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La transición hacia el uso del papel para la enseñanza de la escritura en las escuelas elementales públicas en México no fue sencilla. Al finalizar el siglo XIX, se había cuestionado el uso de las pizarras por el riesgo que representaban para la salud, pues muchas veces los estudiantes borraban sus escritos con saliva y el material con el que estaban fabricadas no siempre guardaba las especificaciones necesarias, además el ruido al escribir era insoportable. En cambio, el papel, desde el punto de vista higiénico, pedagógico y estético, fue considerado un material superior frente a la dureza de la pizarra, el brillo de la superficie y la poca precisión que se obtenía en el trazo de las letras. Derivado de este planteamiento, se vislumbró seriamente la posibilidad de la adopción de papel en las escuelas oficiales. Sin embargo, este material era escaso y muy caro. Hacia el cambio de siglo, sólo dos fábricas de papel podían surtir a las escuelas y era necesario que abarataran el precio, que el sistema de distribución garantizara el abastecimiento y que el suministro fuera continuo. Este artículo analiza el inicio del proceso de reconversión de una tecnología para la enseñanza como era la pizarra por el papel. Analizo el gasto que significó y cómo esta modificación fue resultado de una multiplicidad de relaciones sociales, culturales, económicas y políticas que se entrecruzaron para dar una nueva configuración del tiempo, el ruido y los valores establecidos en el salón de clases. The transition to the use of paper in public elementary schools in Mexico was not easy. At the end of the nineteenth century, the use of slates had been questioned due to the health risk they represented since students often erased their writing with saliva and the material with which the slates were made did not always meet the necessary specifications. On the other hand, paper, from a hygienic, pedagogical and aesthetic point of view, was considered a superior material compared to the hardness of the slate, the shine of the surface and the lack of precision obtained in the tracing of the letters. Derived from this approach, the possibility of changing materials in official schools was seriously envisioned. However, the paper represented a very high cost. Only two paper mills could supply the schools and it was necessary to lower the price, and guarantee the supply by enhancing the distribution system. This article analyses the beginning of the conversion process of a technology for learning to write such as the slate for paper. I analyse the expense that it meant for the authorities and families, how the change was the result of a multiplicity of social, cultural, economic and political relations that intersected to give a new configuration of time, noise and established values in the classroom. [ABSTRACT FROM AUTHOR]

Inspired by a type of quarrying waste nicknamed "bastard rock", this paper uses the concept "bastard" as an analogy for industrial heritage landscapes: conceptually and physically difficult, inherently hybrid and comprised of contested lineages and inheritances. Advocating for relational landscape approaches in heritage management, this paper also addresses the exclusion of active industry from UNESCO World Heritage cultural landscapes and buffer zones, using the case study of Penrhyn Quarry in The Slate Landscape of Northwest Wales as an example of when "one-size-fits-all" heritage management strategies risk diminishing the cultural heritage they seek to preserve for future generations. [ABSTRACT FROM AUTHOR]

Rock is a commonly used building material. Studying rock properties can reduce production time and cost, improve production efficiency and construction safety. Therefore, rock mechanics characteristics, especially strength, have always been a hot field of rock mechanics. Classical strength criteria such as the Mohr-Coulomb (M-C) criterion and Hoek-Brown (H-B) criterion are based on rock strength homogeneity and cannot reflect the characteristics of layered rock strength changing with azimuth. Therefore, it is necessary to modify the classic strength criterion to reflect layered rock anisotropy. Based on existing triaxial test results and rock anisotropic strength properties, an improved H-B criterion for rock anisotropy considering the effect of critical confining pressure is proposed in this paper, which can be used to calculate the strength of layered rocks. Taking slate as an example, the calculation results of the improved H-B criterion show that: 1. the improved H-B criterion can mostly control the mean absolute percentage error (MAPE) of McLamore slate test results within 30%, which is obviously better than the classical H-B criterion and has good extrapolation ability; 2. the material parameters m, n are determined by test results and inversion analysis, which avoids the arbitrariness. The proposed method can be used as a supplementary and alternative method to estimate or calculate the strength of layered rock. [ABSTRACT FROM AUTHOR]

This paper presents the results of a laboratory simulation of a subarctic climate carried out in climatic chamber. Realistic daily and seasonal cycles of temperature of a regular subarctic continental climate without dry seasons (Dfc) were simulated and the physical/mechanical properties and performance of the slates were assessed. The slate was selected because of its use as cladding and roofing material in cold regions. Mechanical performances before and after Dfc climate simulation were evaluated through point load index, uniaxial compression, flexural strength and anchor rupture load. A decrease in these mechanical features between 9 and 50% with respect to the initial strengths has been registered. Other physical parameters such as apparent density, open porosity and water absorption were evaluated. The tests showed an increase in open porosity (+72%) and a decrease in bulk density (−0.7%). The results highlighted a predominantly physical decay and mechanical performance decreasing with a relevant lowering in strength without the detection of chemical–mineralogical alterations. Moreover, artificial sun exposure reproduced the weak solar radiation that characterizes the Dfc climate. This was carried out to assess the aesthetic characteristics of the slate, since discoloration under sun exposure was supposed to occur but the slates did not exhibit substantial color changes. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Railway Science & Engineering is the property of Journal of Railway Science & Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

During the height of the Industrial Revolution, North Wales was the largest global producer of slate. Welsh slate was extensively utilized as a roofing material by industrializing countries around the world in the late nineteenth century. Although several surface quarries remain open, the last underground slate mines in Wales closed in the 1960s. An industry that once employed more than 17,000 now supports 400 jobs in the region. Today, slate tourism sites tell the story of this important aspect of North Wales' industrial and geologic heritage. In 2012, a "Slate Industry of Wales" site was nominated to the UNESCO World Heritage Tentative List by the UK. Though Welsh coal tourism sites have been widely analyzed in the literature, few studies have investigated the country's slate tourism. This paper explores the interpretive discourses presented at three prominent slate tourism attractions in North Wales and compares them with the justifications provided for World Heritage designation. Among the themes discussed are the importance of Welsh slate, geo-interpretation, slate technology, the life of Welsh quarrymen, and impacts of slate mining. [ABSTRACT FROM AUTHOR]

Abstract The subgrade crushed-rocks of Gonghe-Yushu (Gongyu) Expressway in Qinghai Province are seriously weathered, resulting in a series of pavement diseases. Among the weathered crushed-rocks, the weathering degree of slate is particularly serious, and its physical and mechanical properties, weathering resistance and applicability are not clear. Therefore, this paper takes the slate in the subgrade crushed-rocks of Gongyu Expressway as the research object, and drills the core of the slate rock block to make a cylindrical standard sample, and uniaxial and triaxial compression tests, nuclear magnetic resonance tests, and electron probe micro-analysis tests were performed on it within 50 freeze–thaw cycles (FTC) under saturated conditions. According to the test results, the mass, longitudinal wave velocity, and strength of the slate specimens all decrease with the increase of the number of FTC, the cohesion $$({\text{C}})$$ ( C ) increases first and then decreases, and the change trend of internal friction angle (φ) is completely opposite to the cohesion. The FTC has an expansion effect on the pores of the slate specimens, and the microstructure of the rock particles on the specimen’s surface is removed and becomes smooth. The results of mechanical tests are used in the Hoek–Brown (H-B) strength criterion, and a unified expression of the H-B criterion suitable for slate in permafrost regions is established. The above conclusions can provide some construction reference and maintenance of high-grade highways in cold regions.

A new method is proposed in order to estimate the shear strength of schistosity planes in slate in terms of Mohr–Coulomb cohesion and internal friction angle. The procedure consists in carrying out the Brazilian method under different loading-foliation angles, for which experimental tests were achieved in slates from the northwest of the Iberian Peninsula (Spain). The experimental fracture patterns were analytically studied and justified by simulating the stress field in the discontinuity planes contained in the whole sample, taking into account the first failure registered in the tests. By combining experimental and analytical studies and a procedure based on the representation of the threshold state of stresses—in the elastic regime—in the failure plane, it is possible to estimate the foliation's strength envelope through a lineal adjustment according to the Mohr–Coulomb criterion and, thus, to characterize the layering. Finally, the proposed procedure was validated by the direct shear test. The cohesion and the internal friction angle obtained with this convenctional test were very close to that calculated by the proposed method, verifying the methodology developed by the authors. This procedure may be interesting in various engineering applications, either in the study of the properties of cleavage in slate, which is commonly used as an industrial rock, or in dam foundations, underground excavations and slope engineering, since one of the main failures in civil engineering is due to sliding along weak planes. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Heilongjiang University of Science & Technology is the property of Journal of Heilongjiang University of Science & Technology Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Using over 20,000 electoral slates from municipal elections in the Czech Republic, we document that in proportional representation electoral systems political parties rank candidates on the slates systematically according to their valence, measured by educational attainment, and intra-party value, measured by political donations and membership. The observed patterns are consistent with market mechanisms where the party leaders benefit from the valence and intra-party value of candidates and offer slate positions (i.e. the probability of winning a mandate) in exchange. We show that candidates with high valence and those who possess more intra-party value are placed in better-ranked positions, despite the fact that candidates with more intra-party value, conditional on observables, tend to receive relatively fewer votes than candidates with low intra-party value. We further show that as a party expects to hold more council seats, the share of their candidates with higher intra-party value increases. [ABSTRACT FROM AUTHOR]

The Scottish slate industry is much less well-known, even in Scotland, than the corresponding industry of North Wales. No doubt this is mainly due to its much smaller size, and perhaps also to the geographical remoteness of its location. Apart from some minor quarries which shall be mentioned later, it was concentrated in two main places: Ballachulish, about 10 miles of Fort William, Scotland and the so-called Slate Islands, of which the most important was Easdale, about 11 miles of Oban, Scotland. The industry had certainly started in both places before the end of the seventeenth century; in Easdale before 1631 and at Ballachulish in 1697. This paper is concerned principally with the industry in the Slate Islands. Although at first (and probably for the first two centuries or so) it was the dominant component of the Scottish slate industry, the main reason for the limitation of the coverage of this paper is that, while there is quite good documentation of the industry in the Slate Islands, practically none has so far been found for that at Ballachulish. The Slate Islands were part of the estate of the Breadalbane family, and many of the records of the Marble and Slate Co. of Netherlorn, Scotland formed in 1745 with the Earl of Breadalbane as one of the partners, have been preserved in the Scottish Record Office.

Slate typically possesses a pronounced layered structure and tends to soften when exposed to water, leading to numerous detrimental effects on the construction of related underground projects. In this study, X-ray diffraction (XRD) analysis was first performed to investigate the mineral composition of the typical slate from Changsha, China. Then, uniaxial and triaxial compression tests under varying bedding angles (i.e., 0°, 30°, 45°, 60°, and 90°) and moisture levels (i.e., dry state, natural state, and saturated state) were conducted to explore the anisotropy characteristics and susceptibility to water-induced softening of the slate. The results reveal that: (1) The exposure of slate to water exacerbates the deterioration of its layered structure, making it more prone to shear failure along the bedding planes. Furthermore, the energy released during shear-slip damage is reduced, which is macroscopically manifested by the decrease in slate brittleness and the increase in plasticity. (2) The slate's compressive strength, elastic modulus, and cohesion vary in a U-shaped pattern with the increase in bedding angles. However, Poisson's ratio and internal friction angle are slightly affected by the bedding angle and water content, which do not exhibit a clear variation pattern. (3) In addition, the formulations for strength and stiffness predictions of slate were also discussed in this study. The results show that the modified Hoek–Brown criterion characterizes the uniaxial and triaxial compressive strengths of slate more accurately, and the generalized Hooke's Law more effectively predicts the elastic modulus. [ABSTRACT FROM AUTHOR]

Planes of weakness like schistosity and foliation affect the strength and deformational behaviors of rocks. In this paper, an attempt has been made to study the elastic and strength behavior of slate rocks obtained from foundation of Sardasht dam site in Iran. Wet and dry specimens with different orientation of foliation were evaluated under uniaxial, triaxial, and Brazilian tests. According to the results obtained, slate mechanically pronounced U-shaped anisotropy in uniaxial and triaxial compression tests. In addition, the degree of anisotropy for the slates tested in current study was relatively high, showing the effect of foliation plane on strength and elastic parameters. It was concluded that stiffness of the samples decrease as the angle of anisotropy reaches 30-40°. This change was more pronounced for wet comparing to dry samples. However, the tensile strength obtained during Brazilian tests indicated that there is no apparent relationship between angle of anisotropy and tensile strength. However, increasing the water saturation decreased the tensile strength of the samples. The calculated elastic moduli referring to different anisotropy angles could be valuable for the design of various engineering structures in planar textured rock masses. [ABSTRACT FROM AUTHOR]

Highlights • FLAC with ubiquitous-joint (UBI) model and the Burger-creep viscoplastic (CVISC) model. • The new hybrid UBI/BUR model was implemented as a UDM program for FLAC analyses. • The hybrid model can be used for simulation of tunnelling in anisotropic time-dependent formations. Abstract Slate is a metamorphic rock often contains a dense foliated texture called slaty cleavages or schistosities. The ease of split along the schistosities weakens the slate and its resistance to weathering and erosion. For the tunnel excavation in slate formations, it is common to observe anisotropic deformation; in addition, the deformation caused by stress release also shows time-dependent behavior. Hence, anisotropic and time-dependent behaviors must be taken into account to more properly estimate the deformation of tunnel excavation in slate formation. In this paper, the computer software FLAC with the ubiquitous-joint (UBI) model and the Burger-creep viscoplastic (CVISC) model was adopted for the analysis. To more efficiently obtain relevant parameters of those models, back calculations were performed by the automatic iterative tool Quick Macro. Coupling these two models, the new hybrid UBI/BUR model was developed and implemented as a UDM program, which can be applied for the FLAC analyses. The new model was calibrated by the monitoring data from a slate tunnel excavation project, i.e., the Wanta-Sunglin Project in Taiwan, then applied for detailed analyses. The results indicate that the hybrid model developed in this study is better than the conventional models, and can be used for the simulation of tunnel excavation in anisotropic time-dependent slate formations. [ABSTRACT FROM AUTHOR]

This paper proposes a method to enzymatically treat poor-quality cocoa almonds (known as 'slate') to ensure the formation of chocolate flavor precursors. The production of flavor precursors improves the quality of these almonds, which are usually responsible for the low quality of the liquor produced. Proteases and carboxypeptidases from different sources were tested under various conditions. The different treatments were evaluated by chemical analysis (hydrolysis efficiency) and sensory analysis of the treated material compared to good-quality cocoa almonds. The results show that it is possible, through the use of microbial enzymes, to generate the mixture of compounds that will release, after roasting, the characteristic chocolate flavor in poor-quality almonds. However, it is necessary to optimize the conditions of enzymatic treatment to obtain better results and thus establish a process that can be used for industrial purposes for manufacturing cocoa and chocolate. The basidiomycete Moniliophtora perniciosa is the causative agent of witches' broom disease (WBD) of the cocoa tree, whose seeds are the source of chocolate. It is the most important phytopathological problem of cocoa-producing areas of the American continent, and has decimated the Brazilian cocoa industry. In Bahia (Brazil), M. perniciosa was identified in 1989 and, as a consequence of its spreading, the annual production of cocoa almonds dropped from 450000 to 90000 tons within 12 y, reducing export values from an all-time high of about US$ 1 billion to 110 million. The high incidence of WBD incapacitates Brazil to produce enough cocoa almonds even for the internal market, leading the country to import low-quality cocoa almonds mainly from African countries. Our work proposes an enzymatic treatment to increase the quality of that cocoa almonds and, consequently, to improve the quality of the chocolate produced and consumed in the country. [ABSTRACT FROM AUTHOR]

The experimental and numerical investigations presented in this paper were carried out to determine the splitting forces and crack propagation scenarios of naturally bedded layered slate rock. Splitting loads were determined by impact splitting of regular-sized slate blocks under plane strain test loading conditions, using a hydraulic actuator with a wedge-shaped indenter. The mechanical properties of slate blocks required for numerical analyses were obtained from detailed experimental testing. The velocity of dynamic crack propagation in slate blocks under indenting wedge impact loading was determined using a series of strain gauge sensors. Numerical studies were carried out using ABAQUS, a general purpose, finite element analysis (FEA) program. Mode I dynamic crack propagation was simulated numerically by the gradual releasing of the restrained node on the symmetric plane of the specimens. Mode I stress intensity factors were computed for different crack lengths and the results were compared with the plane strain material fracture toughness obtained from earlier experiments/FEA. Very good agreement was obtained between analysis results and the measured fracture toughness value of slate, for the applied impact splitting load. Using the equation derived from a parametric study, of results obtained from the numerical analysis of different sizes of slate blocks, the maximum theoretical impact splitting force was determined using the plane strain fracture toughness value obtained from FEA. The difference between the loads obtained from the experimental studies and the derived empirical equation, varied between + 4.96% and −32.34%. [ABSTRACT FROM AUTHOR]

Critical for an efficient and effective exploitation of a slate mine is to obtain information on its technical quality, in other words, on the exploitability potential of the deposit. We applied support vector machines (SVM) and LS-Boosting to the assessment of the technical quality of a new unexploited area of a mine, and compared the results to those obtained for kriging and neural networks. Firstly we analyzed the relationship between kriging and semi-parametric SVM in a regularization framework and explored the different alternatives for training these networks. Subsequently, in an attempt to combine both radial and projection structures, we formulated a boosting technique for radial basis function (RBF) networks defined over projections in the input space (RBFPP). The application of these techniques to our test drilling data demonstrated a similar level of performance for all the estimators examined, with the main difference occurring in the shape of the respective deposit reconstructions. Therefore, in choosing between the different techniques, an essential aspect will be their ability to reproduce the morphological characteristics of the true process. In this paper we also evaluate the benefits of using the estimated covariogram as the kernel of the SVMs and compare the sparsity of the different solutions. The results obtained show that the selection of a standard kernel that ignores the variability structure of the problem produces poorer results than when the estimated covariogram is used as the kernel. [ABSTRACT FROM AUTHOR]

In numerical modelling, selection of the constitutive model is a critical factor in predicting the actual response of a geomaterial. The use of oversimplified or inadequate models may not be sufficient to reproduce the actual geomaterial behaviour. That selection is especially relevant in the case of anisotropic rocks, and particularly for shales and slates, whose behaviour may be affected, e.g. well stability in geothermal or oil and gas production operations. In this paper, an alternative anisotropic constitutive model has been implemented in the finite element method software CODE_BRIGHT, which is able to account for the anisotropy of shales and slates in terms of both deformability and strength. For this purpose, a transversely isotropic version of the generalised Hooke's law is adopted to represent the stiffness anisotropy, while a nonuniform scaling of the stress tensor is introduced in the plastic model to represent the strength anisotropy. Furthermore, a detailed approach has been proposed to determine the model parameters based on the stress–strain results of laboratory tests. Moreover, numerical analyses are performed to model uniaxial and triaxial tests on Vaca Muerta shale, Bossier shale and slate from the northwest of Spain (NW Spain slate). The experimental data have been recovered from the literature in the case of the shale and, in the case of the slate, performed by the authors in terms of stress-strain curves and strengths. A good agreement can be generally observed between numerical and experimental results, hence showing the potential applicability of the approach to actual case studies. Therefore, the presented constitutive model may be a promising approach for analysing the anisotropic behaviour of rocks and its impact on well stability or other relevant geomechanical problems in anisotropic rocks.

This study presents a new landslide monitoring system, which is designed to be cost-effective, robust, flexible, and scalable, aiming for long-term and real-time monitoring and large-scale deployment in harsh and remote environments. This wireless monitoring system consists of the hybrid sensor node (including the GNSS receiver and MEMS accelerometer), the GNSS antenna, the power supply system, and the data center with a big-data infrastructure. The system was deployed at Songmao and Lushan landslide-prone sites, Taiwan, and its effectiveness was also examined through monitoring real landslide events. It was found that continuous monitoring, combining displacement and vibration data, enables us to see how and when the landslide is triggered by the rainfall, together with the potential sliding direction, and the associated aftermath behavior, even after the rainfall stops. The entire landslide movement, from initiation to the subsequent continuous movement, can be captured in detail through the DGNSS analyses. The potential landslide direction is derived based on the directivity from the Horizontal to Vertical Spectral Ratio (HVSR) analyses on the seismic measurements by the 3-axis accelerometers. The monitoring results also agree with other measurements from the borehole inclinometer/extensometer and total station. At these two sites, the groundwater level exhibited a distinct time lag in rising after the rainfall started and the subsequent sudden increase triggered the landslides. On the contrary, the drawdown of the groundwater level was relatively slow, which is due to the anisotropic permeability of the slate, and therefore promotes the continued slope movement even after the rainfall ceased. Water-softening on the slate along the sliding surface, which was just fractured by landslide movement, could be one of the associated underlying mechanisms. [ABSTRACT FROM AUTHOR]

Measuring the abundance and size distribution of framboidal and euhedral microscopic crystals of pyrite has proven to be an effective method to determine the paleoenvironmental conditions in sedimentary rocks bearing these minerals. However, micropyrites can be found in other geological environments as well, such as low-grade metamorphic and hydrothermal. In these cases, their sizes and distributions are expected to be different from those deposited in a sedimentary environment, due to the different genetic processes involved. This paper analyzes the size and distribution of the micropyrite population in a low-degree metamorphic slate, originally formed under anoxic to low-oxygen conditions. The geological record of this rock suggests that micropyrite formation took place in different stages, resulting in different population distributions. Traditionally, SEM has been used to characterize micropyrite populations. However, for this study, a new technique in this field was applied, namely, high-resolution X-ray tomography (micro-CT), which allows for 3D visualization and analysis of the stone's structure, based on the differences in the X-ray attenuation coefficient of the component minerals. As complementary technique, transmitted and reflected optical microscopy was used. Size and population distributions of the micropyrites were measured using SEM and micro-CT and then statistically analyzed. SEM was able to determine the morphology and size of micropyrites in 2D, while micro-CT provided statistically relevant information about the size histogram of the micropyrites. The data obtained indicate the existence of three overlapping populations of micropyrites. Two of them have small sizes and a narrow range of distribution, which can be attributed to sedimentary processes, and the other have larger sizes and a broader range of distribution, attributed to the effect of metamorphic processes. In summary, micro-CT coupled with SEM and accurate statistical analysis proved capable of differentiating between overlapping micropyrite populations in a sample of low-grade metamorphic slate. [ABSTRACT FROM AUTHOR]

Sichuan–Tibet railway tunnels are generally long and deep, and some of them pass through layered slate, which is prone to failure under high in situ stress. Insight into the mechanical behaviors of deep slate under different stress environments is critical to the safety of engineering practices in this area. To this end, we studied the energy characteristics and micro-cracking behaviors of slate samples under different triaxial loadings. The results showed that the confining pressure increased the strength, elastic modulus, Poisson's ratio and crack characteristic stresses of the studied slate. As the confining pressure increased, the storage of elastic strain energy during the prepeak stress stage increased, and its release during the postpeak stress stage was inhibited. Additionally, we obtained the slate failure precursors by analyzing the acoustic emission (AE) evolution characteristics, i.e., "a sudden increase in AE metrics, followed by a quiet period, and then a sudden increase again" in terms of the AE count rate and AE energy rate after obvious expansion of the sample. Then, we further observed that with an increase in confining pressure, a gradual transition of the failure pattern from compressive shear to tensile shear occurred. Finally, we discussed the influence mechanisms of confining pressure on the slate failure behaviors and concluded that the change in the effective shear stress along the foliation planes played an important role in the failure mode transition. [ABSTRACT FROM AUTHOR]

The Sotuta pottery complex has been used in the archaeology of the northern Maya lowlands to identify the Terminal Classic period and cultural association with Chichen Itza. The Sotuta complex, however, is made up of many pottery types, the majority of which are inappropriate markers of elite sociopolitical history. It is argued here that Sotuta-complex slate wares developed out of previous local slate wares regardless of the elite sociopolitical changes taking place with the arrival of the Itza. The wares produced and distributed by commoners were independent of elites and have been artificially chained to questions of elite political expansion for which they are inappropriate correlates. [ABSTRACT FROM PUBLISHER]

From its appearance in Seattle in 1999 up to the recent Arabic Springs, the Black Bloc has been present in the major manifestations for the Global Justice Movement, where it often played an important role in directing the protests. Nevertheless, in spite of the media echo, social dentist barely deserved their attention to the phenomenon. Likewise, the use of the violence has benn seen as incompatible with a democratic policy. In this paper I want to analyze the phenomenon of the political violence in the Black Bloc. In the first part I will try to identify the type of violence from the categories of political violence as they have been formulated by the social movements theorists. Later I will offer a different interpretación of Bloc's identity and action which will let to contextualize the phenomenon inside the web and democratic form of protest which have developed in the last decade. [ABSTRACT FROM AUTHOR]

On 27 March 2021, a landslide with a volume of approximately 2 × 104 m3 occurred in Guocun Village next to Kengheng road in Tonglu County, Zhejiang Province, China. The landslide caused no casualties as a result of timely road closures, because of the unusual noises detected early by local residents. The motion mechanism of the landslide was studied using video analysis. Slope cutting resulting from road construction might have been the major triggering factor for the landslide. The intrusion of magma and the uplift process of Huangshan led to the metamorphism of mudstone to easily fractured slate, and the brittle layered slate might have controlled the change of motion from transitional sliding to dry debris flow. [ABSTRACT FROM AUTHOR]

In the present study physicochemical characterization of slate sample was carried out which was collected from slate mine in Lasbela District, Baluchistan. Slate was evaluated for its effectiveness as partial replacement of ordinary Portland cement (OPC) in the production of Portland Pozzolana cement (PPC). The grain size analysis of crushed slate sample using ball mill revealed that maximum fraction retained on 44 μm was about 72.8 %. Sum of the major oxides (SiO2 + Al2O3 + Fe2O3) is about 90.09 % that meet the requirement as per ASTM C 618 (minimum 70.0 %). Other oxides including SO3 (<0.05), CaO (4.04), MgO (1.66), K2O (0.10), Na2O (0.16), TiO2 (0.35), MnO (<0.02) and Cl (0.12) also meet the international standard of ASTM C 618 for PPC. OPC without and with using slate sample in a ratio of 5 % and 10 % with clinker was tested to measure compressive strength, physical tests and setting time. The results showed that after 5 % and 10 % replacement, insignificant effect was observed on the physical properties, setting time and compressive strength in 2-, 7- and 28-days curing. Hence, slate can be used as natural pozzolan for manufacturing PPC. It is cost effective for the production of cement as well as to sustain the resources of limestone for long time and reducing emission of CO2 in the environment. It can also be used in the sulfate rich environment, coastal areas especially for the construction of dams and bridges. [ABSTRACT FROM AUTHOR]

This paper presents the results of a laboratory simulation of a subarctic climate carried out in climatic chamber. Realistic daily and seasonal cycles of temperature of a regular subarctic continental climate without dry seasons (Dfc) were simulated and the physical/mechanical properties and performance of the slates were assessed. The slate was selected because of its use as cladding and roofing material in cold regions. Mechanical performances before and after Dfc climate simulation were evaluated through point load index, uniaxial compression, flexural strength and anchor rupture load. A decrease in these mechanical features between 9 and 50% with respect to the initial strengths has been registered. Other physical parameters such as apparent density, open porosity and water absorption were evaluated. The tests showed an increase in open porosity (+72%) and a decrease in bulk density (−0.7%). The results highlighted a predominantly physical decay and mechanical performance decreasing with a relevant lowering in strength without the detection of chemical–mineralogical alterations. Moreover, artificial sun exposure reproduced the weak solar radiation that characterizes the Dfc climate. This was carried out to assess the aesthetic characteristics of the slate, since discoloration under sun exposure was supposed to occur but the slates did not exhibit substantial color changes.

Copyright of Archiv für Diplomatik, Schriftgeschichte, Siegel- und Wappenkunde is the property of Vandenhoeck & Ruprecht GmbH & Co. KG and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Sand has been the main filter media used in rapid gravity filtration since its introduction. The dominance of sand has been due to its low cost and availability. Extensive experience has led to sand filters with a dependable and predictable performance. Sand remains the preferred filter medium but usually with a larger sized anthracite capping to reduce the onset of head loss. Other approved filter media are now commercially available and this paper compares sand with recycled glass, Filtralite® and slate at pilot scale. The results have reaffirmed the basic importance of p.article size on head loss and turbidity performance rather than surface activity or specific surface area. The results did suggest, however, that particle shape and packing exerted a stronger influence on performance than previously acknowledged. These could be used to improve the design and the contribution to sustainability made by rapid gravity filters. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a model for aircraft slat noise prediction, based on the theory of aerodynamic sound generation and the first principles of source flow physics. Starting from the theory of acoustic analogy, the noise from the high Reynolds number and low Mach number flows in the slat cove region is formulated as a general solution by the method of dimensional analysis, far-field asymptotic expansion and statistical modeling. The solution relates the far-field noise spectrum to the surface pressure statistics, the characteristic length and time scales in the surface pressure statistics and Green''s function that accounts for the sound-flow coupling and propagation effects. The general solution is then used to extract scaling laws and correlation models for the individual functional dependences between the far-field noise and various parameters, including the slat noise spectral shape, its Mach number dependence and its far-field directivity. The simple scaling laws and correlation models are validated by test data and serve as building blocks to construct a slat noise prediction model. [Copyright &y& Elsevier]

Abstract: This paper describes the mobilization and speciation of As found in hydrothermally altered rock under oxic column conditions. The altered rock sample was obtained from a tunnel project located in the Nakakoshi area of Hokkaido, Japan, whose geology is represented by slate, shale and sandstone. This area has undergone silicification, pyritization and argillic alteration resulting in As-enrichment of the rock. Results of the column experiments show that the infiltration rate, bulk density and rock bed thickness affected the duration of water residence, which in turn influenced the pH of the rock–water system. Coexisting ions most notably Ca2+ at amounts greater than ca. 50mg/L retarded the mobilization of As. Mobilization of As from the rock with time occurred in two stages: stage 1 (weeks 1–20) with higher As leaching and stage 2 (weeks 20–76) characterized by nearly constant As release. In addition, pore water As concentrations revealed that the columns developed into two regions: the top half where most of the leaching occurred and the bottom part dominated by adsorption. Thus, the mechanism controlling the mobilization of As from the rock is a combination of one or more of the following processes: dissolution of soluble As-bearing fractions, pyrite oxidation and adsorption reactions. Arsenite (As[III]) was the dominant species in the effluent at the start of the experiment in columns with shorter water residence time and lower pH conditions (<8). On the other hand, arsenate (As[V]) was the major inorganic species released from the rock at higher pH (8–9.5) and when the system was close to equilibrium. Speciation of As with depth also indicated that As[III] disappeared around the bottom half of the columns, probably as a result of adsorption and/or oxidation. Arsenic speciation is partially controlled by the pH dependent adsorption of As species. The important adsorbent phases in the rock included Fe–Al oxides/oxyhydroxides, clay minerals and organic matter, which permitted the columns to attenuate additional As loadings including As[III]. Implications of these results on the design of a novel disposal method for these altered rocks include the enhancement of As adsorption through the addition of natural or artificial adsorbents and the utilization of a covering soil with low permeability to minimize rainwater infiltration into the rock. [Copyright &y& Elsevier]

Abstract: Recently, substantial interest has developed in using fine lightweight aggregate for internal curing in concrete. Mixture proportion development for these mixtures requires the specific gravity, water absorption, and water desorption characteristics of the aggregate. This paper presents results from a recent study in which the properties of commercially available expanded shale, clay and slate lightweight aggregates (LWA’s) were measured. This research measured the time-dependent water absorption response for the lightweight aggregate. The results indicate that a wide range of 24h water absorption values exist for commonly used fine lightweight aggregates (e.g., absorption between 6% and 31%). Desorption was measured and it was found that between 85% and 98% of the 24h absorbed water is released at humidities greater than 93%. These properties can be normalized so that they can be efficiently used in proportioning concrete for internal curing. Normalized plots of absorption and desorption demonstrate benefits for a single function that describes a large class of expanded shale, clay, and slate aggregate for use in internal curing. [Copyright &y& Elsevier]

Abstract: Substitution of slate roofing tiles is a conventional operation during building restoration, since tiles are very difficult to restore or clean because of the high degree of alteration they suffer. Criteria for replacement of historical building stones must be based on geological, geotechnical and esthetic parameters, among which color is of great importance. In this sense, this paper constitutes a comprehensive and useful colorimetric study of roofing slates from the Iberian Peninsula, for the purposes of restoration. The color of 50 commercial varieties of roofing slate mined in quarries from the 12 mining districts in the Iberian Peninsula was analyzed with a spectrophotometer device, by considering the CIELAB color space. The results of the study were used to develop a protocol for characterizing the color of roofing slate and to define the color range of roofing slate from the Iberian Peninsula. In addition, the similarities and differences in the color and microstructure of the different commercial varieties of Iberian roofing slate were established and the limit of acceptability of replacement of one type of slate by another was determined. Parameter hab was found to be the most important CIELAB color coordinate as regards the formation of homogeneous color groups, and the specular component excluded (SCE) mode was most sensitive as regards detecting color differences between two samples. [Copyright &y& Elsevier]

Abstract: This paper describes an experimental investigation on the flexural and anchorage strength of slate for cladding. The study has been conducted on sawed slate specimens, all showing the same surface finishing. Slate flexural strength was compared for two distinct situations: (i) using a 3-Point flexure loading configuration in batches of materials with larger cross-sectional specimen dimension (50×30mm2); and (ii) using a 4-Point flexure loading configuration in the same batch of materials but with smaller cross-sectional dimensions (30×25mm2). The 4-Point bending specimens were tested in three different directions considering slate anisotropy planes. Load was applied along the direction perpendicular to the planes of schistosity; and also along two directions parallel to the planes of schistosity. Slate anchorage strength has been determined on slate slabs with 400×200×30mm3 with dowel anchorage in 8mm diameter cylindrical holes with 35mm depth. Test load was applied perpendicularly to the schistosity planes. Cladding stone in building facades and its supporting systems must be compatible with the behaviour and performance of other interfacing systems, such as curtain walls and superstructure frames. In this sense, a properly executed dimensional stone cladding should be designed and installed within the capabilities and limitations of the slate’s support system to resist all active forces or actions. The results of this work reveal the importance of complementary characterization techniques for dimension stone cladding, particularly for anisotropic rocks as slates. From the results it is possible to conclude that schistosity planes have an utter influence on either anchorage or flexural strength. [Copyright &y& Elsevier]

The S tunnel is a 4.2 km-long headrace tunnel. In the tunnelling project, the ground was assumed to be hard slate and suitable for TBM excavation based on the primary site investigation. However, TBM jamming frequently occurred with the increase of the tunnel cover, and the TBM excavation was cancelled. In order to investigate the TBM jamming, theoretical analyses and seismic investigations were conducted. It was found that analytical model proposed in this paper well explained the influence of the cover on the possibility of TBM jamming. It was also found that the depth of the loosened zone was expanded 6–8 m at the location where TBM jamming occurred. [ABSTRACT FROM AUTHOR]

Non-occupational exposure to crystalline silica (quartz) in vicinity of slate pencil industry is reported. Ambient silica monitoring was carried out at two locations in the vicinity of slate pencil industry and one control site 5 kilometers away from slate pencil industry using PM-10 high volume samplers. Quartz content was analyzed using Fourier Transform Infrared Spectrophotometer (FTIR) from vertically elutriated dust samples collected simultaneously at all locations. It was found that average quartz concentrations in the vicinity of slate pencil industry and control site were 41.07–57.22 and 3.51 μg/m3, respectively. Results were compared with derived ambient air quality standard for silica based on findings reported by Environmental Protection Agency (EPA). [ABSTRACT FROM AUTHOR]

Upper Neoproterozoic successions in the North China and nearby Chaidam blocks are poorly documented. North China successions typically consist of a diamictite unit overlain by siltstone, sandstone, or slate. Similar successions occur in Chaidam, although a cap carbonate lies atop the diamictite Unit. The diamictites in both blocks have been variously interpreted as Cryogenian, Ediacaran, or Cambrian glacial deposits. In this paper, we describe problematic macrofossils collected from slate of the upper Zhengmuguan Formation in North China and sandstone of the Zhoujieshan Formation in Chaidam; both fossiliferous formations conformably overlie the aforementioned diamictites. Some of these fossils were previously interpreted as animal traces. Our study recognizes four genera and five species—Helanoichnus helanensis Yang in Yang and Zheng, 1985, Palaeopascichnus minimus n. sp., Palaeopascichnus Ineniscafus n. sp., Horodyskia moniliformis? Yochelson and Fedonkin, 2000, and Shaanxilithes cf. ningqiangensis Xing et al., 1984. None of these taxa can be interpreted as animal traces. Instead, they are problematic body fossils of unresolved phylogenetic affinities. The fundamental bodyplan similarity between Horodyskia and Palaeopascichnus, both with serially repeated elements, indicates a possible phylogenetic relationship. Thus, at least some Ediacaran organisms may have a deep root because Horodyskia also occurs in Mesoproterozoic successions. Among the four genera reported here, Palaeopascichnus Palij, 1976 and Shaanxilithes Xing et al., 1984 have been known elsewhere in upper Ediacaran successions, including the Dengying Formation (551–542 Ma) in South China. If these two genera have biostratigraphic significance, the fossiliferous units in North China and Chaidam may be upper Ediacaran as well. Thus, the underlying diamictites in North China and Chaidam cannot be of Cambrian age, although their correlation with Ediacaran and Cryogenian glaciations remains unclear. As no other Neoproterozoic diamictite intervals are known in North China and Chaidam, perhaps only one Neoproterozoic glaciation is recorded in that area. [ABSTRACT FROM AUTHOR]

Abstract: The paper commences with a description of the mining resource studied (roofing slate), the particular features of slate deposits and slate mining techniques. We then describe the methodology used for drilling core studies, the most reliable method for ornamental rock mining exploration. From the drill-core data, applying statistical techniques (kriging) with the assistance of the powerful DATAMINE 5 software package ([MICL, 1999. “Datamine 5”. Datamine Group. Mineral Industries Computing Limited.]) can make an assessment of the exploitable resources in a quarry. To do this, the research domain is first delimited – in terms of the top and bottom of the exploitable seam, as well as the sidewall boundaries – employing ordinary kriging. A wireframe model of the deposit (the domain) is constructed and is sub-divided into blocks (block model). The resources in the deposit are then evaluated using indicator kriging and taking into account the anisotropic directions of the slate deposit. This produces data in the form of locations, tonnages and percentages of exploitable slate. The final step compares results obtained from the model with results obtained from mining in order to arrive at conclusions respecting the methodology. [Copyright &y& Elsevier]

This paper describes the application, for the first time, of design, planning and scheduling algorithms to the mining of ornamental rock. For the application, a model of an ornamental slate deposit was created that included a block model and a financial model of the deposit. The block model contains information on useful or exploitable slate content, which is equivalent to metal content for the traditional mining sectors. The financial model introduces the concept of cutoff grades to slate. Cutoff grades are a logical consequence of the mine planner having a choice as to whether or not to use diamond wire to cut the blocks. The techniques applied in this sector of crucial importance to the Spanish mining industry were the Lerchs and Grossmann algorithm, parametric analysis and the Milawa algorithm. [Copyright &y& Elsevier]

One of the characteristics of soft rock that contains clay and engineering geology is water swelling and.disintegration. The fractal model of slate disintegration is established by Gate Gaudin Sehuhmann distribution function, representative slate samples are chosen to perform laboratory tests of slaking, and the fractal dimension value of slate disintegration change law with time is obtained. The results show that absorbing water and disintegrating progress of slate is also a progress that fractal dimension of slate scrap change successively, when disintegrating of slate arrived to some extent, grade of scrap of slate disintegrated is no more change, fractal dimension of scrap of slate disintegrated incline to a critical value. The disintegration of slate has lag phenomenon in time. The initial disintegration time and the maximum disintegration fractal dimension of rocks are different because of the different microstructure and material composition. [ABSTRACT FROM AUTHOR]

The accidents caused by the instability of bedding rock slope are often encountered in the expressway construction and operation in China. The shear strength parameters of the structural plane play a major role in controlling the stability of the bedding rock slope. In this paper, in-situ direct shear tests were performed on the structural planes containing the thick muddy interlayer, which were widely distributed between the layers of muddy slate in Guizhou Expressway. A numerical model considering the thickness of the muddy interlayer and the shape of the structural plane is established using the UDEC program. Numerical analysis has been performed to reveal the shear mechanical behaviors and the progressive failure mechanism of the muddy structural plane from a mesoscopic perspective. The thickness of the muddy interlayer has a great influence on the shear mechanical behaviors of the structural planes containing the weak layer. With the increase of the thickness of the interlayer, the peak shear strength of the structural plane decreases, and the stress-displacement curve presents a strong nonlinear characteristic. Due to the uneven spatial distribution of the thickness and morphology of the muddy interlayers in actual engineering practices, it should not only adopt the results from in-situ direct shear tests, but also consider the interlayer thickness for the stability analysis of the bedding rock slope. [ABSTRACT FROM AUTHOR]

J. R. Martin is a leading scholar who has greatly developed the theoretical framework of systemic functional linguistics (SFL) over the past four decades. Some of these contributions, such as the systems of discourse semantics, the appraisal framework and genre relations have been widely applied in various areas of linguistic studies and language education. The educational linguistic model he and his colleagues have cultivated and developed has attracted the attention of more and more educators from different disciplines around the globe. In this interview, he firstly elaborates on the significance of the concepts of discourse semantics, grammatical metaphor and genre. Then he continues with applications of genre theory in secondary school education, language maintenance, the relation and collaboration between Legitimation Code Theory (LCT) and SFL, and how the two paradigms complement each other. Finally, he introduces some of his recent collaborations with grammarians of different languages. [ABSTRACT FROM AUTHOR]

The article reports on the volcanic series of rocks on the southern and eastern flanks of Cader Idris in Harlech, Wales. The volcanic series of rocks of Cader Idris are composed of lavas and ashes with dolerite entry of slaty materials. Their determining factors are presence of lime in plants, existence of dripping water and ledges of good soil on rock-faces. They are dominated by calciferous rock namely pillow-lavas with calcite. They are also made up of acidic rocks with granophyres, rhyolites, ashy slates, mudstones, and dolerites.