Local Earth Research Articles

Crystal structure and magnetic properties of Ba2R2/3TeO6 (R = Y, La, Pr, Nd, Sm–Lu) double perovskites

A new series of cubic double perovskites BaTeO6 (R = Y, La, Pr, Nd, Sm–Lu) was synthesized via solid state reaction. The and ions are ordered on alternating octahedral sites, with the rare earth sites 2/3 occupied to balance the charge. The lattice parameters decrease monotonically from for Ba2TeO6 to for Ba2TeO6. The lattice parameter for R = Y is close to that of Ho. Analysis of the resulting bond lengths indicates a structural relaxation around the R ion site. Ba2TeO6, Ba2TeO6 and Ba2TeO6 show primarily temperature-independent magnetic susceptibility due to the lack of a local rare earth moment. For Ba2TeO6 and Ba2TeO6, the susceptibilities are influenced by Van Vleck-like contributions from excited state multiplets. For the remaining members, the Curie–Weiss law is followed with low-temperature deviations that can be associated with various degrees of crystalline electric field splitting. No magnetic ordering was observed down to 1.8 K in any of the compounds.

Effect of diffusing TbF3 powder on magnetic properties and microstructure transformation of sintered Nd-Fe-Cu-B magnets

The coercivity of sintered Nd-Fe-Cu-B magnets is markedly enhanced from 12.57 to 21.70kOe while the remanence decreases from 13.80 to 13.49kGs by grain boundary diffusion of TbF3 powder for 2h. Microstructure analysis suggests that, during the diffusion process, F diffuses into the magnets easily and forms a new F-rich phase. The enrichment of F in grain boundary near the surface leads to the Cu movement into the interior and the Cu reduction in the surface of magnets. Diffusion of Tb leads to an increase of local total rare earth elements content. Under the combined effect of Cu reduction and increase of local total rare earth elements content, grain growth area is formed and further diffusion is suppressed. That excessive Tb diffuses into matrix phase leads to a decrease in remanence. When the grain growth area is removed, the deterioration of remanence recovers to 13.80kGs without any reduction of coercivity.

A Comparative Review of the Methodologies to Identify a Global Earthing System

International Standards IEC 61936-1 and EN 50522 define a global earthing system (GES) as the earthing network, created by the interconnection of local earthing systems that should guarantee the absence of dangerous touch voltages. Despite that, standards do not provide any official practical guidelines for its identification. The official classification of GES areas would lead to a simplification of the design and verification procedures of medium voltage/low voltage (MV/LV) substations grounding systems with associated economical savings for both distribution system operators and MV users. To overcome this regulatory vacuum, several teams of researchers proposed methods to identify the presence of a GES. In this paper, the main methods developed to identify a GES are presented. The different methodologies are applied to a real urban scenario and compared.

Giant magnetoimpedance effect in a thin-film multilayer meander-like sensor

A meander-like magnetic sensing element based on the giant magnetoimpedance (GMI) effect was prepared by using optical lithography and sputtering deposition techniques. The structure of the sensing element consists of layers of Permalloy (Py = Ni81Fe19), titanium (Ti), and copper (Cu) with composition [Py(100 nm)/Ti(6 nm)]4/Cu(400 nm)/[Py(100 nm)/Ti(6 nm)]4. The GMI was investigated at room temperature under applied magnetic fields (H) varying in the range of ±4.0 kOe in both longitudinal and transversal geometries. The amplitude Iac and frequency f of the ac electrical current were varied in the range of 0.35–6.50 mA and 0.1–20 MHz, respectively. The overall dc electrical resistance of the sensing element was found to be 45.6 Ω. The sensing element yielded a GMI of 53.5% for H≃ 5.0 Oe and f= 7.0 MHz, and the corresponding maximum average sensitivity of about 5 Ω/Oe. The sensing element was used for measuring the local Earth magnetic field (Hlocal=0.26±0.03 Oe) yielding a value close to the one measured by using a Hall sensor probe (=0.23±0.01 Oe). GMI sensors are being used in applications such as accelerometers, magnetometers, biomagnetism, magnetic compasses, traffic control, non-destructive analysis, and virus and cancer cell detection.

Earth construction in Algeria between tradition and modernity

In the south of Algeria, many indigenous settlements have been built using local earth construction techniques; in the north, despite the availability of suitable earth, only a few rural contemporary settlements have been built using ‘improved’ earth construction. This paper adopts a case study approach to examine and compare structural deficiencies of two earth-built housing settlements in different regions in Algeria. In the indigenous earth settlement in the south, where adobe was used in combination with local timber and stones, the dwellings exhibit many structural defects. Stabilisation of the soil and introduction of modern materials in the contemporary rammed earth settlement in the north has not, however, helped produce structurally adequate dwellings. These dwellings also exhibited many cracks and debonding of rendering, and thus did not fulfil the requirements and aspirations of their occupants. The study concludes that for a potentially successful earth building scheme there are inter-related factors that should be considered: selection of an appropriate soil and construction technique, implementation of a suitable structural design, construction and post-completion processes, availability of relevant skills and provision of adequate training on the construction technique.

The Ore Deposit 3D Modelling, New Effective Solution in the Optimization of Geological and Mining Works

Despite its small area, Albania is rich in mineral deposits. One of these is Kçira's copper ore deposit located about 12 km west of Puka. The core tools for developing and mining in local or regional-scale 3D common earth models for the purpose of targeting new ore or specific geologic relationships are now here. It is now incumbent on the industry, with its wealth of knowledge of specific ore forming processes, its rich archive of 3D data sets, and with a definite need to find deeper ore, to capitalize on this new technology to achieve its expected goals, enhancing the mineral targeting process and ultimately increasing mineral wealth. The emerging geo-modelling softwares for automating the model construction process, are leaving the experts free time to interpret and test exploration criteria. Due to the rapid technological change it is easier to process data and create a 3D model of the mineral body, update in real time, also increasing the accuracy of calculating the quantity of metals in the mineral resource. This article treats the 3D modelling of the copper ore using the Maping and General mining software. This method of modelling ore bodies reduces the time and cost for research and exploitation by facilitating the work of geologists, institutions and companies on their respective functions. Geological modelling is a complex sub-discipline of geology which integrates structural geology, sedimentology, paleo climatology, metallogeny, diagenesis etc. The model that we obtain for this mineral deposit (based on implicit and explicit methods) is important because it allows us to calculate and represent accurately the amount of copper metal, in-citu and mining resources.

Influence of LV Neutral Grounding on Global Earthing Systems

International Standards define a Global Earthing System as an earthing net created interconnecting local Earthing Systems (generally through the shield of MV cables and/or bare buried conductors). In Italy, the regulatory authority for electricity and gas requires distributors to guarantee the electrical continuity of LV neutral conductor. This requirement has led to the standard practice of realizing “reinforcement groundings” along the LV neutral conductor path and at users’ delivery cabinet. Moreover, in urban high-load scenarios (prime candidates to be part of a Global Earthing System), it is common that LV distribution scheme creates, through neutral conductors, an effective connection between grounding systems of MV/LV substations, modifying Global Earthing System consistency. The aim of this paper is to evaluate the effect, in terms of electrical safety, of the aforementioned LV neutral distribution scheme when an MV-side fault to ground occurs. For this purpose, simulations are carried out on a realistic urban test case and suitable evaluation indexes are proposed.

The huts of the Rocío-Doñana (Spain): Built heritage: analysis, conservation and maintenance

The El Rocio settlement is a site that originally arose as a religious pilgrimage destination in the 16th century. It lies in an area of high environmental value in the current Donana National Park in the southern Iberian Peninsula. The transformation of these temporary shepherds’ shelters into an established, inhabited site occurred in the 19th century. These huts are built of local vegetation and earth, and have been barely modified to the present day. There are few remaining traditional dwellings in this style, which is why they need strong legal protection and continual maintenance. This work addresses the heritage value of this type of buildings, their relation with traditions and customs, and their influence on the urban landscape. The most notable building components were analysed with the aim of providing ideas and insights for improved conservation. In addition, the changes in construction style of the different hut types are analysed, cataloguing the remaining huts, the need for legal protection, and the maintenance work required.

Major Technologies for Safe Construction of High Earth-Rockfill Dams

Abstract The earth-rockfill dam is one of the primary dam types in the selection of high dams to be constructed in Western China, since it is characterized by favorable adaptability of the dam foundation; full utilization of local earth, rock, and building-excavated materials; low construction cost; and low cement consumption. Many major technical issues regarding earth-rockfill dams with a height of over 250 m were studied and solved successfully in the construction of the 261.5 m Nuozhadu earth core rockfill dam. This paper describes research achievements and basic conclusions; systematically summarizes the accumulated experiences from the construction of the Nuozhadu Dam and other high earth-rockfill dams; and discusses major technical issues, such as deformation control, seepage control, dam slope stability, safety and control of flood discharging, safety and quality control of dam construction, safety assessments, early warning, and other key technical difficulties. This study also provides a reference and technological support for the future construction of 300 m high earth-rockfill dams.

Electrical excitation of the local earth for resonant, wireless energy transfer

Here we demonstrate wireless energy transfer that exploits the conductivity and permittivity of soil to create a potential gradient on the surface around an earthed electrode, distributing electrical energy over the area. This generated surface potential can be amplified using a special standing-wave receiver for harnessing the distributed energy. We have experimentally mapped the surface potential around the electrode and plotted the received energy covering an area of 1200 m2. Key operating parameters are determined with a discussion on optimizing the system efficiency. This technique could address the challenge of distributing electrical energy to many low power devices over large outdoor areas without the use of wires.

Location and source mechanism of the Karlsruhe earthquake of 24 September 2014

On 24 September 2014, a ML 2.3 earthquake occurred southwest of the urban area of Karlsruhe, Germany, which was felt by a few people (maximum intensity I 0 = III). It was the first seismic event in this highly populated area since an I 0 = VII earthquake in 1948. Data of 35 permanent and temporary seismometers were analysed to localise the event and to determine the focal mechanism to compare it to previous seismicity. Restricting the data to P- and S-phases from 18 nearby stations and optimising the local earth model result in an epicentre in the southwest of the city at 48.986°N/8.302°E and in a hypocentral depth of 10 km. To calculate the focal mechanism, 22 P- and 5 SH-polarities were determined that constrain a stable left lateral strike-slip focal mechanism with a minor thrusting component and nodal planes striking NE-SW and NW-SE. The epicentre lies in the vicinity of the I 0 = VII earthquake of 1948. Both events are part of the graben-parallel flower structure beneath the Upper Rhine Graben, parallel to the active Rastatt source zone, which runs 5 km further east and included the epicentre of the 1933 Rastatt I 0 = VII earthquake. The focal mechanisms of the 2014 and 1948 earthquakes show NE-SW striking nodal planes that dip to the southeast. However, for the 1948 event, a normal faulting mechanism was determined earlier. Taking the uncertainty of the epicentre and focal mechanism in 1948 and its fault dimensions into account, both events might have happened on the same fault plane.

Impact of MV Ground Fault Current Distribution on Global Earthing Systems

Global earthing systems (GESs), created by the interconnection of local earthing systems, should guarantee the absence of dangerous touch voltages. One of the reasons for this safety characteristic of GESs is the fault current distribution between grounding electrodes and medium-voltage (MV) cable sheaths: Only a small portion of the fault current is injected into the ground by the ground grid of the faulty substation. In systems with isolated neutral or with resonant earthing, this effect may be sufficient to provide safety from electric shock. In this paper, a model describing the behavior of the MV distribution system with interconnected grounding electrodes during a ground fault is built. It is then used to analyze the impact of different factors on the fault current distribution. A sensitivity analysis is performed, varying the main parameters, and the results are used to draw some conclusions on the current distribution influence on GESs.

Global Earthing System: Can Buried Metallic Structures Significantly Modify the Ground Potential Profile?

Global earthing systems (GESs), which are created by the interconnection of local earthing systems, should guarantee the absence of dangerous touch voltages. According to international standards, one of the reasons for this safety characteristic of GESs is that medium-voltage and low-voltage grounding systems form a quasi-equipotential area. Typical examples of GESs are in city centers due to the high number of interconnected grounding systems in the area. For this reason, in addition to ground grids, other metallic parts with different primary functions shall be also considered, e.g., water and gas pipes, tramway tracks, and building foundations can modify the electric potential distribution in the area. In this paper, a model based on the Maxwell's subareas method (MaSM) is used to evaluate how buried metallic parts, which are not intentionally connected to ground grids, modify the electric potential on the soil surface. First, the MaSM model is validated with experimental measurements on a simple electrode configuration. The measured voltages are compared with the MaSM results and with the results obtained with a finite-element method model simulated with COMSOL Multiphysics. Then, the simulations are carried out on a realistic urban test case.

Cerium anomaly at microscale in fossils.

Patterns in rare earth element (REE) concentrations are essential instruments to assess geochemical processes in Earth and environmental sciences. Excursions in the "cerium anomaly" are widely used to inform on past redox conditions in sediments. This proxy resources to the specificity of cerium to adopt both the +III and +IV oxidation states, while most rare earths are purely trivalent and share very similar reactivity and transport properties. In practical terms, the level of cerium anomaly is established through elemental point quantification and profiling. All these models rely on a supposed homogeneity of the cerium oxidation state within the samples. However, this has never been demonstrated, whereas the cerium concentration can significantly vary within a sample, as shown for fossils, which would vastly complicate interpretation of REE patterns. Here, we report direct micrometric mapping of Ce speciation through synchrotron X-ray absorption spectroscopy and production of local rare earth patterns in paleontological fossil tissues through X-ray fluorescence mapping. The sensitivity of the approach is demonstrated on well-preserved fishes and crustaceans from the Late Cretaceous (ca. 95 million years (Myr) old). The presence of Ce under the +IV form within the fossil tissues is attributed to slightly oxidative local conditions of burial and agrees well with the limited negative cerium anomaly observed in REE patterns. The [Ce(IV)]/[Ce(tot)] ratio appears remarkably stable at the microscale within each fossil and is similar between fossils from the locality. Speciation maps were obtained from an original combination of synchrotron microbeam X-ray fluorescence, absorption spectroscopy, and diffraction, together with light and electron microscopy. This work also highlights the need for more systematic studies of cerium geochemistry at the microscale in paleontological contexts, in particular across fossil histologies.

New paleomagnetic results from Late Ordovician rocks of the Yangtze Block, South China, and their paleogeographic implications

AbstractThe paleogeographic relationship between South China and Australia during the Ordovician is important for understanding the configuration of South China in Gondwana. However, high‐quality Ordovician paleomagnetic results for the Yangtze Block are scarce. Here we report the results of a new paleomagnetic study of the Late Ordovician limestones of Wangcang County in the northern Yangtze Block, performed in order to constrain the paleoposition of South China. Two magnetic components were isolated by detailed stepwise thermal demagnetization. The low‐temperature component falls close to the local current Earth's field direction. The site‐mean direction obtained from the high‐temperature component (HTC) carried by magnetite is D/I = 132.6°/−35.2° (α95 = 3.6°) after bedding correction, yielding a paleomagnetic pole at 45.8°S, 191.3°E (dp = 2.4°, dm = 4.2°). The HTC direction passed reversal and fold tests, and its corresponding pole differs from the available paleomagnetic poles since the Silurian of the South China Block. These results suggest that the remanent magnetization was probably acquired during the earliest stage of sedimentation. The high‐temperature component yields a paleolatitude of 19.5°S, implying that the Yangtze Block was at tropic latitudes during the Late Ordovician. These new and reliable paleomagnetic results bridge the Ordovician data gap and favor the proximity between South China and Australia during the Late Ordovician.

English

Urban ecological systems are characterized by complex interactions among institutional, socio-economic and environmental variables. These interactions often generate complex human-dominated landscapes, which significantly influence effective functioning of local and global earth ecosystems and the services they provide to humans and other life on earth. Changes in ecological conditions that result from human actions in urban areas ultimately affect physical morphology and structural outlook as in the case of the study area. Using Survey Research Design (SRD) via questionnaire administration, observation and personal interview and photo-snaps for data collection, authors investigate the impact of urban growth on the environment as occasioned by the existence of a university; essentially, the effects that the growth has on the ecological system of the community. Findings in the study revealed that urban development affects the spatial heterogeneity of the landscape; especially the patterns of variation in land cover and changes in land use over time. The authors propose that effective monitoring agent to guide the direction and coherence of development in the study area is needed to forestall the haphazard pattern of development that is rampart in the area. Also, a comprehensive master plan is needed for the area coupled with provision of essential services like power supply to facilitate adequate and regular electricity supply in the area. Key words: Urban growth, land-use changes, EKSU.

Diffuse X-ray Background Constraints on Models of the Local Interstellar Medium

There is a flux of soft X-rays (0.07–0.284 keV) of diffuse origin observable over the entire sky. As X-rays of this energy are strongly absorbed by the interstellar medium (ISM), one optical depth is 1019 – 1020 H cm−2, they provide a unique probe of neutral material in the solar vicinity. However, to be an effective probe requires that the distribution of emission be well understood, a requirement that is currently unfulfilled (although progress is being made), with unclear fractions originating in the Galactic halo, Local Hot Bubble, heliosphere, and Earth's magnetosheath. The various available data, their consistency (or lack thereof), and their implications for understanding the very local ISM are briefly discussed.

Carola Lentz. Land, Mobility, and Belonging in West Africa. Bloomington: Indiana University Press, 2013. xiv + 331 pp. List of Illustrations. References. Index. $30.00. Paper.

ANTHROPOLOGY AND SOCIOLOGY Carola Lentz. Land, Mobility, and Belonging in West Africa. Bloomington: Indiana University Press, 2013. xiv + 331 pp. List of Illustrations. References. Index. $30.00. Paper.There is a certain kind of scholar, turning up, it seems, as often in Germanic academies as anywhere, who picks a carefully circumscribed topic, studies it to death .. . and then studies it some more, until it somehow springs back to life. Carola Lentz was already a well-published authority on northern Ghana and on issues of ethnicity when she wrote this book about first-comers and latecomers in this region and in an adjacent part of rural Burkina Faso in the Black Volta region. It is well known, too, that Jack Goody and other ethnographers got there first. Dagara people, among others Lentz describes, will be familiar to readers already acquainted with those Goody called LoWiili and LoDagaba. (Lentz notes the controversy over these terms.) But whereas Goody made his name largely on the breadth of his geographical and topical reach, Lentz's work is distinguished by the intensity of its focus. Not soon is anyone likely to cover her chosen topic and place more thoroughly.The two main ethnic groups studied in this volume are the Sisala and Dagara. Over much of the terrain that is covered, it seems that ancestors of Sisala people got there first and ancestors of Dagara came later, often with Sisala permission. But Dagara tended to invite others to join them in their new settlement, and they grew so quickly in numbers that for many the welcome wore thin. And sometimes the authority that their erstwhile hosts may have extended or conceded with grace was later retracted by their descendants when population densities rose and times grew tougher.This, then, is a study of West African exploratory travel, settlement, and ethnic intermixing. It also looks at conflicting claims by priests over local earth shrines, as well as layers of overrule, not least by European colonial powers who complicated the picture by establishing chiefs in places where such central authorities were not respected or even considered necessary. So alongside earth shrine priests, with fuzzy boundaries over their turf, came new chiefs imposing sharper, more exclusionary ones. Here was a situation tailor made for tensions and power struggles. Often, Lentz is careful to point out, early-comers and latecomers found ways of resolving their differences, and the region has remained a generally peaceful one. But sometimes tensions have erupted into protracted disputes and open fighting.In many ways, oral histories about primacy seem to change in each telling, but Lentz is careful not to overgeneralize and her contentions are grounded. …

Le Passage – an archaeology of spatial transitions

Abstract The author reflects on the usage and development of the zoom ‘passage’ and its various forms from the early cinema of the 1920s to the expanding concept of a scaling zoom towards a Cosmic View (Boerke, 1957) and the usage of cosmic zooms in todays fulldome theatres/ planetariums. Today various zoom effects are being used at daily routine. The navigation inside geographical visualization tools is naturally embedded in our daily media experience while using mobile devices, car navigational tools and other applications. All the more a critical perspective on the impact is needed. This article compares the different techniques used in Google Maps and in Fulldome theatres and argues that the usage of digital geographical tools and their inherent zoom structures change our mind concept of local environments, earth and spatial knowledge.

Selection of consolidants for the polychrome clay sculptures in the Guanyin Temple, Sichuan, China

Keywords: Polychrome clay sculptures of Guanyin TempleConservation materialsSelectionConsolidationMaterial application關鍵詞 :: 觀音寺彩繪泥塑補塑材料篩選加固材料應用