Small Spring Research Articles

Environmental and Structural Effects on Physical Reservoir Computing with Tensegrity

This paper describes the effects of body structures and environments around the bodies on their computational abilities. This type of computation outsourced for body structures is called morphological computation. Physical reservoir computing, which uses the body itself as a neural network-like system, is one approach to this computation. In this research, a tensegrity-like structure, designed by the compressive elements and the tensile elements that are made of springs, is used as a body structure. We demonstrated that the structure has a higher computational ability when the structure is easier to move with a smaller spring constant, or when the structure's input amplitude was set to be smaller. In addition, the environments around the body were shown to have large effects on the computational ability. The results of these previous experiments were summarized into four features. First, the softer body has a higher computational ability. Second, the input amplitude can control the memories of the system. Third, the best input position exists which maximizes the computational ability. Fourth, the environments around the structure have effects on the system and its computational ability. Furthermore, this paper suggests that a parallel link structure (i.e., closed-loop link structure) is a prerequisite for physical reservoir computing, and tensegrity structures have ability to learn different functions at the same time.

First record of subterranean rissoidean gastropod assemblages in Southeast Asia (Mollusca, Gastropoda, Pomatiopsidae)

In February 2017 we investigated several caves and karstic springs in Laos for the presence of underground freshwater gastropod species. We report previously unrecorded freshwater gastropod assemblages in the largest cave in Laos, Tham Khon Dôn, and in the third largest cave, Pha Soung, in Khammouane Province, with single finds in Na Li Cave (Khammouane Province), an unnamed cave near Vieng Thong (Bolikhamsay Province) and a small karst spring near Phonsavan (Xianghouan Province). All 15 species recorded and described herein are new to science. Four species are assigned to the new genusPseudoiglica:P. pseudoiglicasp. n.,P. olsavskyisp. n.,P. kameniarisp. n., andP. phonsavanicasp. n.Three species are assigned to the new genusThamkhondonia:T. mouretisp. n.,T. vacquieisp. n., andT. smidaisp. n.Eight species are assigned to the genusTriculaBenson, 1843:T. valenasisp. n.,T. davisisp. n.,T. spelaeasp. n.,T. lenahanisp. n.,T. reischuetzorumsp. n.,T. phasoungensissp. n.,T. bannaensissp. n., andT. viengthongensissp. n.

First record of subterranean rissoidean gastropod assemblages in Southeast Asia (Mollusca, Gastropoda, Pomatiopsidae)

In February 2017 we investigated several caves and karstic springs in Laos for the presence of underground freshwater gastropod species. We report previously unrecorded freshwater gastropod assemblages in the largest cave in Laos, Tham Khon Dôn, and in the third largest cave, Pha Soung, in Khammouane Province, with single finds in Na Li Cave (Khammouane Province), an unnamed cave near Vieng Thong (Bolikhamsay Province) and a small karst spring near Phonsavan (Xianghouan Province). All 15 species recorded and described herein are new to science. Four species are assigned to the new genusPseudoiglica:P.pseudoiglicasp. n.,P.olsavskyisp. n.,P.kameniarisp. n., andP.phonsavanicasp. n.Three species are assigned to the new genusThamkhondonia:T.mouretisp. n.,T.vacquieisp. n., andT.smidaisp. n.Eight species are assigned to the genusTriculaBenson, 1843:T.valenasisp. n.,T.davisisp. n.,T.spelaeasp. n.,T.lenahanisp. n.,T.reischuetzorumsp. n.,T.phasoungensissp. n.,T.bannaensissp. n., andT.viengthongensissp. n.

Following the Fate of Facilitated Migration In A Small Desert Spring

Human modification of the environment can result in the fragmentation and isolation of natural populations. If isolated populations are small, they may experience higher probabilities of extirpation from genetic, demographic, and environmental effects. One approach for managing fragmented and isolated populations is facilitated migration in which individuals are moved between habitat fragments. Here we report on a study of a single system in which we followed the genetic and population consequences of facilitated migration. We moved a small number of pupfish (Cyprinodon nevadensis pectoralis) from one small spring into another small spring that had become isolated as a consequence of human modification of surface hydrology. We followed the fate of immigrant, resident, and admixed fish over multiple generations using molecular identification of individuals and mark-recapture methods. The mark-recapture data revealed that survival probabilities for admixed individuals were about 20% greater than those for the original resident fish. Furthermore, there was a steady increase in the proportion of admixed individuals, suggesting that immigrant alleles spread through the population consistent with the estimate of relative fitness. Overall, the results suggest facilitated migration can have restorative effects over the course of very few generations, and these results, in the context of other studies, suggest facilitated migration is likely to be an effective strategy for managing populations that have become isolated as a consequence of human modification of landscapes.

Monitoring and reactive-transport modeling of the spatial and temporal variations of the Strengbach spring hydrochemistry

This study focuses on 20 years of hydrochemical monitoring of the small springs that emerge in the experimental granitic catchment of Strengbach (OHGE, France) and the simulation of these data using the KIRMAT code. The data indicate that the Strengbach springs display chemostatic behavior; that is, limited temporal variations were noted in the concentrations of dissolved silica (H4SiO4) and most of the basic cations during the studied period (1987–2010), resulting in relative stability of the global weathering fluxes exported by the springs. Only the Ca2+ concentrations reflect a significant decrease in all the Strengbach springs since 1987, and the variations differ from one spring to another. The modeling results show that the decrease in Ca2+ in the Strengbach springs is due to the response of the water-rock interactions within the bedrock to the variations in the chemical composition of the soil solutions, which were characterized by a significant increase in pH and a decrease in Ca2+ concentrations between 1987 and 2010. The decrease in Ca2+ concentrations seen in the Strengbach springs is controlled by changes in the apatite dissolution rate and the compositions of clay minerals induced by the soil solution changes. The differences observed between the Ca2+ trends of the springs are related to changes in the residence time of the water supplying the different springs. The weak impact of the soil solution modifications on the dissolution rates of other primary minerals and on the bulk precipitation rates of the clay minerals explains the relative stability over time of the concentrations of the other cations and dissolved silica in the water derived from the Strengbach springs. Further, the hydrochemical simulations suggest that the chemostatic behavior of the Strengbach springs cannot be explained by the mobilization of waters that are close to chemical equilibrium, but rather by a hydrological control of the spring water residence times. Finally, a comparison of current and long-term weathering rates determined from the spring water monitoring and a regolith profile shows that the modern chemical fluxes of Ca2+ are higher than the long-term ones, whereas the weathering fluxes of H4SiO4 and Na+ have likely been much more stable over time. All of these results indicate that the silicate weathering processes are characterized by weak spatial and temporal variability in the Strengbach catchment, while the chemical elements such as Ca2+, for which the budget in the spring waters is controlled by the dynamic behavior of clay minerals and minor minerals such as apatite, are significantly affected by Quaternary climatic variations and decennial environmental changes.

Impact of topography, climate and moisture sources on isotopic composition (δ18O &δD) of rivers in the Pyrenees: Implications for topographic reconstructions in small orogens

Understanding how orogenic topography controls the spatial distribution and isotopic composition of precipitation is critical for paleoaltitudinal reconstructions. Here, we determine the isotopic composition (δ18O and δD) of 82 small rivers and springs from small catchments in the Pyrenees. Calculation of the deuterium excess (d-excess) parameter allows the distinction of four distinct isotopic provinces with d-excess values of between 15 and 22‰ in the northwest, between 7 and 14‰ in the central northern Pyrenees and between 3 and 11‰ in the northeast. The southern Pyrenees have a homogenous d-excess signature ranging from 7 to 14‰. Our results show significant local moisture recycling and/or rain amount effect in the northwestern Pyrenees, and control by evaporation processes during rainfall events in the southern Pyrenees and for low elevated samples of the northeast of the range. Based on the distribution of d-excess values, we estimate contrasting isotope lapse rates of −2.9/−21.4‰/km (δ18O/δD) in the northwest, −2.7/−21.4‰/km (δ18O/δD) in the north central and −3.7/−31.7‰/km (δ18O/δD) in the northeastern Pyrenees. The southern Pyrenees show distinctly higher lapse rates of −9.5/−77.5‰/km (δ18O/δD), indicating that in this area the altitudinal effect in not the only parameter driving isotopic composition of rivers. Despite their relatively low topographic gradient, the Pyrenees exert a direct control on the isotopic composition of river waters, especially on their northern side. The variations in isotopic composition–elevation relationships documented along the strike of the range are interpreted to reflect an increasing continentality effect driven by wind trajectories parallel to the range, and mixing with Mediterranean air masses. Despite these effects, the measurable orographic effect on precipitation in the Pyrenees proves that the isotopic composition approach for reconstructing past topography is applicable to low-elevation orogens.

Groundwater origin and recharge in the hyperarid Cordillera de la Costa, Atacama Desert, northern Chile

The Cordillera de la Costa is located along the coastline of northern Chile, in the hyperarid Atacama Desert area. Chemical and isotopic analyses of several small coastal springs and groundwater reservoirs between 22.5 °S and 25.5 °S allow understanding groundwater origin, renewal time and the probable timing of recharge. The aquifers are mostly in old volcanic rocks and alluvial deposits. All spring waters are brackish, of the sodium chloride type due to intensive concentration of precipitation due aridity and for deep groundwater to additional water-rock interaction in slowly renewed groundwater and mixing with deep seated brines. The heavy δ18O and δ2H values in spring water are explained by recharge by the arrival of moist air masses from the Pacific Ocean and the originally lighter values in the deep wells can be associated to past recharge by air masses coming from the Atlantic Ocean. Current recharge is assumed almost nil but it was significant in past wetter-than-present periods, increasing groundwater reserves, which are not yet exhausted. To explain the observed chloride content and radiocarbon (14C) activity, a well-mixed (exponential) flow model has been considered for aquifer recharge. The average residence time of groundwater feeding the springs has been estimated between 1 and 2kyr, up to 5kyr and between 7 and 13kyr for deep well water, assuming that current recharge is much less than during the previous wetter period. The recharge period feeding the coastal springs could have been produced 1 to 5kyr BP, when the area was already inhabited, and recharge in the Michilla mine was produced during the 10 to 14.5kyr BP CAPE (Central Andean Pluvial Event) pluvial events of the central Andes. The approximate coincidence of turnover time with the past wet periods, as revealed by paleoclimate data, points to significant recharge during them.

Review: The distribution, flow, and quality of Grand Canyon Springs, Arizona (USA)

An understanding of the hydrogeology of Grand Canyon National Park (GRCA) in northern Arizona, USA, is critical for future resource protection. The ~750 springs in GRCA provide both perennial and seasonal flow to numerous desert streams, drinking water to wildlife and visitors in an otherwise arid environment, and habitat for rare, endemic and threatened species. Spring behavior and flow patterns represent local and regional patterns in aquifer recharge, reflect the geologic structure and stratigraphy, and are indicators of the overall biotic health of the canyon. These springs, however, are subject to pressures from water supply development, changes in recharge from forest fires and other land management activities, and potential contamination. Roaring Springs is the sole water supply for residents and visitors (>6 million/year), and all springs support valuable riparian habitats with very high species diversity. Most springs flow from the karstic Redwall-Muav aquifer and show seasonal patterns in flow and water chemistry indicative of variable aquifer porosities, including conduit flow. They have Ca/Mg-HCO3 dominated chemistry and trace elements consistent with nearby deep wells drilled into the Redwall-Muav aquifer. Tracer techniques and water-age dating indicate a wide range of residence times for many springs, supporting the concept of multiple porosities. A perched aquifer produces small springs which issue from the contacts between sandstone and shale units, with variable groundwater residence times. Stable isotope data suggest both an elevational and seasonal difference in recharge between North and South Rim springs. This review highlights the complex nature of the groundwater system.

Adult tiger spiketail (Cordulegaster erronea Hagen) habitat use and home range observed via radio-telemetry with conservation recommendations

The Tiger Spiketail dragonfly (Cordulegaster erronea Hagen) is geographically restricted to the eastern half of North America, patchily distributed within the range and a habitat specialist of small spring and seepage fed headwater streams running through mature forest. These habitats are highly sensitive to disturbance and the Tiger Spiketail is of conservation concern throughout most of its range. Yet little is known about the habitat use of either sex away from the breeding stream hampering conservation strategies. In this study we use miniaturized radio transmitters to investigate the habitat use and home range of individual males and a female Tiger Spiketail in New Jersey. This is the first and only radio-telemetry for this species. We also provide recommendations for habitat protection and conservation. Our studies demonstrate that this species is critically dependent upon mature forest and the high quality, perennial headwater streams that run through them. These habitats are particularly sensitive to disturbance. Except when patrolling and ovipositing, both sexes are in the canopy above the breeding stream and in the adjacent mature forest, indicating the inseparable linkage between the aquatic and forested terrestrial habitat for this species. Our observations also suggest that C. erronea occurs in a metapopulation of nearby streams in our study area. Conservation of this species may therefore require forest protection far beyond the breeding stream. In New Jersey, and in other places throughout the range, there are many potential pressures on these habitats and current regulatory protections are not likely suitable. These same habitats may also be important for other Odonate species of conservation concern suggesting that protection of C. erronea may benefit a suite of species. We hope the information obtained from this study can assist resource managers in developing conservation and habitat protection measures.

Two new species of Hyalella (Crustacea, Amphipoda, Hyalellidae) from state of Rio Grande do Sul, Southern Brazil.

There are 68 known species of Hyalella worldwide, with 23 occurring in Brazil. The state of Rio Grande do Sul, Southern Brazil, has the largest diversity of the genus in the country, with nine species recorded. The current study aimed to describe two new species of Hyalella from state of Rio Grande do Sul, both of them in the Northwest region of the state, one found in a small spring and another in an artificial pond. Hyalella georginae n. sp. presents several clusters of simple setae on antenna 2, maxilliped very slender, gnathopod 2 dactylus not reaching the lobe of propodus, pleopods rami with short plumose setae and a peculiar pattern of setae on uropods and telson. Hyalella gauchensis n. sp. presents antenna 2 with few setae, maxilliped very slender, gnathopod 2 dactylus reaching the lobe of propodus and pleopods rami with long plumose setae. From this work, the number of Hyalella species found in Brazil increases to 25 and 70 for the genus.

Genome-scale data reveal that endemic Poecilia populations from small sulphidic springs display no evidence of inbreeding.

Populations with limited ranges can be highly vulnerable to changes in their environment and are, thus, of high conservation concern. Populations that experience human-induced range reductions are often highly inbred and lack genetic diversity, but it is unknown whether this is also the case for populations with naturally small ranges. The fishes Poecilia sulphuraria (listed as critically endangered) and Poecilia thermalis, which are endemic to small hydrogen sulphide-rich springs in southern Mexico, are examples of such populations with inherently small habitats. We used geometric morphometrics and population genetics to quantify phenotypic and genetic variation within and among two populations of P.sulphuraria and one population of P.thermalis. Principal component analyses revealed phenotypic and genetic differences among the populations. Evidence for inbreeding was low compared to populations that have undergone habitat reduction. The genetic data were also used to infer the demographic history of these populations to obtain estimates for effective population sizes and migration rates. Effective population sizes were large given the small habitats of these populations. Our results imply that these three endemic extremophile populations should each be considered separately for conservation purposes. Additionally, this study suggests that populations in naturally small habitats may have lower rates of inbreeding and higher genetic diversity than expected, and therefore may be better equipped to handle environmental perturbations than anticipated. We caution, however, that the inferred lack of inbreeding and the large effective population sizes could potentially be a result of colonization by genetically diverse ancestors.

Benchmark of the Compactness Potential of Adjustable Stiffness Mechanisms

The VariLeg is an exoskeleton allowing a paraplegic to walk. It was used for competing on an obstacle course at the first Cybathlon. It integrates an adjustable stiffness in the knee joint to improve the walking performance. However, the adjustable stiffness mechanism (ASM) of the VariLeg is bulky and heavy, which hampers the handling of the exoskeleton. Hence, the choice of an ASM concept that only needs small springs is essential. This study benchmarks six state-of-the-art ASMs regarding their needed energy storage capacity, thus their potential for a high compactness. The benchmark is performed with the requirements of the VariLeg and a second requirements set, which can be fulfilled by all six ASMs. The benchmark can be transferred to other requirements as well. It is based on models of the ASMs with their design parameters optimized for the given requirements set. The benchmark reveals large differences between the performances of the investigated ASM concepts of up to a factor of five in the energy storage capacity. This compactness benchmark is a useful design tool to choose a suitable mechanism to realize a compact implementation. More compact ASMs will improve the handling of assistive robots with a physically adjustable stiffness, such as the VariLeg, to support handicapped people in everyday life.

Variability in the mechanisms controlling Southern Ocean phytoplankton bloom phenology in an ocean model and satellite observations

AbstractA coupled global numerical simulation (conducted with the Community Earth System Model) is used in conjunction with satellite remote sensing observations to examine the role of top‐down (grazing pressure) and bottom‐up (light, nutrients) controls on marine phytoplankton bloom dynamics in the Southern Ocean. Phytoplankton seasonal phenology is evaluated in the context of the recently proposed “disturbance‐recovery” hypothesis relative to more traditional, exclusively “bottom‐up” frameworks. All blooms occur when phytoplankton division rates exceed loss rates to permit sustained net population growth; however, the nature of this decoupling period varies regionally in Community Earth System Model. Regional case studies illustrate how unique pathways allow blooms to emerge despite very poor division rates or very strong grazing rates. In the Subantarctic, southeast Pacific small spring blooms initiate early cooccurring with deep mixing and low division rates, consistent with the disturbance‐recovery hypothesis. Similar systematics are present in the Subantarctic, southwest Atlantic during the spring but are eclipsed by a subsequent, larger summer bloom that is coincident with shallow mixing and the annual maximum in division rates, consistent with a bottom‐up, light limited framework. In the model simulation, increased iron stress prevents a similar summer bloom in the southeast Pacific. In the simulated Antarctic zone (70°S–65°S) seasonal sea ice acts as a dominant phytoplankton‐zooplankton decoupling agent, triggering a delayed but substantial bloom as ice recedes. Satellite ocean color remote sensing and ocean physical reanalysis products do not precisely match model‐predicted phenology, but observed patterns do indicate regional variability in mechanism across the Atlantic and Pacific.

Design and analysis of Outside-Deployed Lamina Emergent Joint (OD-LEJ)

Lamina emergent mechanisms (LEMs) can be fabricated in plane, while achieve motion that emerges out of fabrication plane. This paper presents a new flexure hinge called Outside-Deployed Lamina Emergent Joint (OD-LEJ) with a small equivalent spring constant and a large angular displacement. The closed-form model is given and a finite element analysis (FEA) model is created. The FEA results show that this joint can achieve nearly 170.17˚ of rotation without plastic deformation. Stress analysis is done and the results gotten from theoretical calculation and FEA coincide with each other very well. Safety analysis and fatigue analysis are done as well. An Inside-Deployed Lamina Emergent Joint (ID-LEJ) is also proposed. The joint is analyzed through FEA and theoretical calculation. The joint shows a similar bending property as OD-LEJ. Comparisons between these two joints and Lamina Emergent Torsional (LET) joint are made. OD-LEJ and ID-LEJ do better than LET joint in large angular displacement and have a smaller equivalent spring constant. Finally, the movement of the center of rotation and some other problems are discussed.

Correlations between rock and water characteristics of the Inferior Oolite aquifer, central Cotswolds, UK

This study documents the results of an intensive sampling campaign of Jurassic Lower Inferior Oolite limestone and spring water along the lower River Frome valley, near Stroud, in the Cotswold Hills, UK. Our dataset includes discharge measurements from 25 small springs (ranging from 0.04 to 0.71Ls−1), and evaluations of water pH and hardness (dissolved CaCO3) at 15 of these springs. Where possible, samples of in situ limestone were extracted from the spring outcrops, resulting in 30 measurements of local porosity, permeability, and hydraulic conductivity, which were conducted in the laboratory. There exist striking positive correlations between spring discharge and local limestone porosity, and between discharge and water hardness. X-ray diffraction and thin section analyses revealed the important role of rock mineralogy and texture, which may influence the porosity and permeability of the limestones. Samples taken from the eastern side of the valley showed greater degrees of secondary diagenesis, the products of which reduce effective porosity, providing a possible explanation for the depressed values of spring discharge there. In the study area, springs with higher discharges correlated strongly with higher spring water hardness and bedrock porosity. This suggests that water from the limestone matrix may contribute to the springs.

Functional relevance of the small muscles crossing the ankle joint – the bottom-up approach

It has been suggested that increasing muscle strength could help reducing the frequency of running injuries and that a top-down approach using an increase in hip muscle strength will result in a reduced range of movement and reduced external moments at the knee and ankle level. This paper suggests, that a bottom-up approach using an increase of strength of the small muscles crossing the ankle joint, should reduce movement and loading at the ankle, knee and hip. This bottom-up approach is discussed in detail in this paper from a conceptional point of view. The ankle joint has two relatively “large” extrinsic muscles and seven relatively small extrinsic muscles. The large muscles have large levers for plantar-dorsi flexion but small levers for pro-supination. In the absence of strong small muscles the large muscles are loaded substantially when providing balancing with respect to pro-supination. Specifically, the Achilles tendon will be loaded in this situation asymmetrically with high local stresses. Furthermore, a mechanical model with springs shows that (a) the amplitude of the displacement with the strong small springs is smaller and (b) that the loading in the joints of the springs is substantially smaller for the model with the strong small springs. Additionally, strong and active small muscles crossing the ankle joint provide stability for the ankle joint (base). If they are weak, forces in the ankle, knee and hip joint increase substantially due to multiple co-contractions at the joints. Finally, movement transfer between foot and tibia is high for movements induced from the bottom and small for movements induced from the top. Based on these considerations one should speculate that the bottom-up approach may be substantially more effective in preventing running injuries than the top down approach. Various possible strategies to strengthen the small muscles of the ankle joint are presented.

SPRINGS (CLASSIFICATION, FUNCTION, CAPTURING)

Todd, K (1980) proposed the following definition for springs: “a concentrated discharge of groundwater that emerges on the ground as a stream of water that flows freely”. Spring is distinguished from water leak that is a normally diffused but extended (linear or 2D) slower movement of groundwater towards the ground surface. Uprush is every groundwater emergence on the ground surface or through the bed of water bodies (river, lake, sea). In the context of hydrogeology springs and uprushes in general are in fact “overflows” of aquifers; hence they serve as aquifer discharge mechanisms. Springs emerge at the cross section of groundwater level with the topographic relief. Springs are a strong evidence of rich groundwater potential. A big number of small springs emerging at the margins of basins or the hill slopes are an evidence of a shallow aquifer of low hydraulic conductivity. On the contrary, big springs emerging at the bottom of valleys, i.e. the basic geomorphological level, are an indication of a high potential aquifer characterized by considerable values of hydraulic conductivity.

Analysis of Bridge Foundation Damage in Albania

Albania is a mountain-hill territory with many water currents such as rivers, small springs, etc. Therefore, the use of various bridge structures such as wood, metal, reinforced concrete, and suspension has been crucial for the realization of road connections as solution for passage. Political changes over the last 26 years have been accompanied by discordance in the implementation of existing norms and construction maintenance regulations, with a tentative to implement the Eurocodes together with the old Albanian codes. The problems created by this confusion were worsened by natural and human interference causing foundation damage to the bridge structures in Albania. These problems have mainly been investigated following river fence destructions, flooding, earthquake, and landslide activities. In this paper we have the goal to perform damage analysis on some bridges by following the method of geological and climatic investigations accompanied by human activity impact that could be their cause of damage. The main natural factors contributing to the damage of bridge foundations are geological and hydrogeological conditions, erosion, and alteration while the human factors are river bed excavation close to the bridge foundations, damage of river fences, and uncontrolled industrial waste discharge. As a result some recommendation on the solution of damage will be introduced.

Environmental issues of the Island of Giglio, Tuscan Archipelago, Italy

The Island of Giglio consists of the lower Pliocene monzogranite intrusion (91.5% of the territory) and Mesozoic–lower Miocene metamorphic and sedimentary tectonic units (8.5% of the territory) of the Ligurian-Piemontese and Tuscan domains in the Franco Promontory. Climatic data recorded from 1993 to 2015 highlight that the average annual temperature and rainfall have increased overall. The main morphological characteristics of the island are: (1) the landslides that affect either the geological formations, above all along the coastal belt, in particular in the Franco Promontory, or the widespread eluvium–colluvium deposits and numerous piles of rock blocks originating from the monzogranite intrusion; (2) the several torrents that cut across the monzogranite intrusion with high gradients resulting in considerable erosion. The island, which includes some very small perennial springs, is covered mainly by short brush and garrigue and subordinately by forests. Six environmental issues have been detected: the high geomorphological and hydraulic risk, respectively, along the coastline, and in the urban areas of Cala delle Cannelle, Giglio Campese, and Giglio Porto; the abandoned quarries showing unstable fronts; the landfill of municipal solid waste, lacking remediation aimed at its safety; the protection and set up of the perennial springs; the safety of paths; and the mining of pyrite started in 1875 until the closure of works in 1962. Suitable suggestions to solve the environmental issues are provided.

Direct transduction method for measuring the ultrasonic attenuation in Si(111) in the frequency range 100 MHz–1 GHz

Abstract A direct ultrasonic transduction method was investigated as a function of frequency in order to evaluate the ultrasonic attenuation in doped n-type Si(111) by using a setup where an incorporated small spring acts as an adjustable coil. Measurements were performed in the frequency range from 100 MHz to 1 GHz using an AlN transducer produced directly on the Si sample. A vector network analyzer (VNA) was used to record the acoustic reflections. Dependence of the generated wave central frequency on transducer thickness, active area and circuit impedance was examined. One-dimensional (1D) simulations using an equivalent electrical circuit were carried out to validate the VNA measurements. An overall agreement was observed. The wave attenuation in the highly doped n-type Si(111) was found to have a quadratic dependance on the frequency.