Kinds Of Patches Research Articles

On a supersonic-sonic patch arising from the two-dimensional Riemann problem of the compressible Euler equations

We are interested in the two-dimensional four-constant Riemann problem to the isentropic compressible Euler equations. In terms of the self-similar variables, the governing system is of nonlinear mixed-type and the solution configuration typically contains transonic and small-scale structures. We construct a supersonic-sonic patch along a pseudo-streamline from the supersonic part to a sonic point. This kind of patch appears frequently in the two-dimensional Riemann problem and is a building block for constructing a global solution. To overcome the difficulty caused by the sonic degeneracy, we apply the characteristic decomposition technique to handle the problem in a partial hodograph plane. We establish a regular supersonic solution for the original problem by showing the global one-to-one property of the partial hodograph transformation. The uniform regularity of the solution and the regularity of an associated sonic curve are also discussed.

Cyclic inelastic behaviour of a bonded patch repair system used for pipes with through-wall corrosion damage

Repairs of through-wall corrosion damage in pipes conveying liquids using bonded metallic patches are becoming common in the oil and gas industry. Usually, this kind of patch is used in association with a composite sleeve, and it is essential to assure that the repair wońt leak. The use of bonded metallic patches associated with the composite sleeve is not forbidden in the standards for the design of composite repair systems (such as ASME PCC-2 and ISO 24817). However, they do not address this very frequent practice adopted in industry. Since the patch is responsible for sustaining most of the pressure of the repair, it becomes necessary to further understand its behaviour. This paper investigates the cyclic inelastic behaviour of a metal patch/adhesive system and its effect on the failure pressure. Hydrostatic tests were performed regarding how pressure variations can generate cyclic inelastic strains in the adhesive layer that bonds the metal patch to the pipe, and how this cyclic loading–unloading process ultimately affects the failure pressure. The failure pressure in monotonic burst tests can be reasonably modelled using basic concepts of linear elastic fracture mechanics. Although the assumption of a brittle-elastic behaviour of the repair system seems adequate in the case of monotonic loading, it is not in the case of cyclic tests with high pressure amplitudes. Repairs in steel pipes under pressure with a 25 mm diameter hole failed after a very small number of cycles with pressure amplitude of 80% of the average failure pressure obtained in monotonic burst tests. To help understanding the behaviour of the system, single lap joints were studied. The patch and pipe are not subjected to significant permanent deformations, while the adhesive layer has an inelastic behaviour. Results show that the lap joints present a rate-dependent behaviour in tensile tests and may present highly different cyclic responses which are quite sensitive to very small perturbations in the manufacturing process.

HIV-1 immature virion network and icosahedral capsids self-assembly with patchy spheres

The self-assembling process of a simple 3D molecular model that reproduces the hexagonal lattice that HIV-1 has in its immature stage is presented. The system is made of two overlapped repulsive spheres as a building block, both spheres are decorated with attractive patches simulating the main HIV-1 Gag interactions. If the overlapped spheres have the same diameter size, a flat lattice is assembled, while a curvature is induced in the resulting lattice when different diameters are used. Thus, the importance of this model lies on the fact that only by changing the overlapped spheres diameters it is possible to form icosahedral capsids according to the Kaspar and Klug model, known as T = 1, T = 3 and T = 4 without the use of any scaffold, such as the surface of a sphere. Only one molecular species is used to assemble hexagons and pentagons. WCA potential is used for repulsive particles and LJ for the attractive ones. Only two kinds of patches are needed to form a capsid. Two patches to form pairs, which form hexagons and pentagons, and the one that forms triplets, which connects the polygons together. These interactions are based on previous reports of the HIV-1 Gag protein.

Anticancer effect of locally applicable aptamer-conjugated gemcitabine-loaded atelocollagen patch in pancreatic cancer patient-derived xenograft models.

We investigated the anticancer effect of the aptamer‐conjugated gemcitabine‐loaded atelocollagen patch in a pancreatic cancer patient–derived xenograft (PDX) model to propose a future potential adjuvant surgical strategy during curative pancreatic resection for pancreatic cancer. A pancreatic cancer PDX model was established. Animals were grouped randomly into a no‐treatment control group; treatment group treated with intraperitoneal gemcitabine injection (IP‐GEM) or aptamer‐conjugated gemcitabine (APT:GEM); and transplant with three kinds of patches: atelocollagen‐aptamer‐gemcitabine (patch I), atelocollagen‐inactive aptamer‐gemcitabine (patch II), and atelocollagen‐gemcitabine (patch III). Tumor volumes and response were evaluated based on histological analysis by H&E staining and Immunohistochemistry (IHC) was performed. Anticancer therapy–related toxicity was evaluated by hematologic findings. The patch I group showed the most significant reduction of tumor growth rate, compared with the no‐treatment group (p < 0.05). However, other treatment groups were not found to show significant reduction in tumor growth rate (0.05 < p < 0.1). There was no microscopic evidence suggesting potential toxicity, such as inflammation, nor necrotic changes in liver, lung, kidney, and spleen tissue. In addition, no leukopenia, anemia, or neutropenia was observed in the patch I group. This implantable aptamer‐drug conjugate system is thought to be a new surgical strategy to augment the oncologic significance of margin‐negative resection in treating pancreatic cancer in near future.

Propagation Phenomena in Periodic Patchy Landscapes with Interface Conditions

This paper is concerned with a model for the dynamics of a single species in a one-dimensional heterogeneous environment. The environment consists of two kinds of patches, which are periodically alternately arranged along the spatial axis. We first establish the well-posedness for the Cauchy problem. Next, we give existence and uniqueness results for the positive steady state and we analyze the long-time behavior of the solutions to the evolution problem. Afterwards, based on dynamical systems methods, we investigate the spreading properties and the existence of pulsating traveling waves in the positive and negative directions. It is shown that the asymptotic spreading speed, \(c^*\), exists and coincides with the minimal wave speed of pulsating traveling waves in positive and negative directions. In particular, we give a variational formula for \(c^*\) by using the principal eigenvalues of certain linear periodic eigenvalue problems.

Ovalbumin and cholera toxin delivery to buccal mucus for immunization using microneedles and comparison of immunological response to transmucosal delivery

The oral mucosa is an effective site for vaccination. However, for oral mucosal vaccines, delivery of the right dose of vaccine is not possible due to the water-rich environment. In this study, the buccal mucosa, which is easy to access using a microneedle array in the oral cavity, was selected as the administration site. The immune responses to the use of microneedles to conventional transmucosal delivery were compared. In addition, the adjuvant effect of the addition of cholera toxin (CT) to the drug formulation was observed. Two kinds of patches were prepared: (1) Ovalbumin (OVA) was dip coated only on the tips of microneedles (C-OVA-MN) and (2) OVA was coated on the surface of a flat disk patch substrate without microneedles (C-OVA-D). The drug delivery properties of C-OVA-MN and C-OVA-D were investigated using fluorescent-labeled OVA (OVA/FITC). Each patch was administered to mice twice, 2weeks apart, and then antibody titers were measured. A microneedle patch can deliver vaccine into the epithelium of the buccal mucosa in a short period of time compared to transmucosal delivery. A microneedle system of C-OVA-MN showed a high serum IgG titer. In addition, CT triggered CD8+ and CD4+ T cell-mediated immune responses. Through this study, we present the possibility of a new method of vaccination to the buccal mucosa using microneedles and CT adjuvant. Illustration of delivery of vaccine to the oral mucosal epithelium using a microneedle patch: Ovalbumin (OVA)-coated microneedle (C-OVA-MN) consists of tip, step, and coating formulation. Microneedle patch coated with OVA formulation is targeting buccal mucosa, which is easy to access in the oral cavity. OVA is delivered to the buccal epithelium precisely using a microneedle patch, and OVA is delivered by transmucosal route using a disk patch.

Diagnosis of Coronary Heart Disease by Optical Coherence Tomography Using Random Walk Algorithm

Objective: The objective is to study the diagnosis of coronary heart disease by optical coherence tomography based on random walk algorithm, so as to assist doctors in diagnosing coronary heart disease. Method: K-means algorithm combined with mathematical morphology provides seed points for random walk algorithm, and realizes semi-automatic segmentation of different kinds of patches. Secondly, by adding the space distance term based on the distance between the edge and the seed point in the weight function, the random walk algorithm is improved, which can make the weak edge patch area not be segmented too much. Results: the results were obtained by comparing the traditional random walk method and the literature method. The segmentation accuracy of this method is higher, and it is more convenient to use. Moreover, the average segmentation time of single image is not more than 5 s, which can basically meet the real-time needs of clinical diagnosis. Conclusion: Experiments show that the method proposed in this study is easy to use, with high segmentation accuracy, and to some extent, it can provide the clinician with plaque area information, improve the speed of reading films, and assist doctors in diagnosing coronary heart disease. In this study, the random walk algorithm is improved to get a better segmentation algorithm than other methods.

Burrowing and Anti-Predator Requirements Determine the Microhabitat Selection of Himalayan Marmot in Zoige Wetland.

To satisfy their requirements for food and safety, animals need certain habitats to live. Marmots generally select habitats with certain elevation, land surface temperature, soil and vegetation type, and certain mountain slope and aspect; however, what habitats are needed at relatively smaller scales are poorly known. The Himalayan marmot (Marmota himalayana) is distributed mainly on the Qinghai-Tibet Plateau, a region exhibiting diversified topographic features, and the Zoige wetland in the northeast part of the plateau is also the home of the Himalayan marmot. The region is famous for its plateau peat bog, and the suitable habitats for Himalayan marmots are patchily distributed in the wetland. To investigate what kinds of patches are preferred by the marmot in this wetland ecosystem, we measured and compared the soil and vegetation characteristics of used and unused patches. We found that unlike factors governing the habitat selection at macroscales, patches characterized by flat ground and low soil moisture content, with medium vegetation standing height and low vegetation density, are selected in the Zoige wetland. Patches of this kind are selected to meet the marmots' requirements for burrow construction and predator avoidance in such a wetland ecosystem. Together with previous studies on habitat selection of the marmot species at macroscales, we showed that to explore how the animals survive in an environment, it is important to conduct the analysis at multiple scales.

Study in circular auxetic structures for efficiency enhancement in piezoelectric vibration energy harvesting

Piezoelectric (PZT) components are one of the most popular elements in vibration sensing and also energy harvesting. They are very well established, cost effective and available in different geometries however there are still several challenges in their application particularly in vibration energy harvesting. They are normally narrow-band elements and work in high-frequency range. Their efficiency and power extraction density are also generally low compared with different electromagnetic techniques. Auxetic structures are proposed here to enhance efficiency of the piezoelectric circular patches in vibration energy harvesting. These kinds of patches namely PZT buzzers are inexpensive (less than 10 USD) elements and easily available. Two novel circular auxetic substrates are proposed to improve power extraction capacity of the conventional piezoelectric buzzers. Negative Poison’s ratio of the proposed meta-structure helps in efficiency enhancement. The concept is introduced, analyzed and verified through the finite element modeling and experimental testing. The idea is proved to work by comparing the harvested electrical power in the auxetic design against the conventional plain system. A parametric study is then carried out and effects of important electrical and geometrical parameters as well as the material property on the power extraction efficiency are assessed to arrive at optimum parameters. It is shown that by employing the auxetic design, a remarkable improvement in the harvested power is achievable. It is shown that for the two proposed auxetic designs, at the resonance frequency, we could reach to 10.2 and 13.3 magnification factor with respect to the plain energy harvester. Another important feature is that the resonant frequency in these new designs is very much lower than the conventional resonators. Results of this study can open a new path to application of inexpensive PZT buzzers in large-scale vibration energy harvesting.

Analysis of Urban Green Space Landscape Pattern in Suzhou

Based on the landscape ecological methods, GIS software and aerial images of 2018a, this paper studies the spatial pattern of urban green landscape of Suzhou via landscape ecological theory. The green landscape was consists of several kinds of patches according to the size. Landscape ecological indexes such as the number of patches, landscape fragmentation, and landscape separation were selected to study the landscape pattern of green space in the main urban area of Suzhou. The results show that the biggest green area is in Wuzhong District, the minimum is Gusu District; the green landscape fragmentation of Gusu Districtis is the highest, but the lowest is in Wuzhong District; the landscape separation degree is the largest in Wuzhong District, and the industrial park is the smallest. Comprehensive analysis shows that the landscape pattern of green space in Wuzhong District is more desirable. Finally, some suggestions are given on how to optimize the green space construction in Suzhou.

Hybrid image denoising based on region division

This paper proposes an efficient hybrid framework for image denoising, in which the advantages of different denoising methods are effectively incorporated by using the region prior knowledge. In detail, the input noisy image is first divided into a large number of overlapping patches followed by extraction of Speed Up Robust Feature (SURF), and then the noisy patches are classified into two categories based on Twin Support Vector Machine (TWSVM). The texture patches are enhanced via Gradient Histogram Preservation (GHP) while flat patches can be re-established using Block Matching Three-Dimensional Filtering (BM3D). Finally, the re-established images can be acquired by fusing the processing results of the two kinds of patches. To evaluate the effectiveness of the presented method, we conduct experiments on standard image datasets and compare the performance with other outstanding denoising approaches. Experimental results show that the presented method achieves better results, especially in containing textures and edges compared with existing image denoising methods.

Hybrid image denoising based on region division

This paper proposes an efficient hybrid framework for image denoising, in which the advantages of different denoising methods are effectively incorporated by using the region prior knowledge. In detail, the input noisy image is first divided into a large number of overlapping patches followed by extraction of Speed Up Robust Feature (SURF), and then the noisy patches are classified into two categories based on Twin Support Vector Machine (TWSVM). The texture patches are enhanced via Gradient Histogram Preservation (GHP) while flat patches can be re-established using Block Matching Three-Dimensional Filtering (BM3D). Finally, the re-established images can be acquired by fusing the processing results of the two kinds of patches. To evaluate the effectiveness of the presented method, we conduct experiments on standard image datasets and compare the performance with other outstanding denoising approaches. Experimental results show that the presented method achieves better results, especially in containing textures and edges compared with existing image denoising methods.

Patchy Templated Synthesis of Macroporous Colloidal Hollow Spheres and Their Application as Catalytic Microreactors.

Porous colloidal hollow spheres have been applied to diversified fields over the past few decades. However, developing simple and efficient methods to prepare such porous hollow spheres with macro pores remains a challenge. To address this problem, we present a patchy templated synthesis route, which can be used to prepare such colloidal hollow spheres that have macro pores through the shells. This was achieved by using patchy poly(styrene-co-sodium styrenesulfonate) spheres as the template and poly(allylamine hydrochloride) as binding molecules. SiO2 can site-selectively only grow on one kind of patch, resulting in the formation of porous hollow spheres. The pore sizes can be tuned from ∼50 to 400 nm. The resulting porous hollow spheres have a Janus character so that Au nanoparticles can only be attached to the interior surfaces in situ, which can be used as catalytic microreactors and show the catalytic performance of pore size dependence.

SQL: Superpixels via quaternary labeling

This paper formulates superpixel segmentation as a pixel labeling problem and proposes a quaternary labeling algorithm to generate superpixel lattice. It is achieved by seaming overlapped patches regularly placed on the image plane. Patch seaming is formulated as a pixel labeling problem, where each label indexes one patch. Once the optimal seaming is completed, all pixels covered by one retained patch constitute one superpixel. Further, four kinds of patches are distinguished and assembled into four layers correspondingly, and the patch indexes are mapped to the quaternary layer indexes. It significantly reduces the number of labels and greatly improves labelling efficiency. Furthermore, an objective function is developed to achieve optimal segmentation. Lattice structure is guaranteed by fixing patch centers to be superpixel centers, compact superpixels are assured by horizontal and vertical constraints enforced on the smooth terms, and coherent superpixels are achieved by iteratively refining the data terms. Extensive experiments on BSDS data set demonstrate that SQL algorithm significantly improves labeling efficiency, outperforms the other superpixel lattice methods, and is competitive with state-of-the-art methods without lattice guarantee. Superpixel lattice allows contextual relationships among superpixels to be easily modeled by either MRFs or CNN.

Thermographic Investigation of Bronze Artefacts: Characterization of Structure Elements and Casting Faults in Masterpieces of the Bronze Statuary of Rome

In this paper, the thermographic results obtained by studying some masterpieces of the bronze statuary of Rome are presented. More specifically, a quantitative approach has been adopted in the investigation of the Capitoline She Wolf, hosted in the Musei Capitolini, and of the Boxer at Rest and the Hellenistic Prince belonging to the collection of the Museo Nazionale Romano. The obtained results provided data useful to characterize the properties of the bronze alloy and several subsurface features of the statue, such as casting faults and patches. In particular, the interface between different kind of patches and the main body of the statue has been investigated in order to determine the way they were applied. Moreover, the thermal diffusivity of the alloy of the Capitoline She Wolf has been evaluated and quantitative investigations have been carried out in order to determine the depth of some features, such as the cavities originating from air bubbles in the casting melt.

Analysis of the Failure of Bonded Interface between Aluminium Skin and FRP Patch Using Cohesive Zone Model

A single-sided patch of unidirectional carbon fibre-reinforced polymer composite was bonded on a 1.0 mm-thick skin of aluminium alloy 6061-T6 with a centre crack of 25 mm length. Two kinds of patches were studied: (1) 1-ply patch and (2) 2-ply patch. Experiments were conducted to determine the strength of 1-ply patch. It was then simulated using finite element analysis employing a cohesive zone model in ANSYS 15.0. When the repaired specimen was subjected to a quasistatic load, the patch started separating at the crack edge due to the combined action of high peel and the shear stresses at the interface. The rate of separation was slow initially, but grew rapidly at high loads. Separation cracks were also initiated at the leading edges at high loads, leading to catastrophic failure of the specimen. The numerically obtained failure load was compared with that obtained through the experiments, and the effectiveness of using the cohesive zone model for simulating the interface failure was established. The numerical analysis was then applied to predict the failure behaviour of 2-ply patches. The strengths of the 1-ply patch and 2-ply patch for different patch lengths were compared. The strength of 2-ply patch was found to be considerably higher over that of 1-ply patch for short-length patches. However, the difference diminished with the increasing patch length.

Preparation of CS/PVA Nanofibrous Membrane with Tunable Mechanical Properties for Tympanic Member Repair

The wound healing for tympanic membrane (TM) perforations is one of the most common clinic treatment. New designs of biomaterials, and lately tissue-engineered composites and grafts, have been applied for the management of TM perforation. In this work, a series of chitosan (CS)/polyvinyl alcohol (PVA) nanofibrous films have been fabricated as a kind of patch for repairing TM perforation. The scaffolds were crosslinked by glutaraldehyde solution to prevent them from being dissolved in the culture medium. The morphology of nanofibers from different precursors has been observed by using scanning electron microscopy (SEM). And the crosslinked films have been characterized by SEM and Fourier transform infrared spectroscopy for confirming its morphology and chemical structure. We found the films with crosslinking showed stronger tensile strength and modulus compared to the uncrosslinked one. And the mechanical properties could be tuned by the crosslinking time. In addition, after crosslinked, the films showed good thermostability and water-resistance, characterized by thermo gravimetric analyzer and contact angle meter. The cell viability studies with human umbilical vein endothelial cells, fibroblasts and mesenchymal stem cells demonstrated that the nanofibrous scaffolds formed by electrospinning process had no side effects for cell proliferation. However, a better way of crosslinking CS/PVA films needs to be further studied.

Novel descriptors for geometrical 3D face analysis

3D face was recently investigated for various applications, including biometrics and diagnosis. Describing facial surface, i.e. how it bends and which kinds of patches is composed by, is the aim of studies of Face Analysis, whose ultimate goal is to identify which features could be extracted from three-dimensional faces depending on the application. In this study, we propose 105 novel geometrical descriptors for Face Analysis. They are generated by composing primary geometrical descriptors such as mean, Gaussian, principal curvatures, shape index, curvedness, and the coefficients of the fundamental forms, and by applying standard functions such as sine, cosine, and logarithm to them. The new descriptors were mapped on 217 facial depth maps and analysed in terms of descriptiveness of facial shape and exploitability for localizing landmark points. Automatic landmark extraction stands as the final aim of this analysis. Results showed that some newly generated descriptors were sounder than the primary ones, meaning that their local behaviours in correspondence to a landmark position is thoroughly specific and can be registered with high similarity on every face of our dataset.

Do farmers use, and imitate, self-organizing resource-concentration mechanisms driven by non-human engineers in constraining environments? Biocultural landscapes and biomimicry at the ecosystem level

In a wide range of environments —but which all have in common the scarcity of some key resource that is crucial for life— there have emerged ecosystems that show remarkably regular spatial patterns in the distribution of vegetation, in topography, or both. These patterns have been shown to result from the activities of organisms that can be classed as “ecosystem engineers.” In these constraining environments, “engineer” organisms, acting in concert with physical mechanisms, convert an initially homogeneous landscape into a landscape composed of two kinds of patches, one kind in which the crucial resource is concentrated, the other kind in which the crucial resource is depleted. Thus, in environments where a crucial resource is generally scarce, engineer organisms create patches of habitat in which the resource is relatively abundant. This allows organisms to persist in environments that would otherwise be marginal (or worse) for their survival. The process by which this occurs is termed “spatial self-organization” and the phenomenon is called “self-organized patchiness.” In some of the environments where strikingly patterned, self-organized ecosystems occur, farmers construct cultural landscapes that are remarkably similar to the constructions of the “engineer” organisms. This resemblance between artefacts made by humans and constructions made by non-human living beings raises numerous questions. Does the resemblance reflect independent convergence on similar adaptive solutions to constraining environments, or do human and non-human engineers interact in one or more ways? The objective of this presentation is to explore these questions.

Treatment of large corneal perforations with acellular multilayer of corneal stromal lenticules harvested from femtosecond laser lenticule extraction

To describe a novel surgical technique for the treatment of large corneal perforations by using acellular multilayer of corneal stromal lenticules. Prospective study. The acellular tissue used for the repair was harvested from myopic patients during the femtosecond laser (FS) refractive surgery. Informed consent, blood test and donor eligibility were obtained in each case. Three or four layers of lenticules were stacked up and stored at -80°C in pure sterile glycerin. The diameter is 6.0 to 6.5 mm and central thickness was 300 to 400 µm. If the diameter of the corneal ulcer perforation was larger than 3 mm and corneal grafts were not available, we used this kind of patches to seal the perforations. It was a retrospective case series study. Five cases of corneal ulcer perforation were enrolled in this study. One was neuropathic keratitis, one was atopic keratoconjunctivitis, and the other three were fungal keratitis. Acellular multilayer of stromal lenticules were used in these cases for emergent therapy. The sealing of the perforation and the re-establishment of the anterior chamber were achieved successfully in all the cases. For the pericentral perforations, visual recovery was achieved. And efficient palliative management was done for the central perforations. The reported technique seems to represent a good alternative emergency procedure for the management of large corneal perforations. It is a very useful method for Chinese hospitals where the shortage of cornea donors is a very serious problem and the amount of FS surgeries are increasing.