Sphagnum reintroduction under a warming climate: keys to success

2020 ◽  
Author(s):  
Juul Limpens ◽  
Hilde Tomassen
Keyword(s):  
Water Table ◽  
Position Control ◽  
Water Type ◽  
Nurse Plants ◽  
Species Reintroduction ◽  
Warming Climate ◽  
Species Mixture ◽  
Long Time ◽  
Bare Peat ◽  
Mulch Cover

<p>Restoring peatland functioning is closely related to restoring growth of ecosystem engineering Sphagnum species. In strongly degenerated peatlands reintroducing diaspores of Sphagnum is necessary to overcome strong dispersal and establishment bottlenecks. Which reintroduction strategy varies between peatland types, surface properties and/or microclimate. Comparative analyses of restoration techniques is scarce, hampering informed management choices.    </p><p>We set out to assess keys to success for Sphagnum reintroduction on strongly humified bare peat in three degraded and long-time rewetted temperate peatlands in the Netherlands. To this end we experimentally manipulated water table position (control, extra water), type of abiotic shelter (control, nurse plants, mulch), Sphagnum species (S. magellanicum, S. papillosum and S. cuspidatum), species mixture (monoculture, mixed culture), diaspore size (clumped intact plants or fragments) and diaspore density (0, 36, 72, 156 plants/m<sup>2</sup>) and monitored Sphagnum survival, lateral expansion and environmental conditions. The experiment was established in 2018 and repeated in 2019, covering two of the most extreme summers in recorded history.</p><p>Water table close to the surface and shelter of a mulch layer were key to Sphagnum survival and growth irrespective of Sphagnum species, reintroduction method or year. Survival increased linearly with diaspore density. Diaspore size showed an interaction with mulch cover: fragments did best under mulch cover, whereas clumped plants survived better outside shelter.</p><p>Taken together our results suggest that successful reintroduction of Sphagnum is possible under a warming climate, but that strategies should be strongly focussed on amelioration of abiotic stress even when water tables are close to the surface. </p>

Warming climate forcing impact from a sub-arctic peatland as a result of late Holocene permafrost aggradation and initiation of bare peat surfaces

2021 ◽  
Vol 264 ◽  
pp. 107022
Author(s):  
Minna Väliranta ◽  
Maija E. Marushchak ◽  
Juha-Pekka Tuovinen ◽  
Annalea Lohila ◽  
Christina Biasi ◽  
...  
Keyword(s):  
Late Holocene ◽  
Climate Forcing ◽  
Warming Climate ◽  
Bare Peat

scholarly journals Construct and control of feet gait mechanisms for walking training

2018 ◽  
Vol 192 ◽  
pp. 02009
Author(s):  
Warawut Suwalai
Keyword(s):  
Position Control ◽  
Tracking Error ◽  
Gait Training ◽  
Gait Pattern ◽  
Stroke Patients ◽  
Pid Algorithm ◽  
Long Time ◽  
Rotational Actuator ◽  
And Control

Gait training or gait rehabilitation is one of the major physiotherapy for stroke patients. Evidently, the robot-assisted gait training, as one part of medical technology innovation breakthrough, has important role in the rehabilitation process. The robot effectively improves treatment outcomes, fast recovery time and better convenience from traditional treatment. Typically, stroke patients are trained to walk on treadmill while a physiotherapist carefully supports and re-correct the gait pattern of the patient. For repetitive and long-time rehabilitation, it is so difficult that the physiotherapist can maintain the quality of treatment consistently. To solve such difficulties, the robotic platform is proposed for automatic guiding the gait pattern for ankle rehabilitation. The robot consists of left and right sides. Each of them is actuated by two linear and one rotational actuator. PID algorithm is implemented for position control of each joint. The experimental results show the tracking error in non-loaded and loaded cases.

scholarly journals Geostatistical investigation into the temporal evolution of spatial structure in a shallow water table

2006 ◽  
Vol 10 (1) ◽  
pp. 113-125 ◽  
Author(s):  
S. W. Lyon ◽  
J. Seibert ◽  
A. J. Lembo ◽  
M. T. Walter ◽  
T. S. Steenhuis
Keyword(s):  
Spatial Structure ◽  
Shallow Water ◽  
Water Table ◽  
Indicator Kriging ◽  
Time Interval ◽  
Short Time Interval ◽  
Soft Data ◽  
Shallow Water Table ◽  
Hard Data ◽  
Long Time

Abstract. Shallow water tables near-streams often lead to saturated, overland flow generating areas in catchments in humid climates. While these saturated areas are assumed to be principal biogeochemical hot-spots and important for issues such as non-point pollution sources, the spatial and temporal behavior of shallow water tables, and associated saturated areas, is not completely understood. This study demonstrates how geostatistical methods can be used to characterize the spatial and temporal variation of the shallow water table for the near-stream region. Event-based and seasonal changes in the spatial structure of the shallow water table, which influences the spatial pattern of surface saturation and related runoff generation, can be identified and used in conjunction to characterize the hydrology of an area. This is accomplished through semivariogram analysis and indicator kriging to produce maps combining soft data (i.e., proxy information to the variable of interest) representing general shallow water table patterns with hard data (i.e., actual measurements) that represent variation in the spatial structure of the shallow water table per rainfall event. The area used was a hillslope in the Catskill Mountains region of New York State. The shallow water table was monitored for a 120 m×180 m near-stream region at 44 sampling locations on 15-min intervals. Outflow of the area was measured at the same time interval. These data were analyzed at a short time interval (15 min) and at a long time interval (months) to characterize the changes in the hydrologic behavior of the hillslope. Indicator semivariograms based on binary-transformed ground water table data (i.e., 1 if exceeding the time-variable median depth to water table and 0 if not) were created for both short and long time intervals. For the short time interval, the indicator semivariograms showed a high degree of spatial structure in the shallow water table for the spring, with increased range during many rain events. During the summer, when evaporation exceeds precipitation, the ranges of the indicator semivariograms decreased during rainfall events due to isolated responses in the water table. For the longer, monthly time interval, semivariograms exhibited higher sills and shorter ranges during spring and lower sills and longer ranges during the summer. For this long time interval, there was a good correlation between probability of exceeding the time-variable median water table and the soil topographical wetness index during the spring. Indicator kriging incorporating both the short and long time interval structure of the shallow water table (hard and soft data, respectively) provided more realistic maps that agreed better with actual observations than the hard data alone. This technique to represent both event-based and seasonal trends incorporates the hillslope-scale hydrological processes to capture significant patterns in the shallow water table. Geostatistical analysis of the spatial and temporal evolution of the shallow water table gives information about the formation of saturated areas important in the understanding hydrological processes working at this and other hillslopes.

Economical, Efficient and Optimum Design of Storm Water Harvester

GIS Business ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 187-193
Author(s):  
Deepak Juneja ◽  
Aditya Rana
Keyword(s):  
Water Table ◽  
Water Demand ◽  
Filter Material ◽  
Storm Water ◽  
Water Harvesting ◽  
Run Off ◽  
Daunting Task ◽  
Long Time ◽  
Rate Of Decline ◽  
Optimum Solution

 In most parts of India, water table is getting lowered. The problem is more predominant in dense cities. Some cities have become dependent on potable water supply. Due to paving of roads and construction of buildings, Infiltration has reduced and run off has increased. Run off increases when the rainfall is intense and with increased road and building infrastructure. Further there is huge withdrawal of water to meet the demand for growing population. Sowing of paddy to increase the returns from farming adds to the problem. Paddy needs 150cm of water from sowing to harvesting. It is not the natural crop of this region. Part of this water demand is met by monsoon and the rest by pumping out of water. There is huge and rapid withdrawal of water from tube wells to keep the crops inundated in water. This causes the drawdown or lowering of water table.  In the last two decades water has been receding at the rate of 50-100cm per year. After concerns of water harvesting were raised, the rate of decline has receded. Since we cannot do much about reducing water demand, the solution lies in water harvesting and recycling waste water. Roof top water harvesting is easy and has no challenges. Storm water harvesting is challenging and daunting task. The harvesters get clogged and may not be operational for long time. Optimum solution has been found for filter material to be used, and design of harvester.

scholarly journals Evaluating integrated surface/subsurface permafrost thermal hydrology models in ATS (v0.88) against observations from a polygonal tundra site

2019 ◽  
Author(s):  
Ahmad Jan ◽  
Ethan T. Coon ◽  
Scott L. Painter
Keyword(s):  
Water Table ◽  
Flow Direction ◽  
Meteorological Data ◽  
Three Dimensional ◽  
Soil Evaporation ◽  
Model Parameters ◽  
Field Observations ◽  
Evaporation Model ◽  
Warming Climate ◽  
Ice Wedge

Abstract. Numerical simulations are essential tools for understanding the complex hydrologic response of Arctic regions to a warming climate. However, strong coupling among thermal and hydrological processes on the surface and in the subsurface and the significant role that subtle variations in surface topography have in regulating flow direction and surface storage lead to significant uncertainties. Careful model evaluation against field observations is thus important to build confidence. We evaluate the integrated surface/subsurface permafrost thermal hydrology models in the Advanced Terrestrial Simulator (ATS) against field observations from polygonal tundra at the Barrow Environmental Observatory. ATS couples a multiphase, three-dimensional representation of subsurface thermal hydrology with representations of overland nonisothermal flows, snow processes, and surface energy balance. We simulated thermal hydrology of three-dimensional ice-wedge polygons with generic but broadly representative surface microtopography. The simulations were forced by meteorological data and observed water table elevations in ice-wedge polygon troughs. With limited calibration of parameters appearing in the soil evaporation model, the three-year simulations agreed reasonably well with snow depth, summer water table elevations in the polygon center, and high-frequency soil temperature measurements at several depths in the trough, rim, and center of the polygon. Upscaled evaporation is in good agreement with flux tower observations. The simulations were found to be sensitive to parameters in the bare soil evaporation model, snowpack, and the lateral saturated hydraulic conductivity. The study provides new support for an emerging class of integrated surface/subsurface permafrost simulators, and provides an optimized set of model parameters for use in watershed-scale projections of permafrost dynamics in a warming climate.

scholarly journals Geostatistical investigation into the temporal evolution of spatial structure in a shallow water table

2005 ◽  
Vol 2 (4) ◽  
pp. 1683-1716 ◽  
Author(s):  
S. W. Lyon ◽  
J. Seibert ◽  
A. J. Lembo ◽  
M. T. Walter ◽  
T. S. Steenhuis
Keyword(s):  
Spatial Structure ◽  
Shallow Water ◽  
Water Table ◽  
Indicator Kriging ◽  
Time Interval ◽  
Short Time Interval ◽  
Soft Data ◽  
Shallow Water Table ◽  
Hard Data ◽  
Long Time

Abstract. Shallow water tables in the near-stream region often lead to saturated areas in catchments in humid climates. While these saturated areas are assumed to be of importance for issues such as non-point pollution sources, little is known about the spatial and temporal behavior of shallow water tables and the resulting saturated areas. In this study, geostatistical methods are employed demonstrating their utility in investigating the spatial and temporal variation of the shallow water table for the near-stream region. Event-based and seasonal changes in the spatial structure of the shallow water table, which directly influences surface saturation and runoff generation, can be identified and used in conjunction to characterize the hydrology of an area. This is accomplished through semivariogram analysis and indicator kriging to produce maps combining supplemental soft data (i.e., proxy information to the variable of interest) representing seasonal trends in the shallow water table with hard data (i.e., the actual measurements) that represent variation in the spatial structure of the shallow water table per rainfall event. The area used was a hillslope located in the Catskill Mountains region of New York State. The shallow water table was monitored for a 120 m×180 m near-stream region at 44 sampling locations on 15-min intervals. Outflow of the area was measured at the same time interval. These data were analyzed at a short time interval (15 min) and at a long time interval (months) to characterize the changes in the hydrology of the region. Indicator semivariograms based on transforming the depth to ground water table data into binary values (i.e., 1 if exceeding the time-variable median depth to water table and 0 if not) were created for both time interval lengths. When considering only the short time interval, the indicator semivariograms for spring when there is excess rainfall show high spatial structure with increased ranges during rain events with surface saturation. During the summer, when evaporation exceeds precipitation, the ranges of the indicator semivariograms decrease during rainfall events due to isolated responses in the water table. When summarized over a longer, monthly time interval, semivariograms exhibited higher sills and shorter ranges during spring and lower sills and longer ranges during the summer. For this long time interval analysis, there was a good correlation between probability of exceeding the time-variable median water table and the soil topographical wetness index during the spring. Indicator kriging incorporating both the short and long time interval structure of the shallow water table (hard and soft data, respectively) provided more realistic maps that agreed better with actual observations then traditional hard data alone. This technique to represent both event-based and seasonal trends compensates for spatially sparse observations while incorporating physical hydrology of the hillslope to capture significant patterns in the shallow water table. Geostatistical analysis of the spatial and temporal evolution of the shallow water table gives information about the formation of saturated areas important in the understanding hydrological processes working at this and other hillslopes.

200kv superconducting cryo electron microscope

1987 ◽  
Vol 45 ◽  
pp. 642-643
Author(s):  
M. Iwatsuki ◽  
Y. Kokubo ◽  
Y. Harada ◽  
J. Lehman
Keyword(s):  
Electron Microscope ◽  
Structure Analysis ◽  
Organic Materials ◽  
Strong Interactions ◽  
Specimen Preparation ◽  
Great Effort ◽  
Electron Microscopic ◽  
Crystal Fields ◽  
Special Skill ◽  
Long Time

In recent years, the electron microscope has been significantly improved in resolution and we can obtain routinely atomic-level high resolution images without any special skill. With this improvement, the structure analysis of organic materials has become one of the interesting targets in the biological and polymer crystal fields.Up to now, X-ray structure analysis has been mainly used for such materials. With this method, however, great effort and a long time are required for specimen preparation because of the need for larger crystals. This method can analyze average crystal structure but is insufficient for interpreting it on the atomic or molecular level. The electron microscopic method for organic materials has not only the advantage of specimen preparation but also the capability of providing various information from extremely small specimen regions, using strong interactions between electrons and the substance. On the other hand, however, this strong interaction has a big disadvantage in high radiation damage.

A Stationary Solution of High-Energy Electron Reflection (HEER) for An Arbitrary Surface

1990 ◽  
Vol 48 (2) ◽  
pp. 374-375
Author(s):  
YIQUN MA
Keyword(s):  
Stationary Solution ◽  
High Energy ◽  
Bloch Wave ◽  
Dynamical Theory ◽  
High Energy Electron ◽  
Bulk Materials ◽  
Periodic Surface ◽  
Electron Transmission ◽  
Electron Reflection ◽  
Long Time

For a long time, the development of dynamical theory for HEER has been stagnated for several reasons. Although the Bloch wave method is powerful for the understanding of physical insights of electron diffraction, particularly electron transmission diffraction, it is not readily available for the simulation of various surface imperfection in electron reflection diffraction since it is basically a method for bulk materials and perfect surface. When the multislice method due to Cowley & Moodie is used for electron reflection, the “edge effects” stand firmly in the way of reaching a stationary solution for HEER. The multislice method due to Maksym & Beeby is valid only for an 2-D periodic surface.Now, a method for solving stationary solution of HEER for an arbitrary surface is available, which is called the Edge Patching method in Multislice-Only mode (the EPMO method). The analytical basis for this method can be attributed to two important characters of HEER: 1) 2-D dependence of the wave fields and 2) the Picard iteractionlike character of multislice calculation due to Cowley and Moodie in the Bragg case.

Direct imaging of charge transfer

1996 ◽  
Vol 54 ◽  
pp. 680-681
Author(s):  
Yimei Zhu ◽  
J. Tafto
Keyword(s):  
Charge Transfer ◽  
Electron Diffraction ◽  
Scattering Amplitude ◽  
High Temperature Superconductors ◽  
Charge Carriers ◽  
Image Charge ◽  
Net Charge ◽  
Long Time ◽  
Electron Holes ◽  
First Time

The electron holes confined to the CuO2-plane are the charge carriers in high-temperature superconductors, and thus, the distribution of charge plays a key role in determining their superconducting properties. While it has been known for a long time that in principle, electron diffraction at low angles is very sensitive to charge transfer, we, for the first time, show that under a proper TEM imaging condition, it is possible to directly image charge in crystals with a large unit cell. We apply this new way of studying charge distribution to the technologically important Bi2Sr2Ca1Cu2O8+δ superconductors.Charged particles interact with the electrostatic potential, and thus, for small scattering angles, the incident particle sees a nuclei that is screened by the electron cloud. Hence, the scattering amplitude mainly is determined by the net charge of the ion. Comparing with the high Z neutral Bi atom, we note that the scattering amplitude of the hole or an electron is larger at small scattering angles. This is in stark contrast to the displacements which contribute negligibly to the electron diffraction pattern at small angles because of the short g-vectors.

Microstructural characterization of plasma-processed Ti-Al metal matrix composites

1989 ◽  
Vol 47 ◽  
pp. 552-553
Author(s):  
M. G. Burke ◽  
M. N. Gungor ◽  
M. A. Burke
Keyword(s):  
High Temperature ◽  
Titanium Aluminide ◽  
Plasma Processing ◽  
Microstructural Characterization ◽  
High Temperature Strength ◽  
Matrix Composites ◽  
Intermetallic Matrix ◽  
Long Time ◽  
Strength And Stiffness ◽  
Intermetallic Matrix Composites

Intermetallic matrix composites are candidates for ultrahigh temperature service when light weight and high temperature strength and stiffness are required. Recent efforts to produce intermetallic matrix composites have focused on the titanium aluminide (TiAl) system with various ceramic reinforcements. In order to optimize the composition and processing of these composites it is necessary to evaluate the range of structures that can be produced in these materials and to identify the characteristics of the optimum structures. Normally, TiAl materials are difficult to process and, thus, examination of a suitable range of structures would not be feasible. However, plasma processing offers a novel method for producing composites from difficult to process component materials. By melting one or more of the component materials in a plasma and controlling deposition onto a cooled substrate, a range of structures can be produced and the method is highly suited to examining experimental composite systems. Moreover, because plasma processing involves rapid melting and very rapid cooling can be induced in the deposited composite, it is expected that processing method can avoid some of the problems, such as interfacial degradation, that are associated with the relatively long time, high temperature exposures that are induced by conventional processing methods.

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