mm, and 3 (12.5%) patients had a cavity wall thickness of about 3 - 4 mm. A uniform cavity wall was found in 10 (41.7%) cases, while a non-uniform cavity wall was observed in 14 (58.3%) cases. Eleven patients showed pure GGO (45.8%), while 13 patients showed mixed GGO (54.2%). Besides, nine patients (37.5%) showed lobular signs, 12 (50.0%) patients showed spicule signs, and 6 (28.6%) patients showed vascular convergence signs. Twelve patients (50.0%) had signs of pleural indentation, while 14 (66.7%) patients showed thick or thin small blood vessel opacity or fine partitive membranes. Twenty-three patients were diagnosed with lung adenocarcinoma, while one patients was diagnosed with mixed adenosquamous carcinoma. Conclusion: Thin-walled cystic lung cancer with GGO is a rare clinical phenomenon. The imaging features of this type of lung cancer on MSCT are consistent with the characteristics of lung cancers.

Assessment of the Parameters of a Shock Wave on the Wall of an Explosion Cavity with the Refraction of a Detonation Wave of Emulsion Explosives

At present, studying the parameters of shock waves at pressures up to 20 GPa entails a number of practical difficulties. In order to describe the propagation of shock waves, their initial parameters on the wall of the explosion cavity need to be known. With the determination of initial parameters, pressures in the near zone of the explosion can be calculated, and the choice of explosives can be substantiated. Therefore, developing a method for estimating shock wave parameters on an explosion cavity wall during the refraction of a detonation wave is an important problem in blast mining. This article proposes a method based on the theory of breakdown of an arbitrary discontinuity (the Riemann problem) to determine the shock wave parameters on the wall of the explosion cavity. Two possible variants of detonation wave refraction on the explosion cavity wall are described. This manuscript compares the parameters on the explosion cavity wall when using emulsion explosives with those obtained using cheap granular ANFO explosives. The detonative decomposition of emulsion explosives is also considered, and an equation of state for gaseous explosion products is proposed, which enables the estimation of detonation parameters while accounting for the incompressible volume of molecules (covolume) at the Chapman–Jouguet point.

The Mechanism Switching the Osteoclast From Short to Long Duration Bone Resorption

The current models of osteoclastic bone resorption focus on immobile osteoclasts sitting on the bone surface and drilling a pit into the bone matrix. It recently appeared that many osteoclasts also enlarge their pit by moving across the bone surface while resorbing. Drilling a pit thus represents only the start of a resorption event of much larger amplitude. This prolonged resorption activity significantly contributes to pathological bone destruction, but the mechanism whereby the osteoclast engages in this process does not have an answer within the standard bone resorption models. Herein, we review observations that lead to envision how prolonged resorption is possible through simultaneous resorption and migration. According to the standard pit model, the “sealing zone” which surrounds the ruffled border (i.e., the actual resorption apparatus), “anchors” the ruffled border against the bone surface to be resorbed. Herein, we highlight that continuation of resorption demands that the sealing zone “glides” inside the cavity. Thereby, the sealing zone emerges as the structure responsible for orienting and displacing the ruffled border, e.g., directing resorption against the cavity wall. Importantly, sealing zone displacement stringently requires thorough collagen removal from the cavity wall - which renders strong cathepsin K collagenolysis indispensable for engagement of osteoclasts in cavity-enlargement. Furthermore, the sealing zone is associated with generation of new ruffled border at the leading edge, thereby allowing the ruffled border to move ahead. The sealing zone and ruffled border displacements are coordinated with the migration of the cell body, shown to be under control of lamellipodia at the leading edge and of the release of resorption products at the rear. We propose that bone resorption demands more attention to osteoclastic models integrating resorption and migration activities into just one cell phenotype.

Full‐scale shake‐table tests on two unreinforced masonry cavity‐wall buildings: effect of an innovative timber retrofit

Two full-scale building specimens were tested on the shake-table at the EUCENTRE Foundation laboratories in Pavia (Italy), to assess the effectiveness of an innovative timber retrofit solution, within a comprehensive research campaign on the seismic vulnerability of existing Dutch unreinforced masonry structures. The buildings represented the end-unit of a two-storey terraced house typical of the North-Eastern Netherlands, a region affected by induced seismicity over the last few decades. This building typology is particularly vulnerable to earthquake excitation due to lack of seismic details and irregular distribution of large openings in masonry walls. Both specimens were built with the same geometry. Their structural system consisted of cavity walls, with interior load-bearing calcium-silicate leaf and exterior clay veneer, and included a first-floor reinforced concrete slab, a second-floor timber framing, and a roof timber structure supported by masonry gables. A timber retrofit was designed and installed inside the second specimen, providing an innovative sustainable, light-weight, reversible, and cost-effective technique, which could be extensively applied to actual buildings. Timber frames were connected to the interior surface of the masonry walls and completed by oriented strands boards nailed to them. The second-floor timber diaphragm was stiffened and strengthened by a layer of oriented-strand boards, nailed to the existing joists and to additional blocking elements through the existing planks. These interventions resulted also in improved wall-to-diaphragm connections with the inner leaf at both floors, while steel ties were added between the cavity-wall leaves. The application of the retrofit system favored a global response of the building with increased lateral capacities of the masonry walls. This paper describes in detail the bare and retrofitted specimens, compares the experimental results obtained through similar incremental dynamic shake-table test protocols up to near-collapse conditions, and identifies damage states and damage limits associated with displacements and deformations.

Particle Coherent Structures in Confined Oscillatory Switching Centrifugation

A small spherical rigid particle in a cylindrical cavity is considered. The harmonic rotation of the cavity wall drives the background flow characterized by the Strouhal number Str, assumed as the first parameter of our investigation. The particle immersed in the flow (assumed Stokesian) has a Stokes number St=1 and a particle-to-fluid density ratio ϱ which is assumed as the second parameter of this study. Building on the theoretical understanding of the recently discovered oscillatory switching centrifugation for inertial particles in unbounded flows, we investigate the effect of a confinement. For the first time we study how the presence of a wall affects the particle trajectory in oscillatory switching centrifugation dynamics. The emergence of two qualitatively different particle attractors is characterized for particles centrifuged towards the cavity wall. The implication of two such classes of attractors is discussed focusing on the application to microfluidics. We propose some strategies for exploiting the confined oscillatory switching centrifugation for selective particle segregation and for the enhancement of particle interaction events.