Littérature scientifique sur le sujet « Pulling test »

The aim of the paper was to determine the influence of root systems of chosen tree species found in the Polish Flysch Carpathians on the increase of soil shear strength (root cohesion) in terms of slope stability. The paper's goal was achieved through comprehensive tests on root systems of eight relatively common in the Polish Flysch Carpathians tree species. The tests that were carried out included field work, laboratory work and analytical calculations. As part of the field work, the root area ratio (A IA) of the roots was determined using the method of profiling the walls of the trench at a distance of about 1.0 m from the tree trunk. The width of the. trenches was about 1.0 m, and their depth depended on the ground conditions and ranged from 0.6 to 1.0 m below the ground level. After preparing the walls of the trench, the profile was divided into vertical layers with a height of 0.1 m, within which root diameters were measured. Roots with diameters from 1 to 10 mm were taken into consideration in root area ratio calculations in accordance with the generally accepted methodology for this type of tests. These measurements were made in Biegnik (silver fir), Ropica Polska (silver birch, black locust) and Szymbark (silver birch, European beech, European hornbeam, silver fir, sycamore maple, Scots pine, European spruce) located near Gorlice (The Low Beskids) in areas with unplanned forest management. In case of each tested tree species the samples of roots were taken, transported to the laboratory and then saturated with water for at least one day. Before testing the samples were obtained from the water and stretched in a. tensile testing machine in order to determine their tensile strength and flexibility. In general, over 2200 root samples were tested. The results of tests on root area ratio of root systems and their tensile strength were used to determine the value of increase in shear strength of the soils, called root cohesion. To this purpose a classic Wu-Waldron calculation model was used as well as two types of bundle models, the so called static model (Fiber Bundle Model — FIRM, FBM2, FBM3) and the deformation model (Root Bundle Model— RBM1, RBM2, mRBM1) that differ in terms of the assumptions concerning the way the tensile force is distributed to the roots as well as the range of parameters taken into account during calculations. The stability analysis of 8 landslides in forest areas of Cicikowicleie and Wignickie Foothills was a form of verification of relevance of the obtained calculation results. The results of tests on root area ratio in the profile showed that, as expected, the number of roots in the soil profile and their ApIA values are very variable. It was shown that the values of the root area ratio of the tested tree species with a diameter 1-10 ram are a maximum of 0.8% close to the surface of the ground and they decrease along with the depth reaching the values at least one order of magnitude lower than close to the surface at the depth 0.5-1.0 m below the ground level. Average values of the root area ratio within the soil profile were from 0.05 to 0.13% adequately for Scots pine and European beech. The measured values of the root area ratio are relatively low in relation to the values of this parameter given in literature, which is probably connected with great cohesiveness of the soils and the fact that there were a lot of rock fragments in the soil, where the tests were carried out. Calculation results of the Gale-Grigal function indicate that a distribution of roots in the soil profile is similar for the tested species, apart from the silver fir from Bie§nik and European hornbeam. Considering the number of roots, their distribution in the soil profile and the root area ratio it appears that — considering slope stability — the root systems of European beech and black locust are the most optimal, which coincides with tests results given in literature. The results of tensile strength tests showed that the roots of the tested tree species have different tensile strength. The roots of European beech and European hornbeam had high tensile strength, whereas the roots of conifers and silver birch in deciduous trees — low. The analysis of test results also showed that the roots of the studied tree species are characterized by high variability of mechanical properties. The values Of shear strength increase are mainly related to the number and size (diameter) of the roots in the soil profile as well as their tensile strength and pullout resistance, although they can also result from the used calculation method (calculation model). The tests showed that the distribution of roots in the soil and their tensile strength are characterized by large variability, which allows the conclusion that using typical geotechnical calculations, which take into consideration the role of root systems is exposed to a high risk of overestimating their influence on the soil reinforcement. hence, while determining or assuming the increase in shear strength of soil reinforced with roots (root cohesion) for design calculations, a conservative (careful) approach that includes the most unfavourable values of this parameter should be used. Tests showed that the values of shear strength increase of the soil reinforced with roots calculated using Wu-Waldron model in extreme cases are three times higher than the values calculated using bundle models. In general, the most conservative calculation results of the shear strength increase were obtained using deformation bundle models: RBM2 (RBMw) or mRBM1. RBM2 model considers the variability of strength characteristics of soils described by Weibull survival function and in most cases gives the lowest values of the shear strength increase, which usually constitute 50% of the values of shear strength increase determined using classic Wu-Waldron model. Whereas the second model (mRBM1.) considers averaged values of roots strength parameters as well as the possibility that two main mechanism of destruction of a root bundle - rupture and pulling out - can occur at the same. time. The values of shear strength increase calculated using this model were the lowest in case of beech and hornbeam roots, which had high tensile strength. It indicates that in the surface part of the profile (down to 0.2 m below the ground level), primarily in case of deciduous trees, the main mechanism of failure of the root bundle will be pulling out. However, this model requires the knowledge of a much greater number of geometrical parameters of roots and geotechnical parameters of soil, and additionally it is very sensitive to input data. Therefore, it seems practical to use the RBM2 model to assess the influence of roots on the soil shear strength increase, and in order to obtain safe results of calculations in the surface part of the profile, the Weibull shape coefficient equal to 1.0 can be assumed. On the other hand, the Wu-Waldron model can be used for the initial assessment of the shear strength increase of soil reinforced with roots in the situation, where the deformation properties of the root system and its interaction with the soil are not considered, although the values of the shear strength increase calculated using this model should be corrected and reduced by half. Test results indicate that in terms of slope stability the root systems of beech and hornbeam have the most favourable properties - their maximum effect of soil reinforcement in the profile to the depth of 0.5 m does not usually exceed 30 kPa, and to the depth of 1 m - 20 kPa. The root systems of conifers have the least impact on the slope reinforcement, usually increasing the soil shear strength by less than 5 kPa. These values coincide to a large extent with the range of shear strength increase obtained from the direct shear test as well as results of stability analysis given in literature and carried out as part of this work. The analysis of the literature indicates that the methods of measuring tree's root systems as well as their interpretation are very different, which often limits the possibilities of comparing test results. This indicates the need to systematize this type of tests and for this purpose a root distribution model (RDM) can be used, which can be integrated with any deformation bundle model (RBM). A combination of these two calculation models allows the range of soil reinforcement around trees to be determined and this information might be used in practice, while planning bioengineering procedures in areas exposed to surface mass movements. The functionality of this solution can be increased by considering the dynamics of plant develop¬ment in the calculations. This, however, requires conducting this type of research in order to obtain more data.

Teaching, Reading, and Theorizing Caribbean Texts explores alternative approaches to Caribbean texts from transnational and multilingual perspectives. The authors query what new systems and criteria can be implemented to rethink and remodel our theoretical and pedagogical corpus and alter the lenses through which we study Caribbean texts. Pulling from the Caribbean’s global diaspora, the authors examine writers such as Roxane Gay, Esmeralda Santiago, Wilson Harris, and Gloria Anzaldúa in order to resituate the place of Caribbean texts in the classroom. Each chapter argues for a reunification of Caribbean literature studies—rather than studying this body of text only in terms of a certain aspect of its history or culture, the authors necessitate the importance of analyzing these works from a pan-Caribbean perspective. This collection discusses the ideas of transcending individual disciplines and specialties to create global theories, overcoming pedagogical challenges when bringing Caribbean texts into the classroom, and (re)reading texts with the purpose of discovering new symbols, themes, and meanings.

Obsessive-compulsive and related disorders (OCRDs) have received considerable attention over the past two decades, culminating with the inclusion of a new classification category of “Obsessive-Compulsive and Related Disorders” in the DSM-5. This group of conditions includes obsessive-compulsive disorder along with two newly minted conditions (hoarding disorder and excoriation disorder) and others previously classified as somatoform disorders (body dysmorphic disorder) and impulse control disorders (hair-pulling disorder). In addition, other conditions that are not discussed in the DSM-5 have received attention, such as misophonia and orthorexia nervosa. The implications for research on these conditions, as well as their relations with one another, are significant since their aggregation is based on putative central mechanisms with limited empirical support to date. Indeed, the past decades have seen a dramatic surge in research on OCRDs across several domains, including clinical phenomenology, assessment, and psychological therapies. With these issues in mind, this comprehensive text addresses recent advances in the field of OCRDs, highlighting psychosocial theoretical and intervention approaches. As researchers and clinicians will be increasingly focused on this topic in light of the changes to DSM-5, this book is a timely addition to the literature in guiding clinicians in advances in OCRDs that will impact their practice.

Back, now, to Ipswich in 1568 — and to a disorientingly dual narrative in which the darker side of shared creaturely vulnerability is hidden, though ever-present, beneath a story of human victory over the monstrous. As we have seen, the strong surface current running through Timothy Granger’s broadside account of the capture of twenty-seven orca concentrates its definition of monstrousness on the size of the captured creatures. Unlike other monster broadsides of its day, it is without an explicit moral: the monsters are used neither to warn against behaviors that cross culturally constructed moral boundaries nor to plead with readers to reform their lives. It is a story of human ascendency. But pulling strongly in the other direc-tion — back to sea, back to the enormity of non-human otherness and to the disturbing darkness of unspeakable human cruelty — the broadside also illustrates the extreme brutality of the men of Ipswich upon encountering their “monsters.” The orca, once finally captured, were hauled in to Ipswich wharf; the largest was tied to a tree. “Som of them,” we learn, “laye upon the wharfe .ii. dayes and a nyght before they weare dead, and yet [the men] strooke them wyth Axes & other weapons to kyll them,” even to the point of their axes breaking on the whales’ “bones hard as stones.” While Granger never remarks upon the merciless brutality he describes at length, it saturates the text. It is likely that these actions were legible as cruelty to many contemporaries, especially those who focused on the creatures as fish first and monsters second.

Covers the rise of Ronald Reagan and a more conservative, individualistic approach to government and society that would have far-reaching effects on Charlotte schools.Explores persisting obstacles to racial advancement, including shifts in job markets, housing patterns and political priorities that perpetuated income and homeownership gaps into the 1980s and 1990s, and sharpened distinctions between struggling central-city neighborhoods and increasingly prosperous suburban communities. Traces the national shift in education priorities from promoting integration to a concern with test scores and an interest in "choice," which led Charlotte's business leaders to promote a desegregation plan focused around magnet schools instead of race-based busing. Examines growing concerns about the performance of African American students in desegregated schools, and about the challenges faced by young black men in urban neighborhoods. Follows the Capacchione lawsuit, which challenged the use of race in student assignment and brought an end to Charlotte's busing plan.

The purpose of this paper is firstly to simulate the tunnel face failure in laboratory with four cases of model tests by pulling out tunnel model from a sandy ground that are without using auxiliary method nor face bolting and using face bolting with three different lengths of bolts, and secondary, to investigate the behavior of model ground using X-ray computed tomography (CT) scanner to visualize the failure zone in three dimensions. In addition to those results, a series of centrifuge model tests are conducted to confirm the results of X-ray CT test and also to discuss the ground behavior under full scale stress level. Finally, the effect of face bolting method is evaluated based on all the test results.

To evaluate the bond performance between epoxy asphalt and cement with temperature, loading rate, thermal aging, adhesive material, and its amount of oblique shear and pull-out tests were conducted using self-designed devices. The test results show that: (1) Interlayer bonding performance decreased greatly after soaking. The shear and pull-out strength of Styrene-Butadiene-Styrene (SBS) modified asphalt decrease by 75.1% and 30.3% respectively, while that of epoxy asphalt decreases by 47.4% and 30.7%; (2) Thermal aging is an important factor in interface performance degradation, the shearing and pulling strength decrease by 23.0% and 60.5% respectively; (3) As an adhesion material, epoxy asphalt is significantly better than that SBS-modified asphalt.

Abstract The use of horizontal directional drills (HDDs) is an ever-increasing pipeline installation technique. As HDDs increase, there is an increased probability for coating damage, even when coated with traditional mill or field applied abrasion resistant overcoat (ARO). This coating damage includes shear, abrasion, impact, and gouging (SAIG) (among others) and that damage may exist for the life of the pipeline due to an HDD being inaccessible for future maintenance. Ensuring the long-term quality and performance of the coating applied to pipe within an HDD is critical for the life of the asset. Current subscale tests provide a good starting point for the ability of any given coating to provide protection from obstructions within an HDD, however, those test protocols do not currently assure or quantify additional mechanical protection currently mentioned in several ASME and ISO specifications. Therefore, there remains a need for a full-scale test alternative to provide qualitative shear, abrasion, impact, and gouging data for any given coating to be used in an HDD. The developed full-scale test alternative includes several features or obstructions that are engaged against the pipe/coating while mechanically pulling the pipe through the test cage. These features were designed to replicate the loading experienced within an HDD. The result of this test helps quantify the damage experienced. This is done through several quantitative assessments including holiday detection, gouge depth measurements, and shear disbondment. These results are then benchmarked against several commonly used mill applied coatings.

Abstract A continuing problem with coatings applied to sharp edges of a structure is the corrosion that often develops at the apex of the edge. The conventional wisdom is that the reduction of film thickness, due to coating pulling away at the edge during the curing of the coating, is the primary cause for the onset of corrosion. This theory, however, is not necessarily correct, both from a mechanistic and practical point of view. This discussion paper will present the conventional viewpoint of what is called “edge retention” or “edge coverage” and why it is insufficient in describing corrosion occurrence at an edge. Also discussed is how the current test methods provide non-relevant data to edge coverage observations. A different mechanism of the causation of corrosion at an edge is presented as well as an alternative method for evaluating the effect of edge coverage on corrosion of the system.

<p>An innovative concept design of a “carbon-neutral, easy-to-dismantle beam-column connection” was previously proposed for an environmentally friendly construction. Full-scale test and three-di- mensional finite element (3D-FE) analysis had been conducted to investigate how the so-called Carbon Minimized Dismantle Connection (CNDC) would behave. Accordingly, the CNDC met the stiffness for the rotation angle of moment frame similarly as a conventional beam-column connec- tion. However, in terms of energy dissipation, it showed relatively low performance due to pinching of moment-rotation hysteresis. Numerical modeling showed local bulging-and-dimpling of column face due to the pulling of shear tab by the beam. Hence, an improvement study on the design and configuration of the CNDC by 3D-FE analysis was carried out. Numerically, the new design of the CNDC with the added fillet plate and increased column thickness has a better performance than the originally proposed design<b>.</b></p>

Abstract An advanced jarring method was developed for deviated wells where conventional jarring is not possible. Comparing the results of jarring impact with this new method to jarring impact with conventional methods showed similar effectiveness. Rather than relying on gravity or energy stored in the cable (slickline or e-line), a high-performance, fully adjustable spring jar uses an accelerator to provide consistent energy storage and delivery during the jarring operation. However, this cannot be used in highly deviated wells because there may not be enough cable pull to energize the accelerator and perform an effective jarring event. To enable this, a wireline linear actuator can be used to pull and energize the accelerator and fire the jar effectively. In addition, having a jar and a linear actuator combined on the same run can allow for a more efficient fishing strategy by combining jarring and a straight pull or push. To prove the feasibility of this method, a system integration test was performed in which the linear actuator was used to fire the high-performance jar through an accelerator. In this test, the jarring force and the acceleration of the fish (the element being jarred) was measured and compared to standard jarring without the linear actuator. The measurements showed that it does not make a difference whether the jar is fired by the cable or by the linear actuator; the same force and acceleration (i.e., shock level) was imparted. This means that the linear actuator can be used to fire the jar without losing effectiveness. To achieve maximum efficiency, jarring and straight-pulling can be combined in the same run during which the two can be alternated to maximize results. This method is novel because it enables jarring in highly deviated wells and allows for jarring and straight-pulling on the same run, creating a more comprehensive fishing strategy.

The present study is aimed at investigating the effect of solder mask thickness on the solder ball shear test. Compared to the ball pull test, less brittle failures were found in the ball shear test. This is most likely caused by the support of solder mask. So far there is not publication reporting the effect of solder mask in detail. In this paper, specimens with various thicknesses of solder mask were fabricated and a series of ball shear tests were conducted. Cold ball pull (CBP) tests were performed as well for parallel studies. The attachment strength of solder balls under multiple reflows was evaluated as an index for comparison. The test results indicate that, in ball shear tests, brittle failures can be identified more easily in specimens with thinner solder mask after multiple reflows, especially for tests with higher shear speed and more reflows. No obvious effect of solder mask thickness on the ball pull test was found, regardless of different pulling speeds and multiple reflows.

Abstract The split-sleeve cold expansion process enhances the durability of metallic structures by imparting deep compressive residual stresses around fastener holes to extend the fatigue lives of the fastened structures. This study aims to improve the accuracy of the pulling force estimation by establishing the variable friction model of the dry-lubricated split sleeve when cold working an aluminum 2024-T3 hole. The variable friction model was empirically obtained from the friction experimental setup simplified from the split-sleeve cold expansion process. The contact-pressure-dependent variable friction model was derived through a systematic design of experiments approach with three different normal stress conditions, namely low normal stress (220 MPa), medium normal stress (440 MPa), and high normal stress (660 MPa) to cover the range of normal stresses occurred in the cold expansion process. A full quadratic response surface model was drawn for the friction coefficient’s nonlinear relationship between the mandrel and the lubricated sleeve depending on the normal stresses. The variable friction model was verified with 3-dimensional friction test finite-element (FE) simulations. This FE modeling validates the variable friction model to predict the pulling forces accurately to show a sound agreement between the estimated values and the experimentally obtained values. We conducted split-sleeve cold expansion experiments with 12.7 mm thick Al 2024-T351 alloy coupons to obtain the pulling force profile. The hole size was an average of 5.746 mm and the sleeve thickness of 0.152 mm to achieve approximately 4% radial expansion. Two 3-dimensional (3D) FE numerical analyses of the same split-sleeve cold expansion process were conducted using the variable friction model and a constant frictional coefficient of 0.05. The pulling force profiles from the FE modeling with the variable friction model closely align with those from the experiments to show the four distinct regions.

In atomic force microscopy (AFM) -based single molecule force spectroscopy, it is assumed that the pulling angle is negligible and that the force applied to the molecule is equivalent to the force measured by the instrument. Although this assumption may hold for flexible, compact molecules, studies have shown that it may not be appropriate for fairly rigid molecules, where measured forces can be a fraction of the actual values experienced by the molecule. Previously, we have proposed a method to align a molecule’s substrate and cantilever attachment sites and tested it in a simulated environment. Here we continue our work and test the alignment program in an experimental environment. In this paper we demonstrate that circling-induced force fluctuations are the result of stretching and relaxing a tethered molecule and we present the results of an alignment trial. Combined, these preliminary results demonstrate the feasibility of the alignment program and are a promising step towards correcting pulling geometry errors in single molecule force spectroscopy studies.

medicine, industry, and biotechnology. Fungi produce a wide range of bioactive compounds, such as alkaloids, antibiotics, antifungals, immunomodulators, anticancer agents, enzymes, and vitamins. However, these compounds are often locked inside the fungal cell wall, which is composed of chitin, a tough substance that is dif�icult to digest by humans1. Therefore, it is essential to have a good extraction technique that can break down the chitin and release the valuable compounds from the fungi, this is especially essential in the laboratory for accurate lab assays and potency determination during routine HPLC chromatography analysis. During licensure and/ or certi�ication any given lab will be required to take a pro�iciency test which gauges the lab’s pro�iciency at measuring a given matrices for accurate evaluation. They evaluate our abilities to run the gear and accurately measure the potency of what was extracted; however, at the time of this writing none existed for extraction of the fungal material itself, so this remains a variable between testing labs. It is important that we openly share our extraction techniques for evaluating fungi materials speci�ically for the clean extraction of active alkaloids for which potency can be measure via chromatography and/or spectrometry devices. In this way hopefully creating less variables between testing lab and more concise results. In this paper, we present a novel sample prep and extraction technique for fungi that uses speci�ic solvent composition in conjunction with M.A.E (microwave assisted extraction) in 75% methanol , 25% water which helps break the cell wall to release the compounds. Also used is an ultrasonication unit and vortex mixer. Our technique quickly releases all the available alkaloids for accurate chromatography measurements in just two hours, forty-�ive minutes with minimal handling. We demonstrate the effectiveness and ef�iciency of our technique by applying it to magic mushroom fruit bodies for the extraction of tryptamines namely psilocybin and its active derivative psilocin; however, this technique can be used for other species of fungi and compounds like Cordyceps/ cordycepin or Lions’ mane/ erinacines, etc.. We also compare our technique with other popular methods in terms of extraction techniques, digestion times and solvent compositions. Our results show that our technique is superior to the others in terms of time and effectiveness while pulling all the active compounds and not degrading them. Our extraction technique for fungi chromatography analysis offers a new and improved way to access the natural products of fungi and explore their potential for various biotechnological applications. We hope that our technique will inspire further research and innovation in the field of fungal extraction and natural product.