Rates and time scales of clay-mineral formation by weathering in saprolitic regoliths of the southern Appalachians from geochemical mass balance

Treesearch

Jason R. Price; Michael A. Velbel; Lina C. Patino

2005-01-01

Rates of clay formation in three watersheds located at the Coweeta Hydrologic Laboratory, western North Carolina, have been determined from solute flux-based mass balance methods. A system of mass balance equations with enough equations and unknowns to allow calculation of secondary mineral formation rates as well as the more commonly determined primary-...

Simulating ice thickness and velocity evolution of Upernavik Isstrøm 1849-2012 by forcing prescribed terminus positions in ISSM

NASA Astrophysics Data System (ADS)

Haubner, Konstanze; Box, Jason E.; Schlegel, Nicole J.; Larour, Eric Y.; Morlighem, Mathieu; Solgaard, Anne M.; Kjeldsen, Kristian K.; Larsen, Signe H.; Rignot, Eric; Dupont, Todd K.; Kjær, Kurt H.

2018-04-01

Tidewater glacier velocity and mass balance are known to be highly responsive to terminus position change. Yet it remains challenging for ice flow models to reproduce observed ice margin changes. Here, using the Ice Sheet System Model (ISSM; Larour et al. 2012), we simulate the ice velocity and thickness changes of Upernavik Isstrøm (north-western Greenland) by prescribing a collection of 27 observed terminus positions spanning 164 years (1849-2012). The simulation shows increased ice velocity during the 1930s, the late 1970s and between 1995 and 2012 when terminus retreat was observed along with negative surface mass balance anomalies. Three distinct mass balance states are evident in the reconstruction: (1849-1932) with near zero mass balance, (1932-1992) with ice mass loss dominated by ice dynamical flow, and (1998-2012), when increased retreat and negative surface mass balance anomalies led to mass loss that was twice that of any earlier period. Over the multi-decadal simulation, mass loss was dominated by thinning and acceleration responsible for 70 % of the total mass loss induced by prescribed change in terminus position. The remaining 30 % of the total ice mass loss resulted directly from prescribed terminus retreat and decreasing surface mass balance. Although the method can not explain the cause of glacier retreat, it enables the reconstruction of ice flow and geometry during 1849-2012. Given annual or seasonal observed terminus front positions, this method could be a useful tool for evaluating simulations investigating the effect of calving laws.

Insight into glacier climate interaction: reconstruction of the mass balance field using ice extent data

NASA Astrophysics Data System (ADS)

Visnjevic, Vjeran; Herman, Frédéric; Licul, Aleksandar

2016-04-01

With the end of the Last Glacial Maximum (LGM), about 20 000 years ago, ended the most recent long-lasting cold phase in Earth's history. We recently developed a model that describes large-scale erosion and its response to climate and dynamical changes with the application to the Alps for the LGM period. Here we will present an inverse approach we have recently developed to infer the LGM mass balance from known ice extent data, focusing on a glacier or ice cap. The ice flow model is developed using the shallow ice approximation and the developed codes are accelerated using GPUs capabilities. The mass balance field is the constrained variable defined by the balance rate β and the equilibrium line altitude (ELA), where c is the cutoff value: b = max(βṡ(S(z) - ELA), c) We show that such a mass balance can be constrained from the observed past ice extent and ice thickness. We are also investigating several different geostatistical methods to constrain spatially variable mass balance, and derive uncertainties on each of the mass balance parameters.

Using chloride and chlorine-36 as soil-water tracers to estimate deep percolation at selected locations on the U.S. Department of Energy Hanford Site, Washington

USGS Publications Warehouse

Prych, Edmund A.

1998-01-01

A chloride mass-balance method and a chlorine-36 isotope bomb-pulse method were used to estimate long-term average rates of deep percolation at at the U.S. Department of Energy Hanford Site. Because the bomb-pulse method typically gives an upper limit and the mass-balance method may underestimate, estimates from both methods probably bracket actual rates.

Mass-balance modelling of Ak-Shyirak massif Glaciers, Inner Tian Shan

NASA Astrophysics Data System (ADS)

Rets, Ekaterina; Barandun, Martina; Belozerov, Egor; Petrakov, Dmitry; Shpuntova, Alena

2017-04-01

Tian Shan is a water tower of Central Asia. Rapid and accelerating glacier downwasting is typical for this region. Study sites - Sary-Tor glacier and Glacier No.354 are located in Ak-Shyirak massif, Naryn headwaters. Sary-Tor was chosen as representative for Ak-Shyirak (Ushnurtsev, 1991; Oledeneniye TianShanya, 1995) for direct mass-balance measurements in 1985-1991. Glacier No.354 was an object of direct mass-balance measurements for 2011-2016. An energy-balance distributed A-Melt model (Rets et al, 2010) was used to reconstruct mass-balance for the glaciers for 2003-2015. Verification of modelingresults showed a good reproduction of direct melting measurements data on ablation stakes and mass loss according to geodetic method. Modeling results for Glacier No. 354 were compared to different modeling approach: distributed accumulation and temperature-index melt (Kronenberg et al, 2016)

Evapotranspiration Measurement and Estimation: Weighing Lysimeter and Neutron Probe Based Methods Compared with Eddy Covariance

NASA Astrophysics Data System (ADS)

Evett, S. R.; Gowda, P. H.; Marek, G. W.; Alfieri, J. G.; Kustas, W. P.; Brauer, D. K.

2014-12-01

Evapotranspiration (ET) may be measured by mass balance methods and estimated by flux sensing methods. The mass balance methods are typically restricted in terms of the area that can be represented (e.g., surface area of weighing lysimeter (LYS) or equivalent representative area of neutron probe (NP) and soil core sampling techniques), and can be biased with respect to ET from the surrounding area. The area represented by flux sensing methods such as eddy covariance (EC) is typically estimated with a flux footprint/source area model. The dimension, position of, and relative contribution of upwind areas within the source area are mainly influenced by sensor height, wind speed, atmospheric stability and wind direction. Footprints for EC sensors positioned several meters above the canopy are often larger than can be economically covered by mass balance methods. Moreover, footprints move with atmospheric conditions and wind direction to cover different field areas over time while mass balance methods are static in space. Thus, EC systems typically sample a much greater field area over time compared with mass balance methods. Spatial variability of surface cover can thus complicate interpretation of flux estimates from EC systems. The most commonly used flux estimation method is EC; and EC estimates of latent heat energy (representing ET) and sensible heat fluxes combined are typically smaller than the available energy from net radiation and soil heat flux (commonly referred to as lack of energy balance closure). Reasons for this are the subject of ongoing research. We compare ET from LYS, NP and EC methods applied to field crops for three years at Bushland, Texas (35° 11' N, 102° 06' W, 1170 m elevation above MSL) to illustrate the potential problems with and comparative advantages of all three methods. In particular, we examine how networks of neutron probe access tubes can be representative of field areas large enough to be equivalent in size to EC footprints, and how the ET data from these methods can address bias and accuracy issues.

Ultrasonic detection of solid phase mass flow ratio of pneumatic conveying fly ash

NASA Astrophysics Data System (ADS)

Duan, Guang Bin; Pan, Hong Li; Wang, Yong; Liu, Zong Ming

2014-04-01

In this paper, ultrasonic attenuation detection and weight balance are adopted to evaluate the solid mass ratio in this paper. Fly ash is transported on the up extraction fluidization pneumatic conveying workbench. In the ultrasonic test. McClements model and Bouguer-Lambert-Beer law model were applied to formulate the ultrasonic attenuation properties of gas-solid flow, which can give the solid mass ratio. While in the method of weigh balance, the averaged mass addition per second can reveal the solids mass flow ratio. By contrast these two solid phase mass ratio detection methods, we can know, the relative error is less.

A mass balance approach for calculation of recovery and binding enables the use of ultrafiltration as a rapid method for measurement of plasma protein binding for even highly lipophilic compounds.

PubMed

Wang, Changguang; Williams, Noelle S

2013-03-05

The aim of this study is to further validate the use of ultrafiltration (UF) as a method for determining plasma protein binding (PPB) by demonstrating that non-specific binding (NSB) is not a limitation, even for highly lipophilic compounds, because NSB sites on the apparatus are passivated in the presence of plasma. Mass balance theory was used to calculate recovery of 20 commercial and seven investigational compounds during ultrafiltration in the presence and absence of plasma. PPB was also measured using this mass balance approach for comparison to PPB determined by rapid equilibrium dialysis (RED) and as found in the literature. Compound recovery during UF was dramatically different in the presence and absence of plasma for compounds with high NSB in PBS only. A comparison of PPB calculated by ultrafiltration with literature values or calculated by RED gave concordant results. Discrepancies could be explained by changes in pH, insufficient time to equilibrium, or compound instability during RED, problems which were circumvented by ultrafiltration. Therefore, NSB, as measured by the traditional incubation of compound in PBS, need not be an issue when choosing UF as a PPB assay method. It is more appropriate to calculate compound recovery from the device in plasma as measured by mass balance to determine the suitability of the method for an individual compound. The speed with which UF can be conducted additionally avoids changes in pH or compound loss that can occur with other methods. The mass balance approach to UF is thus a preferred method for rapid determination of PPB. Copyright © 2012 Elsevier B.V. All rights reserved.

The Temporal Dynamics of Terrestrial Organic Matter Transfer to the Oceans: Initial Assessment and Application

DTIC Science & Technology

2007-06-01

2.2.4 A QUALITATIVE VIEW OF OC CYCLING 44 2.2.5 COUPLED ISOTOPE MASS BALANCE CALCULATIONS 47 2.3 CONCLUSIONS 56 ACKNOWLEDGEMENTS 57 REFERENCES 58...METHODS 71 3.2 RESULTS & DISCUSSION 73 3.2.1 CHRONOLOGY DEVELOPMENT 73 3.2.2 ELEMENTAL AND ISOTOPIC PROFILES 77 3.2.3 MASS BALANCE CALCULATIONS 80 3.3...2005). Within this framework, isotopic mass balance calculations used to assess the fractional abundance of modem and ancient OC (Blair et al., 2003

On-field study of anaerobic digestion full-scale plants (part I): an on-field methodology to determine mass, carbon and nutrients balance.

PubMed

Schievano, Andrea; D'Imporzano, Giuliana; Salati, Silvia; Adani, Fabrizio

2011-09-01

The mass balance (input/output mass flows) of full-scale anaerobic digestion (AD) processes should be known for a series of purposes, e.g. to understand carbon and nutrients balances, to evaluate the contribution of AD processes to elemental cycles, especially when digestates are applied to agricultural land and to measure the biodegradation yields and the process efficiency. In this paper, three alternative methods were studied, to determine the mass balance in full-scale processes, discussing their reliability and applicability. Through a 1-year survey on three full-scale AD plants and through 38 laboratory-scale batch digesters, the congruency of the considered methods was demonstrated and a linear equation was provided that allows calculating the wet weight losses (WL) from the methane produced (MP) by the plant (WL=41.949*MP+20.853, R(2)=0.950, p<0.01). Additionally, this new tool was used to calculate carbon, nitrogen, phosphorous and potassium balances of the three observed AD plants. Copyright © 2011 Elsevier Ltd. All rights reserved.

A new approach to enforce element-wise mass/species balance using the augmented Lagrangian method

NASA Astrophysics Data System (ADS)

Chang, J.; Nakshatrala, K.

2015-12-01

The least-squares finite element method (LSFEM) is one of many ways in which one can discretize and express a set of first ordered partial differential equations as a mixed formulation. However, the standard LSFEM is not locally conservative by design. The absence of this physical property can have serious implications in the numerical simulation of subsurface flow and transport. Two commonly employed ways to circumvent this issue is through the Lagrange multiplier method, which explicitly satisfies the element-wise divergence by introducing new unknowns, or through appending a penalty factor to the continuity constraint, which reduces the violation in the mass balance. However, these methodologies have some well-known drawbacks. Herein, we propose a new approach to improve the local balance of species/mass balance. The approach augments constraints to a least-square function by a novel mathematical construction of the local species/mass balance, which is different from the conventional ways. The resulting constrained optimization problem is solved using the augmented Lagrangian, which corrects the balance errors in an iterative fashion. The advantages of this methodology are that the problem size is not increased (thus preserving the symmetry and positive definite-ness) and that one need not provide an accurate guess for the initial penalty to reach a prescribed mass balance tolerance. We derive the least-squares weighting needed to ensure accurate solutions. We also demonstrate the robustness of the weighted LSFEM coupled with the augmented Lagrangian by solving large-scale heterogenous and variably saturated flow through porous media problems. The performance of the iterative solvers with respect to various user-defined augmented Lagrangian parameters will be documented.

Rates of biotite weathering, and clay mineral transformation and neoformation, determined from watershed geochemical mass-balance methods for the Coweeta Hydrologic Laboratory, Southern Blue Ridge Mountains, North Carolina, USA

Treesearch

Jason R. Price; Michael A. Velbel

2013-01-01

Biotite is a common constituent of silicate bedrock. Its weathering releases plant nutrients and consumes atmospheric CO2. Because of its stoichiometric relationship with its transformational weathering product and sensitivity to botanical activity, calculating biotite weathering rates using watershed mass-balance methods has proven challenging....

CHEMICAL MASS BALANCE MODEL: EPA-CMB8.2

EPA Science Inventory

The Chemical Mass Balance (CMB) method has been a popular approach for receptor modeling of ambient air pollutants for over two decades. For the past few years the U.S. Environmental Protection Agency's Office of Research and Development (ORD) and Office of Air Quality Plannin...

Mass Balance Modelling of Saskatchewan Glacier, Canada Using Empirically Downscaled Reanalysis Data

NASA Astrophysics Data System (ADS)

Larouche, O.; Kinnard, C.; Demuth, M. N.

2017-12-01

Observations show that glaciers around the world are retreating. As sites with long-term mass balance observations are scarce, models are needed to reconstruct glacier mass balance and assess its sensitivity to climate. In regions with discontinuous and/or sparse meteorological data, high-resolution climate reanalysis data provide a convenient alternative to in situ weather observations, but can also suffer from strong bias due to the spatial and temporal scale mismatch. In this study we used data from the North American Regional Reanalysis (NARR) project with a 30 x 30 km spatial resolution and 3-hour temporal resolution to produce the meteorological forcings needed to drive a physically-based, distributed glacier mass balance model (DEBAM, Hock and Holmgren 2005) for the historical period 1979-2016. A two-year record from an automatic weather station (AWS) operated on Saskatchewan Glacier (2014-2016) was used to downscale air temperature, relative humidity, wind speed and incoming solar radiation from the nearest NARR gridpoint to the glacier AWS site. An homogenized historical precipitation record was produced using data from two nearby, low-elevation weather stations and used to downscale the NARR precipitation data. Three bias correction methods were applied (scaling, delta and empirical quantile mapping - EQM) and evaluated using split sample cross-validation. The EQM method gave better results for precipitation and for air temperature. Only a slight improvement in the relative humidity was obtained using the scaling method, while none of the methods improved the wind speed. The later correlates poorly with AWS observations, probably because the local glacier wind is decoupled from the larger scale NARR wind field. The downscaled data was used to drive the DEBAM model in order to reconstruct the mass balance of Saskatchewan Glacier over the past 30 years. The model was validated using recent snow thickness measurements and previously published geodetic mass balance estimates.

REVIEW OF VOLATILE ORGANIC COMPOUND SOURCE APPORTIONMENT BY CHEMICAL MASS BALANCE. (R826237)

EPA Science Inventory

The chemical mass balance (CMB) receptor model has apportioned volatile organic compounds (VOCs) in more than 20 urban areas, mostly in the United States. These applications differ in terms of the total fraction apportioned, the calculation method, the chemical compounds used ...

Method of Manufacturing a Micromechanical Oscillating Mass Balance

NASA Technical Reports Server (NTRS)

Altemir, David A. (Inventor)

1999-01-01

A micromechanical oscillating mass balance and method adapted for measuring minute quantities of material deposited at a selected location, such as during a vapor deposition process. The invention comprises a vibratory composite beam which includes a dielectric layer sandwiched between two conductive layers.The beam is positioned in a magnetic field. An alternating current passes through one conductive layers, the beam oscillates, inducing an output current in the second conductive layer, which is analyzed to determine the resonant frequency of the beam. As material is deposited on the beam, the mass of the beam increases and the resonant frequency of the beam shifts, and the mass added is determined.

Comparison of Glaciological and Gravimetric Glacier Mass Balance Measurements of Taku and Lemon Creek Glaciers, Southeast Alaska

NASA Astrophysics Data System (ADS)

Vogler, K.; McNeil, C.; Bond, M.; Getraer, B.; Huxley-Reicher, B.; McNamara, G.; Reinhardt-Ertman, T.; Silverwood, J.; Kienholz, C.; Beedle, M. J.

2017-12-01

Glacier-wide annual mass balances (Ba) have been calculated for Taku (726 km2) and Lemon Creek glaciers (10.2 km2) since 1946 and 1953 respectively. These are the longest mass balance records in North America, and the only Ba time-series available for Southeast Alaska, making them particularly valuable for the global glacier mass balance monitoring network. We compared Ba time-series from Taku and Lemon Creek glaciers to Gravity Recovery and Climate Experiment (GRACE) mascon solutions (1352 and 1353) during the 2004-2015 period to assess how well these gravimetric solutions reflect individual glaciological records. Lemon Creek Glacier is a challenging candidate for this comparison because it is small compared to the 12,100 km2 GRACE mascon solutions. Taku Glacier is equally challenging because its mass balance is stable compared to the negative balances dominating its neighboring glaciers. Challenges notwithstanding, a high correlation between the glaciological and gravimetrically-derived Ba for Taku and Lemon Creek glaciers encourage future use of GRACE to measure glacier mass balance. Additionally, we employed high frequency ground penetrating radar (GPR) to measure the variability of accumulation around glaciological sites to assess uncertainty in our glaciological measurements, and the resulting impact to Ba. Finally, we synthesize this comparison of glaciological and gravimetric mass balance solutions with a discussion of potential sources of error in both methods and their combined utility for measuring regional glacier change during the 21st century.

Geodetic Mass Balance of the Northern Patagonian Icefield from 2000 to 2012 using two independent methods

NASA Astrophysics Data System (ADS)

Dussaillant, Inés; Berthier, Etienne; Brun, Fanny

2018-02-01

We compare two independent estimates of the rate of elevation change and geodetic mass balance of the Northern Patagonian Icefield (NPI) between 2000 (3856 km²) and 2012 (3740 km²) from space-borne data. The first is obtained by differencing the Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) from February 2000 and a Satellite pour l’Observation de la Terre 5 (SPOT5) DEM from March 2012. The second is deduced by fitting pixel-based linear elevation trends over 118 DEMs calculated from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) stereo images acquired between 2000 and 2012. Both methods lead to similar and strongly negative icefield-wide mass balances of -1.02±0.21 and -1.06±0.14 m w.e. yr-1 respectively, which is in agreement with earlier studies. Contrasting glacier responses are observed, with individual glacier mass balances ranging from -0.15 to -2.30 m w.e. yr-1 (standard deviation = 0.49 m w.e. yr-1; N = 38). For individual glaciers, the two methods agree within error bars, except for small glaciers poorly sampled in the SPOT5 DEM due to clouds. Importantly, our study confirms the lack of penetration of the C-band SRTM radar signal into the NPI snow and firn except for a region above 2900 m a.s.l. covering less than 1% of the total area. Ignoring penetration would bias the mass balance by only 0.005 m w.e. yr-1. A strong advantage of the ASTER method is that it relies only on freely available data and can thus be extended to other glacierized areas.

Survey and Experimental Testing of Nongravimetric Mass Measurement Devices

NASA Technical Reports Server (NTRS)

Oakey, W. E.; Lorenz, R.

1977-01-01

Documentation presented describes the design, testing, and evaluation of an accelerated gravimetric balance, a low mass air bearing oscillator of the spring-mass type, and a centrifugal device for liquid mass measurement. A direct mass readout method was developed to replace the oscillation period readout method which required manual calculations to determine mass. A protoype 25 gram capacity micro mass measurement device was developed and tested.

Field Balancing of Magnetically Levitated Rotors without Trial Weights

PubMed Central

Fang, Jiancheng; Wang, Yingguang; Han, Bangcheng; Zheng, Shiqiang

2013-01-01

Unbalance in magnetically levitated rotor (MLR) can cause undesirable synchronous vibrations and lead to the saturation of the magnetic actuator. Dynamic balancing is an important way to solve these problems. However, the traditional balancing methods, using rotor displacement to estimate a rotor's unbalance, requiring several trial-runs, are neither precise nor efficient. This paper presents a new balancing method for an MLR without trial weights. In this method, the rotor is forced to rotate around its geometric axis. The coil currents of magnetic bearing, rather than rotor displacement, are employed to calculate the correction masses. This method provides two benefits when the MLR's rotation axis coincides with the geometric axis: one is that unbalanced centrifugal force/torque equals the synchronous magnetic force/torque, and the other is that the magnetic force is proportional to the control current. These make calculation of the correction masses by measuring coil current with only a single start-up precise. An unbalance compensation control (UCC) method, using a general band-pass filter (GPF) to make the MLR spin around its geometric axis is also discussed. Experimental results show that the novel balancing method can remove more than 92.7% of the rotor unbalance and a balancing accuracy of 0.024 g mm kg−1 is achieved.

Nitrate Removal in Two Relict Oxbow Urban Wetlands: A 15N Mass-balance Approach

EPA Science Inventory

A 15N-tracer method was used to quantify nitrogen (N) removal processes in two relict oxbow wetlands located adjacent to the Minebank Run restored stream reach in Baltimore County (Maryland, USA) during summer 2009 and early spring 2010. A mass-balance approach was used to determ...

A New Proposal to Redefine Kilogram by Measuring the Planck Constant Based on Inertial Mass

NASA Astrophysics Data System (ADS)

Liu, Yongmeng; Wang, Dawei

2018-04-01

A novel method to measure the Planck constant based on inertial mass is proposed here, which is distinguished from the conventional Kibble balance experiment which is based on the gravitational mass. The kilogram unit is linked to the Planck constant by calculating the difference of the parameters, i.e. resistance, voltage, velocity and time, which is measured in a two-mode experiment, unloaded mass mode and the loaded mass mode. In principle, all parameters measured in this experiment can reach a high accuracy, as that in Kibble balance experiment. This method has an advantage that some systematic error can be eliminated in difference calculation of measurements. In addition, this method is insensitive to air buoyancy and the alignment work in this experiment is easy. At last, the initial design of the apparatus is presented.

Dynamical adjustment of Scandinavian glacier mass-balance time series

NASA Astrophysics Data System (ADS)

Bonan, D.; Christian, J. E.; Christianson, K. A.

2017-12-01

Glacier mass wastage is often cited as one of the most visible manifestations of anthropogenic climate change. Annual glacier mass-balance is related to local climate and atmospheric circulation, as it is defined as the yearly sum of accumulation and ablation—processes that are strongly influenced by year-to-year fluctuations in precipitation and temperature. Glacier response to a climatic trend can, however, be masked by internal variability in atmospheric circulation, and by non-climatic factors (such as topographic control, wind deposition, and incident solar radiation). Thus, unambiguous attribution of a negative glacier mass-balance trend to anthropogenic forcing remains challenging. Maritime glacier mass-balance records may be especially difficult to interpret due to the high winter balances from decadal-scale climate oscillations and the relatively short time series. Here we examine the influence of climate and atmospheric circulation variability on 14 Norwegian glaciers that span 20° of latitude, from southern Norway to Svalbard. We use dynamical adjustment—a statistical method based on partial least squares regression—to identify the components of variability within the mass-balance records that are associated with the time-varying sea level pressure (SLP) and sea surface temperature (SST) fields. We find that 30-50% of the variance in the winter mass-balance records of the glaciers in southern Norway is explained by using sea level pressure as a predictor. The leading SLP predictor pattern mimics the spatial signature of the North Atlantic Oscillation (NAO), indicating that winter balance is strongly influenced by the NAO. Moreover, the adjusted mass-balance records indicate a geographic trend: the southern Norwegian glaciers have significant negative trends in the summer balance that remain negative after adjustment, while the more northern glaciers have negative winter balance trends that only become significant after adjustment. We look into anthropogenic warming to explain the trends after dynamical adjustment.

Research on dynamic balancing simulation of rotary shaft based on ADAMS

NASA Astrophysics Data System (ADS)

Zheng, Weiqiang; Rui, Chengjie; Yang, Jie; Liu, Pingyi

2018-02-01

Due to the design and processing technology of rotary shaft, the mass center of it does not coincide with the rotating axis of the rotary shaft and there is an unbalanced mass. The unbalanced mass can have some disadvantages, such as the centrifugal force, the vibration and so on. Those disadvantages could reduce the accuracy and service life of the equipment.In this paper, the dynamic balance of the rotary shaft is analysed by the theory analysis combined with the dynamic simulation software. This method ensures that the rotary shaft meets the dynamic balancing requirements during the design stage. It effectively supports the structural design of the rotary shift, and provides a way of thinking and method for the design and development of the same type of products.

Monitoring southwest Greenland's ice sheet melt with ambient seismic noise.

PubMed

Mordret, Aurélien; Mikesell, T Dylan; Harig, Christopher; Lipovsky, Bradley P; Prieto, Germán A

2016-05-01

The Greenland ice sheet presently accounts for ~70% of global ice sheet mass loss. Because this mass loss is associated with sea-level rise at a rate of 0.7 mm/year, the development of improved monitoring techniques to observe ongoing changes in ice sheet mass balance is of paramount concern. Spaceborne mass balance techniques are commonly used; however, they are inadequate for many purposes because of their low spatial and/or temporal resolution. We demonstrate that small variations in seismic wave speed in Earth's crust, as measured with the correlation of seismic noise, may be used to infer seasonal ice sheet mass balance. Seasonal loading and unloading of glacial mass induces strain in the crust, and these strains then result in seismic velocity changes due to poroelastic processes. Our method provides a new and independent way of monitoring (in near real time) ice sheet mass balance, yielding new constraints on ice sheet evolution and its contribution to global sea-level changes. An increased number of seismic stations in the vicinity of ice sheets will enhance our ability to create detailed space-time records of ice mass variations.

Multi-decadal mass balance series of three Kyrgyz glaciers inferred from modelling constrained with repeated snow line observations

NASA Astrophysics Data System (ADS)

Barandun, Martina; Huss, Matthias; Usubaliev, Ryskul; Azisov, Erlan; Berthier, Etienne; Kääb, Andreas; Bolch, Tobias; Hoelzle, Martin

2018-06-01

Glacier surface mass balance observations in the Tien Shan and Pamir are relatively sparse and often discontinuous. Nevertheless, glaciers are one of the most important components of the high-mountain cryosphere in the region as they strongly influence water availability in the arid, continental and intensely populated downstream areas. This study provides reliable and continuous surface mass balance series for selected glaciers located in the Tien Shan and Pamir-Alay. By cross-validating the results of three independent methods, we reconstructed the mass balance of the three benchmark glaciers, Abramov, Golubin and Glacier no. 354 for the past 2 decades. By applying different approaches, it was possible to compensate for the limitations and shortcomings of each individual method. This study proposes the use of transient snow line observations throughout the melt season obtained from satellite optical imagery and terrestrial automatic cameras. By combining modelling with remotely acquired information on summer snow depletion, it was possible to infer glacier mass changes for unmeasured years. The model is initialized with daily temperature and precipitation data collected at automatic weather stations in the vicinity of the glacier or with adjusted data from climate reanalysis products. Multi-annual mass changes based on high-resolution digital elevation models and in situ glaciological surveys were used to validate the results for the investigated glaciers. Substantial surface mass loss was confirmed for the three studied glaciers by all three methods, ranging from -0.30 ± 0.19 to -0.41 ± 0.33 m w.e. yr-1 over the 2004-2016 period. Our results indicate that integration of snow line observations into mass balance modelling significantly narrows the uncertainty ranges of the estimates. Hence, this highlights the potential of the methodology for application to unmonitored glaciers at larger scales for which no direct measurements are available.

Annual and seasonal mass balances of Chhota Shigri Glacier (benchmark glacier, Western Himalaya), India

NASA Astrophysics Data System (ADS)

Mandal, Arindan; Ramanathan, Alagappan; Farooq Azam, Mohd; Wagnon, Patrick; Vincent, Christian; Linda, Anurag; Sharma, Parmanand; Angchuk, Thupstan; Bahadur Singh, Virendra; Pottakkal, Jose George; Kumar, Naveen; Soheb, Mohd

2015-04-01

Several studies on Himalayan glaciers have been recently initiated as they are of particular interest in terms of future water supply, regional climate change and sea-level rise. In 2002, a long-term monitoring program was initiated on Chhota Shigri Glacier (15.7 square km, 9 km long, 6263-4050 m a.s.l.) located in Lahaul and Spiti Valley, Himachal Pradesh, India. This glacier lies in the monsoon-arid transition zone (western Himalaya) and is a representative glacier in Lahaul and Spiti Valley. While annual mass balances have been measured continuously since 2002 using the glaciological method, seasonal scale observations began in 2009. The annual and seasonal mass balances were then analyzed along with meteorological conditions in order to understand the role of winter and summer balances on annual glacier-wide mass balance of Chhota Shigri glacier. During the period 2002-2013, the glacier experienced a negative glacier-wide mass balance of -0.59±0.40 m w.e. a-1 with a cumulative glaciological mass balance of -6.45 m w.e. Annual glacier-wide mass balances were negative except for four years (2004/05, 2008/09, 2009/10 and 2010/11) where it was generally close to balanced conditions. Equilibrium line altitude (ELA) for steady state condition is calculated as 4950 m a.s.l. corresponding to an accumulation area ratio (AAR) of 62% using annual glacier-wide mass balance, ELA and AAR data between 2002 and 2013. The winter glacier-wide mass balance between 2009 and 2013 ranges from a maximum value of 1.38 m w.e. in 2009/10 to a minimum value of 0.89 in 2012/13 year whereas the summer glacier-wide mass balance varies from the highest value of -0.95 m w.e. in 2010/11 to the lowest value of -1.72 m w.e. in 2011/12 year. The mean vertical mass balance gradient between 2002 and 2013 was 0.66 m w.e. (100 m)-1 quite similar to Alps, Nepalese Himalayas etc. Over debris covered area, the gradients are highly variable with a negative mean value of -2.15 m w.e. (100 m)-1 over 2002-2013 observation period. The negative gradients can be explained by the thickness of debris cover that increases with decrease in altitude, thus protecting the glacier more efficiently at lower altitudes. Mass balance is strongly dependent on debris cover, exposure (solar radiation) and the shading effect of surrounding steep slopes.

Monitoring the variations of the oxygen transfer rate in a full scale membrane bioreactor using daily mass balances.

PubMed

Racault, Y; Stricker, A-E; Husson, A; Gillot, S

2011-01-01

Oxygen transfer in biological wastewater treatment processes with high sludge concentration, such as membrane bioreactor (MBR), is an important issue. The variation of alpha-factor versus mixed liquor suspended solids (MLSS) concentration was investigated in a full scale MBR plant under process conditions, using mass balances. Exhaustive data from the Supervisory Control And Data Acquisition (SCADA) and from additional online sensors (COD, DO, MLSS) were used to calculate the daily oxygen consumption (OC) using a non-steady state mass balance for COD and total N on a 24-h basis. To close the oxygen balance, OC has to match the total oxygen transfer rate (OTRtot) of the system, which is provided by fine bubble (FB) diffusers in the aeration tank and coarse bubbles (CB) in separate membrane tanks. First assessing OTR(CB) then closing the balance OC = OTRtot allowed to calculate OTR(FB) and to fit an exponential relationship between OTR(FB) and MLSS. A comparison of the alpha-factor obtained by this balance method and by direct measurements with the off-gas method on the same plant is presented and discussed.

Improving Estimates of Greenland Ice Sheet Surface Mass Balance with Satellite Observations

NASA Astrophysics Data System (ADS)

Briggs, K.

2016-12-01

Mass losses from the Greenland Ice Sheet have been accelerating over recent years (e.g. McMillan et al., 2016; Velicogna et al., 2014). This acceleration has predominantly been linked to increasing rates of negative surface mass balance, and in particular, increasing ice surface melt rates (e.g. McMillan et al., 2016; Velicogna et al., 2014). At the ice sheet scale, SMB is assessed using SMB model outputs, which in addition to enabling understanding of the origin of mass balance signals, are required as ancillary data in mass balance assessments from altimetry and the mass budget method. Due to the importance of SMB for mass balance over Greenland and the sensitivity of mass balance assessments to SMB model outputs, high accuracy of these models is crucial. A critical limiting factor in SMB modeling is however, a lack of in-situ data that is required for model constraint and evaluation. Such data is limited in time and space due to inherent logistical and financial constraints. Remote sensing datasets, being spatially extensive and relatively densely sampled in both space and time, do not suffer such constraints. Here, we show satellite observations of Greenland SMB. McMillan, M., Leeson, A., Shepherd, A., Briggs, K., Armitage, T. W.K., Hogg, A., Kuipers Munneke, P., van den Broeke, M., Noël, B., van de Berg, W., Ligtenberg, S., Horwath, M., Groh, A. , Muir, A. and Gilbert, L. 2016. A high resolution record of Greenland Mass Balance. Geophysical Research Letters. 43, doi:10.1002/2016GL069666 Velicogna, I., Sutterley, T. C. and van den Broeke, M. R. 2014. Regional acceleration in ice mass loss from Greenland and Antarctica using GRACE time-variable gravity data. Geophysical Research Letters. 41, 8130-8137, doi:10.1002/2014GL061052

The unbalanced signal measuring of automotive brake drum

NASA Astrophysics Data System (ADS)

Wang, Xiao-Dong; Ye, Sheng-Hua; Zhang, Bang-Cheng

2005-04-01

For the purpose of the research and development of automatic balancing system by mass removing, the dissertation deals with the measuring method of the unbalance signal, the design the automatic balance equipment and the software. This paper emphases the testing system of the balancer of automotive brake drum. The paper designs the band-pass filter product with favorable automatic follow of electronic product, and with favorable automatic follow capability, filtration effect and stability. The system of automatic balancing system by mass removing based on virtual instrument is designed in this paper. A lab system has been constructed. The results of contrast experiments indicate the notable effect of 1-plane automatic balance and the high precision of dynamic balance, and demonstrate the application value of the system.

The influence of topographic feedback on a coupled mass balance and ice-flow model for Vestfonna ice-cap, Svalbard

NASA Astrophysics Data System (ADS)

Schäfer, Martina; Möller, Marco; Zwinger, Thomas; Moore, John

2016-04-01

Using a coupled simulation set-up between a by statistical climate data forced and to ice-cap resolution downscaled mass balance model and an ice-dynamic model, we study coupling effects for the Vestfonna ice cap, Nordaustlandet, Svalbard, by analysing the impacts of different imposed coupling intervals on mass-balance and sea-level rise (SLR) projections. Based on a method to estimate errors introduced by different coupling schemes, we find that neglecting the topographic feedback in the coupling leads to underestimations of 10-20% in SLR projections on century time-scales in our model compared to full coupling (i.e., exchange of properties using smallest occurring time-step). Using the same method it also is shown that parametrising mass-balance adjustment for changes in topography using lapse rates is a - in computational terms - cost-effective reasonably accurate alternative applied to an ice-cap like Vestfonna. We test the forcing imposed by different emission pathways (RCP 2.4, 4.5, 6.0 and 8.5). For most of them, over the time-period explored (2000-2100), fast-flowing outlet glaciers decrease in impacting SLR due to their deceleration and reduced mass flux as they thin and retreat from the coast, hence detaching from the ocean and thereby losing their major mass drainage mechanism, i.e., calving.

Application of quantitative 1H NMR for the calibration of protoberberine alkaloid reference standards.

PubMed

Wu, Yan; He, Yi; He, Wenyi; Zhang, Yumei; Lu, Jing; Dai, Zhong; Ma, Shuangcheng; Lin, Ruichao

2014-03-01

Quantitative nuclear magnetic resonance spectroscopy (qNMR) has been developed into an important tool in the drug analysis, biomacromolecule detection, and metabolism study. Compared with mass balance method, qNMR method bears some advantages in the calibration of reference standard (RS): it determines the absolute amount of a sample; other chemical compound and its certified reference material (CRM) can be used as internal standard (IS) to obtain the purity of the sample. Protoberberine alkaloids have many biological activities and have been used as reference standards for the control of many herbal drugs. In present study, the qNMR methods were developed for the calibration of berberine hydrochloride, palmatine hydrochloride, tetrahydropalmatine, and phellodendrine hydrochloride with potassium hydrogen phthalate as IS. Method validation was carried out according to the guidelines for the method validation of Chinese Pharmacopoeia. The results of qNMR were compared with those of mass balance method and the differences between the results of two methods were acceptable based on the analysis of estimated measurement uncertainties. Therefore, qNMR is an effective and reliable analysis method for the calibration of RS and can be used as a good complementarity to the mass balance method. Copyright © 2013 Elsevier B.V. All rights reserved.

The effect of adjusting model inputs to achieve mass balance on time-dynamic simulations in a food-web model of Lake Huron

USGS Publications Warehouse

Langseth, Brian J.; Jones, Michael L.; Riley, Stephen C.

2014-01-01

Ecopath with Ecosim (EwE) is a widely used modeling tool in fishery research and management. Ecopath requires a mass-balanced snapshot of a food web at a particular point in time, which Ecosim then uses to simulate changes in biomass over time. Initial inputs to Ecopath, including estimates for biomasses, production to biomass ratios, consumption to biomass ratios, and diets, rarely produce mass balance, and thus ad hoc changes to inputs are required to balance the model. There has been little previous research of whether ad hoc changes to achieve mass balance affect Ecosim simulations. We constructed an EwE model for the offshore community of Lake Huron, and balanced the model using four contrasting but realistic methods. The four balancing methods were based on two contrasting approaches; in the first approach, production of unbalanced groups was increased by increasing either biomass or the production to biomass ratio, while in the second approach, consumption of predators on unbalanced groups was decreased by decreasing either biomass or the consumption to biomass ratio. We compared six simulation scenarios based on three alternative assumptions about the extent to which mortality rates of prey can change in response to changes in predator biomass (i.e., vulnerabilities) under perturbations to either fishing mortality or environmental production. Changes in simulated biomass values over time were used in a principal components analysis to assess the comparative effect of balancing method, vulnerabilities, and perturbation types. Vulnerabilities explained the most variation in biomass, followed by the type of perturbation. Choice of balancing method explained little of the overall variation in biomass. Under scenarios where changes in predator biomass caused large changes in mortality rates of prey (i.e., high vulnerabilities), variation in biomass was greater than when changes in predator biomass caused only small changes in mortality rates of prey (i.e., low vulnerabilities), and was amplified when environmental production was increased. When standardized to mean changes in biomass within each scenario, scenarios when vulnerabilities were low and when fishing mortality was increased explained the most variation in biomass. Our findings suggested that approaches to balancing Ecopath models have relatively little effect on changes in biomass over time, especially when compared to assumptions about how mortality rates of prey change in response to changes in predator biomass. We concluded that when constructing food-web models using EwE, determining the effect of changes in predator biomass on mortality rates of prey should be prioritized over determining the best way to balance the model.

Determination of the Gravitational Constant with a Beam Balance

NASA Astrophysics Data System (ADS)

Schlamminger, St.; Holzschuh, E.; Kündig, W.

2002-09-01

The Newtonian gravitational constant G was determined by means of a novel beam-balance experiment with an accuracy comparable to that of the most precise torsion-balance experiments. The gravitational force of two stainless steel tanks filled with 13 521kg mercury on 1.1kg test masses was measured using a commercial mass comparator. A careful analysis of the data and the experimental error yields G=6.674 07(22)×10-11 m3 kg-1 s-2. This value is in excellent agreement with most values previously obtained with different methods.

A reconciled estimate of ice-sheet mass balance.

PubMed

Shepherd, Andrew; Ivins, Erik R; A, Geruo; Barletta, Valentina R; Bentley, Mike J; Bettadpur, Srinivas; Briggs, Kate H; Bromwich, David H; Forsberg, René; Galin, Natalia; Horwath, Martin; Jacobs, Stan; Joughin, Ian; King, Matt A; Lenaerts, Jan T M; Li, Jilu; Ligtenberg, Stefan R M; Luckman, Adrian; Luthcke, Scott B; McMillan, Malcolm; Meister, Rakia; Milne, Glenn; Mouginot, Jeremie; Muir, Alan; Nicolas, Julien P; Paden, John; Payne, Antony J; Pritchard, Hamish; Rignot, Eric; Rott, Helmut; Sørensen, Louise Sandberg; Scambos, Ted A; Scheuchl, Bernd; Schrama, Ernst J O; Smith, Ben; Sundal, Aud V; van Angelen, Jan H; van de Berg, Willem J; van den Broeke, Michiel R; Vaughan, David G; Velicogna, Isabella; Wahr, John; Whitehouse, Pippa L; Wingham, Duncan J; Yi, Donghui; Young, Duncan; Zwally, H Jay

2012-11-30

We combined an ensemble of satellite altimetry, interferometry, and gravimetry data sets using common geographical regions, time intervals, and models of surface mass balance and glacial isostatic adjustment to estimate the mass balance of Earth's polar ice sheets. We find that there is good agreement between different satellite methods--especially in Greenland and West Antarctica--and that combining satellite data sets leads to greater certainty. Between 1992 and 2011, the ice sheets of Greenland, East Antarctica, West Antarctica, and the Antarctic Peninsula changed in mass by -142 ± 49, +14 ± 43, -65 ± 26, and -20 ± 14 gigatonnes year(-1), respectively. Since 1992, the polar ice sheets have contributed, on average, 0.59 ± 0.20 millimeter year(-1) to the rate of global sea-level rise.

Calibrating a surface mass-balance model for Austfonna ice cap, Svalbard

NASA Astrophysics Data System (ADS)

Schuler, Thomas Vikhamar; Loe, Even; Taurisano, Andrea; Eiken, Trond; Hagen, Jon Ove; Kohler, Jack

2007-10-01

Austfonna (8120 km2) is by far the largest ice mass in the Svalbard archipelago. There is considerable uncertainty about its current state of balance and its possible response to climate change. Over the 2004/05 period, we collected continuous meteorological data series from the ice cap, performed mass-balance measurements using a network of stakes distributed across the ice cap and mapped the distribution of snow accumulation using ground-penetrating radar along several profile lines. These data are used to drive and test a model of the surface mass balance. The spatial accumulation pattern was derived from the snow depth profiles using regression techniques, and ablation was calculated using a temperature-index approach. Model parameters were calibrated using the available field data. Parameter calibration was complicated by the fact that different parameter combinations yield equally acceptable matches to the stake data while the resulting calculated net mass balance differs considerably. Testing model results against multiple criteria is an efficient method to cope with non-uniqueness. In doing so, a range of different data and observations was compared to several different aspects of the model results. We find a systematic underestimation of net balance for parameter combinations that predict observed ice ablation, which suggests that refreezing processes play an important role. To represent these effects in the model, a simple PMAX approach was included in its formulation. Used as a diagnostic tool, the model suggests that the surface mass balance for the period 29 April 2004 to 23 April 2005 was negative (-318 mm w.e.).

Remote Sensing Estimates of Glacier Mass Balance Changes in the Himalayas of Nepal

NASA Astrophysics Data System (ADS)

Ambinakudige, S.; Joshi, K.

2011-12-01

Mass balance changes of glaciers are important indicators of climate change. There are only 30 'reference' glaciers in the world that have continuous mass balance data with world glacier monitoring service since 1976. Especially, Himalayan glaciers are conspicuously absent from global mass balance records. This shows the urgent need for mass balance data for glaciers throughout the world. In this study, we estimated mass balance of some major glaciers in the Sagarmatha National Park (SNP) in Nepal using remote sensing applications. The SNP is one of the densest glaciated regions in the Himalayan range consisting approximately 296 glacial lakes. The region has experienced several glacial lake outburst floods (GLOFs) in recent years, causing extensive damage to local infrastructure and loss of human life. In general, mass balance is determined at seasonal or yearly intervals. Because of the rugged and difficult terrain of the Himalayan region, there are only a few field based measurements of mass balance available. Moreover, there are only few cases where the applications of remote sensing methods were used to calculate mass balance of the Himalayan glaciers due to the lack of accurate elevation data. Studies have shown that estimations of mass balance using remote sensing applications were within the range of field-based mass balance measurements from the same period. This study used ASTER VNIR, 3N (nadir view) and 3B (backward view) bands to generate Digital Elevation Models (DEMs) for the SNP area. 3N and 3B bands generate an along track stereo pair with a base-to-height (B/H) ratio of about 0.6. Accurate measurement of ground control points (GCPs), their numbers and distribution are important inputs in creating accurate DEMs. Because of the availability of topographic maps for this area, we were able to provide very accurate GCPs, in sufficient numbers and distribution. We created DEMs for the years 2002, 2003, 2004 and 2005 using ENVI DEM extraction tool. Bands 3N and 3B were used as left and right images respectively in the process of creating the DEM. Minimum elevation in these images was 1500m and maximum elevation was 8550m. Coordinates and elevation values from topographic maps in the non-glaciated region were used as GCPs while creating absolute DEMs. Considering the high terrain of the study area, we used large number of GCPs, tie points, higher windows search area, and high terrain parameters to improve DEM accuracy. Since these images were acquired in September, the accumulation area was clearly visible. The Global land ice measurement (GLIMS) database which is maintained at the National Snow and Ice Data Center (NSIDC) was used to delineate glacier boundaries. The differences between the elevations in consecutive years in the accumulation area were calculated using raster calculator. The total elevation differences were then multiplied by the area to estimate the change in volume. Density of ice used in mass balance calculation was 900kg per sq. meters. The result indicated that while there was a decrease in mass balance of some glaciers, some showed an increase in mass balance during the study period. The study helped to develop a data on mass balance change in some major glaciers in the Himalayas.

Variable Acceleration Force Calibration System (VACS)

NASA Technical Reports Server (NTRS)

Rhew, Ray D.; Parker, Peter A.; Johnson, Thomas H.; Landman, Drew

2014-01-01

Conventionally, force balances have been calibrated manually, using a complex system of free hanging precision weights, bell cranks, and/or other mechanical components. Conventional methods may provide sufficient accuracy in some instances, but are often quite complex and labor-intensive, requiring three to four man-weeks to complete each full calibration. To ensure accuracy, gravity-based loading is typically utilized. However, this often causes difficulty when applying loads in three simultaneous, orthogonal axes. A complex system of levers, cranks, and cables must be used, introducing increased sources of systematic error, and significantly increasing the time and labor intensity required to complete the calibration. One aspect of the VACS is a method wherein the mass utilized for calibration is held constant, and the acceleration is changed to thereby generate relatively large forces with relatively small test masses. Multiple forces can be applied to a force balance without changing the test mass, and dynamic forces can be applied by rotation or oscillating acceleration. If rotational motion is utilized, a mass is rigidly attached to a force balance, and the mass is exposed to a rotational field. A large force can be applied by utilizing a large rotational velocity. A centrifuge or rotating table can be used to create the rotational field, and fixtures can be utilized to position the force balance. The acceleration may also be linear. For example, a table that moves linearly and accelerates in a sinusoidal manner may also be utilized. The test mass does not have to move in a path that is parallel to the ground, and no re-leveling is therefore required. Balance deflection corrections may be applied passively by monitoring the orientation of the force balance with a three-axis accelerometer package. Deflections are measured during each test run, and adjustments with respect to the true applied load can be made during the post-processing stage. This paper will present the development and testing of the VASC concept.

Invited article: Time accurate mass flow measurements of solid-fueled systems.

PubMed

Olliges, Jordan D; Lilly, Taylor C; Joslyn, Thomas B; Ketsdever, Andrew D

2008-10-01

A novel diagnostic method is described that utilizes a thrust stand mass balance (TSMB) to directly measure time-accurate mass flow from a solid-fuel thruster. The accuracy of the TSMB mass flow measurement technique was demonstrated in three ways including the use of an idealized numerical simulation, verifying a fluid mass calibration with high-speed digital photography, and by measuring mass loss in more than 30 hybrid rocket motor firings. Dynamic response of the mass balance was assessed through weight calibration and used to derive spring, damping, and mass moment of inertia coefficients for the TSMB. These dynamic coefficients were used to determine the mass flow rate and total mass loss within an acrylic and gaseous oxygen hybrid rocket motor firing. Intentional variations in the oxygen flow rate resulted in corresponding variations in the total propellant mass flow as expected. The TSMB was optimized to determine mass losses of up to 2.5 g and measured total mass loss to within 2.5% of that calculated by a NIST-calibrated digital scale. Using this method, a mass flow resolution of 0.0011 g/s or 2% of the average mass flow in this study has been achieved.

Invited Article: Time accurate mass flow measurements of solid-fueled systems

NASA Astrophysics Data System (ADS)

Olliges, Jordan D.; Lilly, Taylor C.; Joslyn, Thomas B.; Ketsdever, Andrew D.

2008-10-01

A novel diagnostic method is described that utilizes a thrust stand mass balance (TSMB) to directly measure time-accurate mass flow from a solid-fuel thruster. The accuracy of the TSMB mass flow measurement technique was demonstrated in three ways including the use of an idealized numerical simulation, verifying a fluid mass calibration with high-speed digital photography, and by measuring mass loss in more than 30 hybrid rocket motor firings. Dynamic response of the mass balance was assessed through weight calibration and used to derive spring, damping, and mass moment of inertia coefficients for the TSMB. These dynamic coefficients were used to determine the mass flow rate and total mass loss within an acrylic and gaseous oxygen hybrid rocket motor firing. Intentional variations in the oxygen flow rate resulted in corresponding variations in the total propellant mass flow as expected. The TSMB was optimized to determine mass losses of up to 2.5 g and measured total mass loss to within 2.5% of that calculated by a NIST-calibrated digital scale. Using this method, a mass flow resolution of 0.0011 g/s or 2% of the average mass flow in this study has been achieved.

Thermal Characterization of the Air Force Institute of Technology Solar Simulation Thermal Vacuum Chamber

DTIC Science & Technology

2014-03-27

mass and surface area, Equation 12 demonstrates an energy balance for the material, assuming the rest of the surfaces of the material are isothermal...radiation in order to dissipate heat from 18 the spacecraft [8]. As discussed in the system thermal energy balance defined previously, emission of IR... energy balance calculations will be utilized. The Monte Carlo/Ray Trace Radiation Method The Monte Carlo/Ray Trace method is utilized in order to

Sensitivity of annual mass balance gradient and Hypsometry to the changing climate: the case of Dokriani Glacier, central Himalaya, India

NASA Astrophysics Data System (ADS)

Pratap, B.

2015-12-01

The glacier mass balance is undelayed, unfiltered and direct method to assess the impact of climate change on the glaciers. Many studies suggest that some of the Himalayan glaciers have lost their mass at an increased rate during the past few decades. Furthermore, the mass balance gradient and hypsometric analysis are important to understand the glacier response towards climatic perturbations. Our long term in-situ monitoring on the Dokriani Glacier provides great insights to understand the variability in central Himalayan glaciers. We report the relationship between glacier hypsometry and annual mass balance gradient (12 years) to understand the glacier's response towards climate change. Dokriani Glacier in the Bhagirathi basin is a small (7 km2) NNW exposed glacier in the western part of central Himalaya, India. The study analysed the annual balance, mass balance gradient and length changes observed during first decade of 21st century (2007-2013) and compare with the previous observations of 1990s (1992-2000). A large spatial variability in the mass balance gradients of two different periods has been observed. The equilibrium-line altitude (ELA) was fluctuated between 5000 and 5100 m a.s.l. and the derived time averaged ELA (ELAn) and balance budget ELA (ELA0) were 5075 and 4965 m a.s.l respectively during 1992-2013. The observed time-averaged accumulation-area ratio (AARn) and balance budget AAR (AAR0) were 0.67 and 0.72 respectively during 1992-2013. The higher value of AAR comprises due to flat and broader accumulation area (4.50 km2) of the glacier. Although, having larger accumulation area, the glacier has faced strong mass wasting with average annual ablation of -1.82 m w.e. a-1 in the ablation zone as compare to residual average annual accumulation of 0.41 m w.e. a-1. Based on the annual mass balance series (12 years) Dokriani Glacier has continuous negative annual balances with monotonically negative cumulative mass loss of -3.86 m w.e with the average loss of -0.32 m w.e a-1. Dokriani Glacier also showed continues recession from 1992 to present. Snout was ascended 95 m a.s.l. from an elevation of 3870 m a.s.l. in 1992 to an elevation of 3965 m a.s.l. in 2013. The progressive retreat of the glacier affects its extension and volume and covered by continuous enhancement of debris in the lower ablation zone.

Ultra-trace level determination of diquat and paraquat residues in surface and drinking water using ion-pair liquid chromatography with tandem mass spectrometry: a comparison of direct injection and solid-phase extraction methods.

PubMed

Oh, Jin-Aa; Lee, Jun-Bae; Lee, Soo-Hyung; Shin, Ho-Sang

2014-10-01

Direct injection and solid-phase extraction methods for the determination of diquat and paraquat in surface and drinking water were developed using liquid chromatography with tandem mass spectrometry. The signal intensities of analytes based on six ion-pairing reagents were compared with each other, and 12.5 mM nonafluoropentanoic acid was selected as the best suited amongst them. A clean-up method was developed using Oasis hydrophilic-lipophilic balance; this was compared to the direct injection method, with respect to limits of detection, interference, precision, and accuracy. Limits of quantification of diquat and paraquat were 0.03 and 0.01 μg/L using the direct injection method, and 0.002 and 0.001 μg/L using the hydrophilic-lipophilic balance method. When the hydrophilic-lipophilic balance method was used to analyze target compounds in 114 surface water and 30 drinking water samples, paraquat and diquat were detected within a concentration range of 0.001-0.12 and 0.002-0.038 μg/L in surface water, respectively. When the direct injection method was used to analyze target compounds in the same samples, the detected concentrations of paraquat and diquat were within 25% in samples being >0.015 μg/L using the hydrophilic-lipophilic balance method. The liquid chromatography with tandem mass spectrometry method using direct injection can thus be used for routine monitoring of paraquat and diquat in surface and drinking water. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Reconciled Estimate of Ice-Sheet Mass Balance

NASA Technical Reports Server (NTRS)

Shepherd, Andrew; Ivins, Erik R.; Geruo, A.; Barletta, Valentia R.; Bentley, Mike J.; Bettadpur, Srinivas; Briggs, Kate H.; Bromwich, David H.; Forsberg, Rene; Galin, Natalia;

Comparison of two methods for estimating base flow in selected reaches of the South Platte River, Colorado

USGS Publications Warehouse

Capesius, Joseph P.; Arnold, L. Rick

2012-01-01

The Mass Balance results were quite variable over time such that they appeared suspect with respect to the concept of groundwater flow as being gradual and slow. The large degree of variability in the day-to-day and month-to-month Mass Balance results is likely the result of many factors. These factors could include ungaged stream inflows or outflows, short-term streamflow losses to and gains from temporary bank storage, and any lag in streamflow accounting owing to streamflow lag time of flow within a reach. The Pilot Point time series results were much less variable than the Mass Balance results and extreme values were effectively constrained. Less day-to-day variability, smaller magnitude extreme values, and smoother transitions in base-flow estimates provided by the Pilot Point method are more consistent with a conceptual model of groundwater flow being gradual and slow. The Pilot Point method provided a better fit to the conceptual model of groundwater flow and appeared to provide reasonable estimates of base flow.

Finding the Density of Objects without Measuring Mass and Volume

ERIC Educational Resources Information Center

Mumba, Frackson; Tsige, Mesfin

2007-01-01

A simple method based on the moment of forces and Archimedes' principle is described for finding density without measuring the mass and volume of an object. The method involves balancing two unknown objects of masses M[subscript 1] and M[subscript 2] on each side of a pivot on a metre rule and measuring their corresponding moment arms. The object…

Using an SLR inversion to measure the mass balance of Greenland before and during GRACE

NASA Astrophysics Data System (ADS)

Bonin, Jennifer

2016-04-01

The GRACE mission has done an admirable job of measuring large-scale mass changes over Greenland since its launch in 2002. However before that time, measurements of large-scale ice mass balance were few and far between, leading to a lack of baseline knowledge. High-quality Satellite Laser Ranging (SLR) data existed a decade earlier, but normally has too low a spatial resolution to be used for this purpose. I demonstrate that a least squares inversion technique can reconstitute the SLR data and use it to measure ice loss over Greenland. To do so, I first simulate the problem by degrading today's GRACE data to a level comparable with SLR, then demonstrating that the inversion can re-localize Greenland's contribution to the low-resolution signal, giving an accurate time series of mass change over all of Greenland which compares well with the full-resolution GRACE estimates. I then utilize that method on the actual SLR data, resulting in an independent 1994-2014 time series of mass change over Greenland. I find favorable agreement between the pure-SLR inverted results and the 2012 Ice-sheet Mass Balance Inter-comparison Exercise (IMBIE) results, which are largely based on the "input-output" modeling method before GRACE's launch.

Changing pattern of ice flow and mass balance for glaciers discharging into the Larsen A and B embayments, Antarctic Peninsula, 2011 to 2016

NASA Astrophysics Data System (ADS)

Rott, Helmut; Abdel Jaber, Wael; Wuite, Jan; Scheiblauer, Stefan; Floricioiu, Dana; Melchior van Wessem, Jan; Nagler, Thomas; Miranda, Nuno; van den Broeke, Michiel R.

2018-04-01

We analysed volume change and mass balance of outlet glaciers on the northern Antarctic Peninsula over the periods 2011 to 2013 and 2013 to 2016, using high-resolution topographic data from the bistatic interferometric radar satellite mission TanDEM-X. Complementary to the geodetic method that applies DEM differencing, we computed the net mass balance of the main outlet glaciers using the mass budget method, accounting for the difference between the surface mass balance (SMB) and the discharge of ice into an ocean or ice shelf. The SMB values are based on output of the regional climate model RACMO version 2.3p2. To study glacier flow and retrieve ice discharge we generated time series of ice velocity from data from different satellite radar sensors, with radar images of the satellites TerraSAR-X and TanDEM-X as the main source. The study area comprises tributaries to the Larsen A, Larsen Inlet and Prince Gustav Channel embayments (region A), the glaciers calving into the Larsen B embayment (region B) and the glaciers draining into the remnant part of the Larsen B ice shelf in Scar Inlet (region C). The glaciers of region A, where the buttressing ice shelf disintegrated in 1995, and of region B (ice shelf break-up in 2002) show continuing losses in ice mass, with significant reduction of losses after 2013. The mass balance numbers for the grounded glacier area of region A are -3.98 ± 0.33 Gt a-1 from 2011 to 2013 and -2.38 ± 0.18 Gt a-1 from 2013 to 2016. The corresponding numbers for region B are -5.75 ± 0.45 and -2.32 ± 0.25 Gt a-1. The mass balance in region C during the two periods was slightly negative, at -0.54 ± 0.38 Gt a-1 and -0.58 ± 0.25 Gt a-1. The main share in the overall mass losses of the region was contributed by two glaciers: Drygalski Glacier contributing 61 % to the mass deficit of region A, and Hektoria and Green glaciers accounting for 67 % to the mass deficit of region B. Hektoria and Green glaciers accelerated significantly in 2010-2011, triggering elevation losses up to 19.5 m a-1 on the lower terminus during the period 2011 to 2013 and resulting in a mass balance of -3.88 Gt a-1. Slowdown of calving velocities and reduced calving fluxes in 2013 to 2016 coincided with years in which ice mélange and sea ice cover persisted in proglacial fjords and bays during summer.

Antarctic Glacial Isostatic Adjustment and Ice Sheet Mass Balance using GRACE: A Report from the Ice-sheet Mass Balance Exercise (IMBIE)

NASA Astrophysics Data System (ADS)

Ivins, E. R.; Wahr, J. M.; Schrama, E. J.; Milne, G. A.; Barletta, V.; Horwath, M.; Whitehouse, P.

2012-12-01

In preparation for the Inter-govermental Panel on Climate Change: Assessment Report 5 (IPCC AR5), ESA and NASA have formed a committee of experts to perform a formal set of comparative experiments concerning space observations of ice sheet mass balance. This project began in August of 2011 and has now concluded with a report submitted for Science (Shepherd et al., 2012). The focus of the work conducted is to re-evaluate scientific reports on the mass balance of Greenland ice sheet (GIS) and Antarctic ice sheet (AIS). The most serious discrepancies have been reported for the AIS, amounting to as much as 0.9 mm/yr in discrepant sea level contribution. A direct method of determining the AIS is by space gravimetry. However, for this method to contribute to our understanding of sea level change, we require knowledge of present-day non-elastic vertical movements of bedrock in Antarctica. Quantifying the uncertainty and bias caused by lack of observational control on models of regional glacial isostatic adjustment (GIA), was a major focus for our experiments. This regional process is the most problematic error source for GRACE-determinations of ice mass balance in Antarctica. While GIA likely dominates some large vertical motions in Antarctica that are now observed with GPS (Thomas et al., 2011, GRL), interpretations still require models. The reported uncertainty for space gravimetric (GRACE) based sea level sourcing is roughly 0.20 to 0.35 mm/yr. The uncertainty is also part of the error budget for mass balances derived from altimetry measurements, though at a much lower level. Analysis of the GRACE time series using CSR RL04 (2003.0-2010.10) for AIS mass balance reveals a small trend of order +1 to -24 Gt/yr without a GIA correction. Three periods were selected over which to perform inter-comparisons (see Table). One class of GIA models, that relies primarily on far field sea level reconstructions (e.g. ICE-5G), provide a GIA correction that places AIS mass imbalance (δM) as high as -160 Gt/yr. IMBIE used an average of new models IJ05_R2 and W12a for new corrections. This new class of models is constrained by a variety of Antarctic data sets (e.g. proxy reconstructions of past ice extent, GPS estimates of vertical land motion) and provides a correction that is approximately one half to one third of that obtained from the far-field based models. As a consequence, this newer class of models gives Antarctic ice mass balance of approximately -81 ± 33 Gt/yr, or 0.225 ± 0.092 mm/yr contribution to sea-level rise. The new class of GIA models for Antarctica enhances the value of all GRACE Follow-On mission data.Mass Balance of AIS δM (Gt/yr);

A spatially resolved estimate of High Mountain Asia glacier mass balances from 2000 to 2016

NASA Astrophysics Data System (ADS)

Brun, Fanny; Berthier, Etienne; Wagnon, Patrick; Kääb, Andreas; Treichler, Désirée

2017-09-01

High Mountain Asia hosts the largest glacier concentration outside the polar regions. These glaciers are important contributors to streamflow in one of the most populated areas of the world. Past studies have used methods that can provide only regionally averaged glacier mass balances to assess the glacier contribution to rivers and sea level rise. Here we compute the mass balance for about 92% of the glacierized area of High Mountain Asia using time series of digital elevation models derived from satellite stereo-imagery. We calculate a total mass change of -16.3 +/- 3.5 Gt yr-1 (-0.18 +/- 0.04 m w.e. yr-1) between 2000 and 2016, which is less negative than most previous estimates. Region-wide mass balances vary from -4.0 +/- 1.5 Gt yr-1 (-0.62 +/- 0.23 m w.e. yr-1) in Nyainqentanglha to +1.4 +/- 0.8 Gt yr-1 (+0.14 +/- 0.08 m w.e. yr-1) in Kunlun, with large intra-regional variability of individual glacier mass balances (standard deviation within a region ~0.20 m w.e. yr-1). Specifically, our results shed light on the Nyainqentanglha and Pamir glacier mass changes, for which contradictory estimates exist in the literature. They provide crucial information for the calibration of the models used for projecting glacier response to climatic change, as these models do not capture the pattern, magnitude and intra-regional variability of glacier changes at present.

Micromechanical Oscillating Mass Balance

NASA Technical Reports Server (NTRS)

Altemir, David A. (Inventor)

1997-01-01

A micromechanical oscillating mass balance and method adapted for measuring minute quantities of material deposited at a selected location, such as during a vapor deposition process. The invention comprises a vibratory composite beam which includes a dielectric layer sandwiched between two conductive layers. The beam is positioned in a magnetic field. An alternating current passes through one conductive layers, the beam oscillates, inducing an output current in the second conductive layer, which is analyzed to determine the resonant frequency of the beam. As material is deposited on the beam, the mass of the beam increases and the resonant frequency of the beam shifts, and the mass added is determined.

Metabolite-balancing techniques vs. 13C tracer experiments to determine metabolic fluxes in hybridoma cells.

PubMed

Bonarius, H P; Timmerarends, B; de Gooijer, C D; Tramper, J

The estimation of intracellular fluxes of mammalian cells using only mass balances of the relevant metabolites is not possible because the set of linear equations defined by these mass balances is underdetermined. In order to quantify fluxes in cyclic pathways the mass balance equations can be complemented with several constraints: (1) the mass balances of co-metabolites, such as ATP or NAD(P)H, (2) linear objective functions, (3) flux data obtained by isotopic-tracer experiments. Here, these three methods are compared for the analysis of fluxes in the primary metabolism of continuously cultured hybridoma cells. The significance of different theoretical constraints and different objective functions is discussed after comparing their resulting flux distributions to the fluxes determined using 13CO2 and 13C-lactate measurements of 1 - 13C-glucose-fed hybridoma cells. Metabolic fluxes estimated using the objective functions "maximize ATP" and "maximize NADH" are relatively similar to the experimentally determined fluxes. This is consistent with the observation that cancer cells, such as hybridomas, are metabolically hyperactive, and produce ATP and NADH regardless of the need for these cofactors. Copyright 1998 John Wiley & Sons, Inc.

Chloride mass-balance method for estimating ground water recharge in arid areas: examples from western Saudi Arabia

NASA Astrophysics Data System (ADS)

Bazuhair, Abdulghaffar S.; Wood, Warren W.

1996-11-01

The chloride mass-balance method, which integrates time and aerial distribution of ground water recharge, was applied to small alluvial aquifers in the wadi systems of the Asir and Hijaz mountains in western Saudi Arabia. This application is an extension of the method shown to be suitable for estimating recharge in regional aquifers in semi-arid areas. Because the method integrates recharge in time and space it appears to be, with certain assumptions, particularly well suited for and areas with large temporal and spatial variation in recharge. In general, recharge was found to be between 3 to 4% of precipitation — a range consistent with recharge rates found in other and and semi-arid areas of the earth.

Chloride mass-balance method for estimating ground water recharge in arid areas: Examples from western Saudi Arabia

USGS Publications Warehouse

Bazuhair, A.S.; Wood, W.W.

1996-01-01

The chloride mass-balance method, which integrates time and aerial distribution of ground water recharge, was applied to small alluvial aquifers in the wadi systems of the Asir and Hijaz mountains in western Saudi Arabia. This application is an extension of the method shown to be suitable for estimating recharge in regional aquifers in semi-arid areas. Because the method integrates recharge in time and space it appears to be, with certain assumptions, particularly well suited for and areas with large temporal and spatial variation in recharge. In general, recharge was found to be between 3 to 4% of precipitation - a range consistent with recharge rates found in other arid and semi-arid areas of the earth.

Reconstruction of past equilibrium line altitude using ice extent data

NASA Astrophysics Data System (ADS)

Visnjevic, Vjeran; Herman, Frederic; Podladchikov, Yuri

2017-04-01

With the end of the Last Glacial Maximum (LGM), about 20 000 years ago, ended the most recent long-lasting cold phase in Earth's history. This last glacial advance left a strong observable imprint on the landscape, such as abandoned moraines, trimlines and other glacial geomorphic features. These features provide a valuable record of past continental climate. In particular, terminal moraines reflect the extent of glaciers and ice-caps, which itself reflects past temperature and precipitation conditions. Here we present an inverse approach, based on a Tikhonov regularization, we have recently developed to reconstruct the LGM mass balance from observed ice extent data. The ice flow model is developed using the shallow ice approximation and solved explicitly using Graphical Processing Units (GPU). The mass balance field, b, is the constrained variable defined by the ice surface S, balance rate β and the spatially variable equilibrium line altitude field (ELA): b = min (β ṡ(S(x,y)- ELA (x,y)),c). (1) where c is a maximum accumulation rate. We show that such a mass balance, and thus the spatially variable ELA field, can be inferred from the observed past ice extent and ice thickness at high resolution and very efficiently. The GPU implementation allows us solve one 1024x1024 grid points forward model run under 0.5s, which significantly reduces the time needed for our inverse method to converge. We start with synthetic test to demonstrate the method. We then apply the method to LGM ice extents of South Island of New Zealand, the Patagonian Andes, where we can see a clear influence of Westerlies on the ELA, and the European Alps. These examples show that the method is capable of constraining spatial variations in mass balance at the scale of a mountain range, and provide us with information on past continental climate.

Active vibration and balance system for closed cycle thermodynamic machines

NASA Technical Reports Server (NTRS)

Augenblick, John E. (Inventor); Peterson, Allen A. (Inventor); White, Maurice A. (Inventor); Qiu, Songgang (Inventor)

2004-01-01

An active balance system is provided for counterbalancing vibrations of an axially reciprocating machine. The balance system includes a support member, a flexure assembly, a counterbalance mass, and a linear motor or an actuator. The support member is configured for attachment to the machine. The flexure assembly includes at least one flat spring having connections along a central portion and an outer peripheral portion. One of the central portion and the outer peripheral portion is fixedly mounted to the support member. The counterbalance mass is fixedly carried by the flexure assembly along another of the central portion and the outer peripheral portion. The linear motor has one of a stator and a mover fixedly mounted to the support member and another of the stator and the mover fixedly mounted to the counterbalance mass. The linear motor is operative to axially reciprocate the counterbalance mass. A method is also provided.

Surface Mass Balance of the Columbia Glacier, Alaska, 1978 and 2010 Balance Years

USGS Publications Warehouse

O'Neel, Shad

2012-01-01

Although Columbia Glacier is one of the largest sources of glacier mass loss in Alaska, surface mass balance measurements are sparse, with only a single data set available from 1978. The dearth of surface mass-balance data prohibits partitioning of the total mass losses between dynamics and surface forcing; however, the accurate inclusion of calving glaciers into predictive models requires both dynamic and climatic forcing of total mass balance. During 2010, the U.S. Geological Survey collected surface balance data at several locations distributed over the surface of Columbia Glacier to estimate the glacier-wide annual balance for balance year 2010 using the 2007 area-altitude distribution. This report also summarizes data collected in 1978, calculates the 1978 annual surface balance, and uses these observations to constrain the 2010 values, particularly the shape of the balance profile. Both years exhibit balances indicative of near-equilibrium surface mass-balance conditions, and demonstrate the importance of dynamic processes during the rapid retreat.

Mountain glaciers vs Ice sheet in Greenland - learning from a new monitoring site in West Greenland

NASA Astrophysics Data System (ADS)

Abermann, Jakob; van As, Dirk; Wacker, Stefan; Langley, Kirsty

2017-04-01

Only 5 out of the 20.000 peripheral glaciers and ice caps surrounding Greenland are currently monitored due to logistical challenges and despite their significance for sea level rise. Large spatial coast-to-icesheet mass and energy balance gradients limit simple upscaling methods from ice-sheet observations, which builds the motivation for this study. We present results from a new mass and energy balance time series at Qasigiannguit glacier (64°09'N; 51°21'W) in Southwest Greenland. Inter-annual variability is discussed and the surface energy balance over two summers is quantified and a ranking of the main drivers performed. We find that short-wave net radiation is by far the most dominant energy source during summer, followed by similar amounts of net longwave radiation and sensible heat, respectively. We then relate these observations to synchronous measurements at similar latitude on an outlet glacier of the ice sheet a mere 100 km away. We find very pronounced horizontal surface mass balance gradients, with generally more positive values closer to the coast. We conclude that despite minor differences of atmospheric parameters (i.e. humidity, radiation, and temperature) the main reason for the strongly different signal is a pronounced winter precipitation gradient that translates in a different duration of ice exposure and through that an albedo gradient. Modelled energy balance gradients converted into mass changes show good agreement to measured surface mass balance gradients and we explore a latitudinal signal of these findings.

Balance Calibration – A Method for Assigning a Direct-Reading Uncertainty to an Electronic Balance.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mike Stears

2010-07-01

Paper Title: Balance Calibration – A method for assigning a direct-reading uncertainty to an electronic balance. Intended Audience: Those who calibrate or use electronic balances. Abstract: As a calibration facility, we provide on-site (at the customer’s location) calibrations of electronic balances for customers within our company. In our experience, most of our customers are not using their balance as a comparator, but simply putting an unknown quantity on the balance and reading the displayed mass value. Manufacturer’s specifications for balances typically include specifications such as readability, repeatability, linearity, and sensitivity temperature drift, but what does this all mean when themore » balance user simply reads the displayed mass value and accepts the reading as the true value? This paper discusses a method for assigning a direct-reading uncertainty to a balance based upon the observed calibration data and the environment where the balance is being used. The method requires input from the customer regarding the environment where the balance is used and encourages discussion with the customer regarding sources of uncertainty and possible means for improvement; the calibration process becomes an educational opportunity for the balance user as well as calibration personnel. This paper will cover the uncertainty analysis applied to the calibration weights used for the field calibration of balances; the uncertainty is calculated over the range of environmental conditions typically encountered in the field and the resulting range of air density. The temperature stability in the area of the balance is discussed with the customer and the temperature range over which the balance calibration is valid is decided upon; the decision is based upon the uncertainty needs of the customer and the desired rigor in monitoring by the customer. Once the environmental limitations are decided, the calibration is performed and the measurement data is entered into a custom spreadsheet. The spreadsheet uses measurement results, along with the manufacturer’s specifications, to assign a direct-read measurement uncertainty to the balance. The fact that the assigned uncertainty is a best-case uncertainty is discussed with the customer; the assigned uncertainty contains no allowance for contributions associated with the unknown weighing sample, such as density, static charges, magnetism, etc. The attendee will learn uncertainty considerations associated with balance calibrations along with one method for assigning an uncertainty to a balance used for non-comparison measurements.« less

South Cascade (USA/North Cascades)

USGS Publications Warehouse

Bidlake, William R.

2011-01-01

The U.S. Geological Survey has closely monitored this temperate mountain glacier since the late 1950s. During 1958-2007, the glacier retreated about 0.7 km and shrank in area from 2.71 to 1.73 km2, although part of the area change was due to separation of contributing ice bodies from the main glacier. Maximum and average glacier thicknesses are about 170 and 80 m, respectively. Year-to-year variations of snow accumulation amounts on the glacier are largely attributable to the regional maritime climate and fluctuating climate conditions of the North Pacific Ocean. Long-term-average precipitation is about 4500 mm and most of that falls as snow during October through May. Average annual air temperature at 1,900 m altitude (the approximate ELA0) was estimated to be 1.6°C during 2000-2009. Mass balances are computed yearly by the direct glaciological method. Mass balances measured at selected locations are used in an interpolation and extrapolation procedure that computes the mass balance at each point in the glacier surface altitude grid. The resulting mass balance grid is averaged to obtain glacier mass balances. Additionally, the geodetic method has been applied to compute glacier net balances in 1970, 1975, 1977, 1979-80, and 1985-97. Winter snow accumulation on the glacier during 2007/08 and 2008/09 was larger than the long-term (1959-2009) average. The 2007/08 preliminary summer balance (-3510 mm w.e.) was slightly more negative than the long-term average and this yielded a preliminary 2007/08 net balance (-290 mm w.e.), which was less negative than the average for the period of record (-600 mm w.e.). Summer 2009 was uncommonly warm and the preliminary 2008/09 summer balance (-4980 mm w.e.) was more negative than any on record for the glacier. The 2008/09 glacier net balance (-1860 mm w.e.) was among the 10 most negative for the period of net balance record (1953-2009). Material presented here is preliminary in nature and presented prior to final review. These data and information are provided with the understanding that they are not guaranteed to be correct or complete. Users are cautioned to consider carefully the provisional nature of these data and information before using them for decisions that concern personal or public safety or the conduct of business that involves substantial monetary or operational consequences. Conclusions drawn from, or actions undertaken on the basis of, such data and information are the sole responsibility of the user.

Greenland Ice Sheet Mass Balance

NASA Technical Reports Server (NTRS)

Reeh, N.

1984-01-01

Mass balance equation for glaciers; areal distribution and ice volumes; estimates of actual mass balance; loss by calving of icebergs; hydrological budget for Greenland; and temporal variations of Greenland mass balance are examined.

Mass, energy and material balances of SRF production process. Part 2: SRF produced from construction and demolition waste.

PubMed

Nasrullah, Muhammad; Vainikka, Pasi; Hannula, Janne; Hurme, Markku; Kärki, Janne

2014-11-01

In this work, the fraction of construction and demolition waste (C&D waste) complicated and economically not feasible to sort out for recycling purposes is used to produce solid recovered fuel (SRF) through mechanical treatment (MT). The paper presents the mass, energy and material balances of this SRF production process. All the process streams (input and output) produced in MT waste sorting plant to produce SRF from C&D waste are sampled and treated according to CEN standard methods for SRF. Proximate and ultimate analysis of these streams is performed and their composition is determined. Based on this analysis and composition of process streams their mass, energy and material balances are established for SRF production process. By mass balance means the overall mass flow of input waste material stream in the various output streams and material balances mean the mass flow of components of input waste material stream (such as paper and cardboard, wood, plastic (soft), plastic (hard), textile and rubber) in the various output streams of SRF production process. The results from mass balance of SRF production process showed that of the total input C&D waste material to MT waste sorting plant, 44% was recovered in the form of SRF, 5% as ferrous metal, 1% as non-ferrous metal, and 28% was sorted out as fine fraction, 18% as reject material and 4% as heavy fraction. The energy balance of this SRF production process showed that of the total input energy content of C&D waste material to MT waste sorting plant, 74% was recovered in the form of SRF, 16% belonged to the reject material and rest 10% belonged to the streams of fine fraction and heavy fraction. From the material balances of this process, mass fractions of plastic (soft), paper and cardboard, wood and plastic (hard) recovered in the SRF stream were 84%, 82%, 72% and 68% respectively of their input masses to MT plant. A high mass fraction of plastic (PVC) and rubber material was found in the reject material stream. Streams of heavy fraction and fine fraction mainly contained non-combustible material (such as stone/rock, sand particles and gypsum material). Copyright © 2014 Elsevier Ltd. All rights reserved.

Mass, energy and material balances of SRF production process. Part 1: SRF produced from commercial and industrial waste.

PubMed

Nasrullah, Muhammad; Vainikka, Pasi; Hannula, Janne; Hurme, Markku; Kärki, Janne

2014-08-01

This paper presents the mass, energy and material balances of a solid recovered fuel (SRF) production process. The SRF is produced from commercial and industrial waste (C&IW) through mechanical treatment (MT). In this work various streams of material produced in SRF production process are analyzed for their proximate and ultimate analysis. Based on this analysis and composition of process streams their mass, energy and material balances are established for SRF production process. Here mass balance describes the overall mass flow of input waste material in the various output streams, whereas material balance describes the mass flow of components of input waste stream (such as paper and cardboard, wood, plastic (soft), plastic (hard), textile and rubber) in the various output streams of SRF production process. A commercial scale experimental campaign was conducted on an MT waste sorting plant to produce SRF from C&IW. All the process streams (input and output) produced in this MT plant were sampled and treated according to the CEN standard methods for SRF: EN 15442 and EN 15443. The results from the mass balance of SRF production process showed that of the total input C&IW material to MT waste sorting plant, 62% was recovered in the form of SRF, 4% as ferrous metal, 1% as non-ferrous metal and 21% was sorted out as reject material, 11.6% as fine fraction, and 0.4% as heavy fraction. The energy flow balance in various process streams of this SRF production process showed that of the total input energy content of C&IW to MT plant, 75% energy was recovered in the form of SRF, 20% belonged to the reject material stream and rest 5% belonged with the streams of fine fraction and heavy fraction. In the material balances, mass fractions of plastic (soft), plastic (hard), paper and cardboard and wood recovered in the SRF stream were 88%, 70%, 72% and 60% respectively of their input masses to MT plant. A high mass fraction of plastic (PVC), rubber material and non-combustibles (such as stone/rock and glass particles), was found in the reject material stream. Copyright © 2014 Elsevier Ltd. All rights reserved.

Sea level rise from the Greenland Ice Sheet during the Eemian interglacial: Review of previous work with focus on the surface mass balance

NASA Astrophysics Data System (ADS)

Plach, Andreas; Hestnes Nisancioglu, Kerim

2016-04-01

The contribution from the Greenland Ice Sheet (GIS) to the global sea level rise during the Eemian interglacial (about 125,000 year ago) was the focus of many studies in the past. A main reason for the interest in this period is the considerable warmer climate during the Eemian which is often seen as an equivalent for possible future climate conditions. Simulated sea level rise during the Eemian can therefore be used to better understand a possible future sea level rise. The most recent assessment report of the Intergovernmental Panel on Climate Change (IPCC AR5) gives an overview of several studies and discusses the possible implications for a future sea level rise. The report also reveals the big differences between these studies in terms of simulated GIS extent and corresponding sea level rise. The present study gives a more exhaustive review of previous work discussing sea level rise from the GIS during the Eemian interglacial. The smallest extents of the GIS simulated by various authors are shown and summarized. A focus is thereby given to the methods used to calculate the surface mass balance. A hypothesis of the present work is that the varying results of the previous studies can largely be explained due to the various methods used to calculate the surface mass balance. In addition, as a first step for future work, the surface mass balance of the GIS for a proxy-data derived forcing ("index method") and a direct forcing with a General Circulation Model (GCM) are shown and discussed.

Mass, energy and material balances of SRF production process. Part 3: solid recovered fuel produced from municipal solid waste.

PubMed

Nasrullah, Muhammad; Vainikka, Pasi; Hannula, Janne; Hurme, Markku; Kärki, Janne

2015-02-01

This is the third and final part of the three-part article written to describe the mass, energy and material balances of the solid recovered fuel production process produced from various types of waste streams through mechanical treatment. This article focused the production of solid recovered fuel from municipal solid waste. The stream of municipal solid waste used here as an input waste material to produce solid recovered fuel is energy waste collected from households of municipality. This article presents the mass, energy and material balances of the solid recovered fuel production process. These balances are based on the proximate as well as the ultimate analysis and the composition determination of various streams of material produced in a solid recovered fuel production plant. All the process streams are sampled and treated according to CEN standard methods for solid recovered fuel. The results of the mass balance of the solid recovered fuel production process showed that 72% of the input waste material was recovered in the form of solid recovered fuel; 2.6% as ferrous metal, 0.4% as non-ferrous metal, 11% was sorted as rejects material, 12% as fine faction and 2% as heavy fraction. The energy balance of the solid recovered fuel production process showed that 86% of the total input energy content of input waste material was recovered in the form of solid recovered fuel. The remaining percentage (14%) of the input energy was split into the streams of reject material, fine fraction and heavy fraction. The material balances of this process showed that mass fraction of paper and cardboard, plastic (soft) and wood recovered in the solid recovered fuel stream was 88%, 85% and 90%, respectively, of their input mass. A high mass fraction of rubber material, plastic (PVC-plastic) and inert (stone/rock and glass particles) was found in the reject material stream. © The Author(s) 2014.

A comparative uncertainty study of the calibration of macrolide antibiotic reference standards using quantitative nuclear magnetic resonance and mass balance methods.

PubMed

Liu, Shu-Yu; Hu, Chang-Qin

2007-10-17

This study introduces the general method of quantitative nuclear magnetic resonance (qNMR) for the calibration of reference standards of macrolide antibiotics. Several qNMR experimental conditions were optimized including delay, which is an important parameter of quantification. Three kinds of macrolide antibiotics were used to validate the accuracy of the qNMR method by comparison with the results obtained by the high performance liquid chromatography (HPLC) method. The purities of five common reference standards of macrolide antibiotics were measured by the 1H qNMR method and the mass balance method, respectively. The analysis results of the two methods were compared. The qNMR is quick and simple to use. In a new medicine research and development process, qNMR provides a new and reliable method for purity analysis of the reference standard.

Tuning the Stiffness Balance Using Characteristic Frequencies as a Criterion for a Superconducting Gravity Gradiometer.

PubMed

Liu, Xikai; Ma, Dong; Chen, Liang; Liu, Xiangdong

2018-02-08

Tuning the stiffness balance is crucial to full-band common-mode rejection for a superconducting gravity gradiometer (SGG). A reliable method to do so has been proposed and experimentally tested. In the tuning scheme, the frequency response functions of the displacement of individual test mass upon common-mode accelerations were measured and thus determined a characteristic frequency for each test mass. A reduced difference in characteristic frequencies between the two test masses was utilized as the criterion for an effective tuning. Since the measurement of the characteristic frequencies does not depend on the scale factors of displacement detection, stiffness tuning can be done independently. We have tested this new method on a single-component SGG and obtained a reduction of two orders of magnitude in stiffness mismatch.

Electrode Mass Balancing as an Inexpensive and Simple Method to Increase the Capacitance of Electric Double-Layer Capacitors

PubMed Central

Andres, Britta; Engström, Ann-Christine; Blomquist, Nicklas; Forsberg, Sven; Dahlström, Christina; Olin, Håkan

2016-01-01

Symmetric electric double-layer capacitors (EDLCs) have equal masses of the same active material in both electrodes. However, having equal electrode masses may prevent the EDLC to have the largest possible specific capacitance if the sizes of the hydrated anions and cations in the electrolyte differ because the electrodes and the electrolyte may not be completely utilized. Here we demonstrate how this issue can be resolved by mass balancing. If the electrode masses are adjusted according to the size of the ions, one can easily increase an EDLC’s specific capacitance. To that end, we performed galvanostatic cycling to measure the capacitances of symmetric EDLCs with different electrode mass ratios using four aqueous electrolytes— Na2SO4, H2SO4, NaOH, and KOH (all with a concentration of 1 M)—and compared these to the theoretical optimal electrode mass ratio that we calculated using the sizes of the hydrated ions. Both the theoretical and experimental values revealed lower-than-1 optimal electrode ratios for all electrolytes except KOH. The largest increase in capacitance was obtained for EDLCs with NaOH as electrolyte. Specifically, we demonstrate an increase of the specific capacitance by 8.6% by adjusting the electrode mass ratio from 1 to 0.86. Our findings demonstrate that electrode mass balancing is a simple and inexpensive method to increase the capacitance of EDLCs. Furthermore, our results imply that one can reduce the amount of unused material in EDLCs and thus decrease their weight, volume and cost. PMID:27658253

Recent changes in equilibrium line altitudes of glaciers in the Chandra-Bhaga Catchments, the Western Himalaya

NASA Astrophysics Data System (ADS)

Kumari, R.; Vijay, S.; Banerjee, A.; Singh, G.

2017-12-01

Abstract: Climatic forcing affects a glacier through a change in the corresponding equilibrium line altitude (ELA). Many approximate methods are available in the literature for estimating ELA of glaciers that are in a steady state. Some of the rudimentary methods e.g. Toe-to-Headwall-Ratio method or mid-point elevation methods are based solely on the elevation range of the glacier cover, and ignore the variations in slope, valley width or the mass-balance profile. The mean-elevation method is more accurate in that it takes into account the glacier hypsometry. In this study, we extend this method to estimate the ELA of a glacier that is not in a steady state. We assume a linear mass-balance profile, and utilize geodetic mass balance and hypsometry of the glacier to obtain ELA. This method is generally useful to track, for example, the spatial pattern of recent ELA changes in a given region. We apply the above method to 46 debris-free glaciers in the Chandra-Bhaga catchments, the Western Himalaya, to understand the regional ELA forcing during 2000 to 2012. Shuttle Radar Topographic Mission (2000) and TanDEM-X (2012) digital elevation model (DEM) are used to get elevation data. A strong correlation (r2=0.90 and p<0.001) of the estimated ELAs with the corresponding end-of-summer-snowline-elevation data derived from cloud-free Landsat images validates our method. Our estimate for the recent ELA of Chhota shigri Glacier from the region are consistent with published glaciological ELA values. On a regional scale, the estimated ELAs are negatively correlated (r2= 0.66 and p<0.001) with the mean Tropical Rainfall Measuring Mission (TRMM 2b31) precipitation data. This implies a strong control of local precipitation on glacier mass balance profile, with 18 +/- 2 m rise of ELA per 10 mm/year reduction in rainfall. We shall also discuss the regional patterns of the changes in transient ELA between 2000 and 2012.

Temporal and spatial variabilities of Antarctic ice mass changes inferred by GRACE in a Bayesian framework

NASA Astrophysics Data System (ADS)

Wang, L.; Davis, J. L.; Tamisiea, M. E.

2017-12-01

The Antarctic ice sheet (AIS) holds about 60% of all fresh water on the Earth, an amount equivalent to about 58 m of sea-level rise. Observation of AIS mass change is thus essential in determining and predicting its contribution to sea level. While the ice mass loss estimates for West Antarctica (WA) and the Antarctic Peninsula (AP) are in good agreement, what the mass balance over East Antarctica (EA) is, and whether or not it compensates for the mass loss is under debate. Besides the different error sources and sensitivities of different measurement types, complex spatial and temporal variabilities would be another factor complicating the accurate estimation of the AIS mass balance. Therefore, a model that allows for variabilities in both melting rate and seasonal signals would seem appropriate in the estimation of present-day AIS melting. We present a stochastic filter technique, which enables the Bayesian separation of the systematic stripe noise and mass signal in decade-length GRACE monthly gravity series, and allows the estimation of time-variable seasonal and inter-annual components in the signals. One of the primary advantages of this Bayesian method is that it yields statistically rigorous uncertainty estimates reflecting the inherent spatial resolution of the data. By applying the stochastic filter to the decade-long GRACE observations, we present the temporal variabilities of the AIS mass balance at basin scale, particularly over East Antarctica, and decipher the EA mass variations in the past decade, and their role in affecting overall AIS mass balance and sea level.

Development of mass measurement equipment using an electronic mass-comparator for gravimetric preparation of reference gas mixtures

NASA Astrophysics Data System (ADS)

Matsumoto, Nobuhiro; Watanabe, Takuro; Maruyama, Masaaki; Horimoto, Yoshiyuki; Maeda, Tsuneaki; Kato, Kenji

2004-06-01

The gravimetric method is the most popular method for preparing reference gas mixtures with high accuracy. We have designed and manufactured novel mass measurement equipment for gravimetric preparation of reference gas mixtures. This equipment consists of an electronic mass-comparator with a maximum capacity of 15 kg and readability of 1 mg and an automatic cylinder exchanger. The structure of this equipment is simpler and the cost is much lower than a conventional mechanical knife-edge type large balance used for gravimetric preparation of primary gas mixtures in Japan. This cylinder exchanger can mount two cylinders alternatively on the weighing pan of the comparator. In this study, the performance of the equipment has been evaluated. At first, the linearity and repeatability of the mass measurement were evaluated using standard mass pieces. Then, binary gas mixtures of propane and nitrogen were prepared and compared with those prepared with the conventional knife-edge type balance. The comparison resulted in good consistency at the compatibility criterion described in ISO6143:2001.

Investigation on Glacier Thinning in Baspa, Western Himalaya.

NASA Astrophysics Data System (ADS)

S, P.; Kulkarni, A. V.; Bhushan, S.

2017-12-01

Mass balance studies are important to assess the state of glaciers. Previously, numerous field investigations have been carried out in Baspa basin to measure mass balance. However, mass balance data from field are limited to a small number of glaciers and for short durations. Therefore, this study uses geodetic mass balance technique to evaluate the mass loss at decadal scale. Geodetic method involves differencing Digital Elevation Model (DEM) from different years to obtain change in glacier elevation, which will be subsequently used to evaluate mass balance. This study derives mass balance from 2000 to 2014 for 16 glaciers covering a total area of 70 Sq Km. The study uses Shuttle Radar Topography Mission (SRTM) DEM for year 2000 and DEM for year 2014 was derived from Cartosat-1 stereo pair using photogrammetric principles. A Differential Global Positioning System (DGPS) survey was conducted in Baspa basin at different elevation zones to collect Ground Control Points (GCP) with millimeters accuracy. These GCP were used to derive Cartosat DEM. Various corrections were applied before differencing the two DEMs. They were co-registered using an analytical approach to account for horizontal shift. Corrections were also applied to remove the bias due to satellite acquisition geometry. SRTM DEM was acquired in February when the study area was covered by seasonal snow, whereas, Cartosat data was acquired during the ablation season. As the season of data acquisition varies for the two DEM, we have corrected for the bias that could be caused due to seasonal snow. Snowfall data from a meteorological station in the Baspa valley and a local precipitation gradient were used to determine the seasonal snow depth. Further, corrections were applied to account for the bias due to radar penetration in SRTM DEM. Then, the elevation changes were determined by subtracting the two DEMs to estimate mass balance. The figure below shows the change in glacier elevation. These results will be validated with field estimates. This investigation, after validation, will be an important addition in understanding changes in Himalayan glaciers.

The Energy Balance Study: The Design and Baseline Results for a Longitudinal Study of Energy Balance

ERIC Educational Resources Information Center

Hand, Gregory A.; Shook, Robin P.; Paluch, Amanda E.; Baruth, Meghan; Crowley, E. Patrick; Jaggers, Jason R.; Prasad, Vivek K.; Hurley, Thomas G.; Hebert, James R.; O'Connor, Daniel P.; Archer, Edward; Burgess, Stephanie; Blair, Steven N.

2013-01-01

Purpose: The Energy Balance Study (EBS) was a comprehensive study designed to determine over a period of 12 months the associations of caloric intake and energy expenditure on changes in body weight and composition in a population of healthy men and women. Method: EBS recruited men and women aged 21 to 35 years with a body mass index between 20…

14 CFR 23.659 - Mass balance.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Mass balance. 23.659 Section 23.659 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... Surfaces § 23.659 Mass balance. The supporting structure and the attachment of concentrated mass balance...

14 CFR 23.659 - Mass balance.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Mass balance. 23.659 Section 23.659 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... Surfaces § 23.659 Mass balance. The supporting structure and the attachment of concentrated mass balance...

Study of Annual Mass Balance (2011-2013) of Rikha Samba Glacier, Hidden Valley, Mustang, Nepal

NASA Astrophysics Data System (ADS)

Gurung, S.; Bhattrai, B. C.; Kayastha, R. B.; Stumm, D.; Joshi, S.; Mool, P. K.

2016-12-01

lthough Himalayan glaciers are of particular interest interms of future water supplies, regional climate changes, and sea-level rises, little is known about them due to lack of reliable and consistent data. There is a need for monitoring these glaciers to bridge this knowledge gap and to provide field measurements necessary to calibrate and validate the results from different remote sensing operations. Therefore, glaciological observations have been carried out by the Cryosphere Monitoring Project (CMP) since September 2011 on Rikha Samba Glacier in Hidden valley, Mustang district in western Nepal in order to study its annual mass balance. This paper presents the first results of that study. There are 10 glaciers in Hidden Valley, named G1, G2, G3, up to G10. Of these, G5 is the Rikha Samba Glacier, which has the largest area (5.37 km2) in this valley and the highest and lowest altitudes (6,476 and 5,392 m a.s.l., respectively). The glacier mass balance discussed in this paper was calculated using the glaciological method and the equilibrium line altitude (ELA).The glacier showed a negative annual point mass balance along the longitudinal profile of its lower part from September 10, 2011 to October 3, 2012. Stake measurements from October 4, 2012 to September 30, 2013 indicated a negative areal average of annual mass balance -0.088±0.019 m w.e. for the whole glacier. Based on these observations, the ELA of the Rikha Samba Glacier is estimated at 5,800 m a.s.l. in 2013. This negative balance may be due to rising air temperatures in the region, which have been incrementally rising since 1980 accompanied by little or no significant increase in precipitation in that period. The negative mass balance confirms the general shrinking trend of the glacier.

Stability improvement of a four cable-driven parallel manipulator using a center of mass balance system

NASA Astrophysics Data System (ADS)

Salafian, Iman; Stewart, Blake; Newman, Matthew; Zygielbaum, Arthur I.; Terry, Benjamin

2017-04-01

A four cable-driven parallel manipulator (CDPM), consisting of sophisticated spectrometers and imagers, is under development for use in acquiring phenotypic and environmental data over an acre-sized crop field. To obtain accurate and high quality data from the instruments, the end effector must be stable during sensing. One of the factors that reduces stability is the center of mass offset of the end effector, which can cause a pendulum effect or undesired tilt angle. The purpose of this work is to develop a system and method for balancing the center of mass of a 12th-scale CDPM to minimize vibration that can cause error in the acquired data. A simple method for balancing the end effector is needed to enable end users of the CDPM to arbitrarily add and remove sensors and imagers from the end effector as their experiments may require. A Center of Mass Balancing System (CMBS) is developed in this study which consists of an adjustable system of weights and a gimbal for tilt mitigation. An electronic circuit board including an orientation sensor, wireless data communication, and load cells was designed to validate the CMBS. To measure improvements gained by the CMBS, several static and dynamic experiments are carried out. In the experiments, the dynamic vibrations due to the translational motion and static orientation were measured with and without CMBS use. The results show that the CMBS system improves the stability of the end-effector by decreasing vibration and static tilt angle.

Tuning the Stiffness Balance Using Characteristic Frequencies as a Criterion for a Superconducting Gravity Gradiometer

PubMed Central

Liu, Xikai; Ma, Dong; Chen, Liang; Liu, Xiangdong

2018-01-01

Tuning the stiffness balance is crucial to full-band common-mode rejection for a superconducting gravity gradiometer (SGG). A reliable method to do so has been proposed and experimentally tested. In the tuning scheme, the frequency response functions of the displacement of individual test mass upon common-mode accelerations were measured and thus determined a characteristic frequency for each test mass. A reduced difference in characteristic frequencies between the two test masses was utilized as the criterion for an effective tuning. Since the measurement of the characteristic frequencies does not depend on the scale factors of displacement detection, stiffness tuning can be done independently. We have tested this new method on a single-component SGG and obtained a reduction of two orders of magnitude in stiffness mismatch. PMID:29419796

Independent effects of adding weight and inertia on balance during quiet standing

PubMed Central

2012-01-01

Background Human balance during quiet standing is influenced by adding mass to the body with a backpack, with symmetrically-applied loads to the trunk, or with obesity. Adding mass to the body increases both the weight and inertia of the body, which theoretically could provide counteracting effects on body dynamics and balance. Understanding the independent effects of adding weight and inertia on balance may provide additional insight into human balance that could lead to novel advancements in balance training and rehabilitation. Therefore, the purpose of this study was to investigate the independent effects of adding weight and inertia on balance during quiet standing. Methods Sixteen normal-weight young adult participants stood as still as possible on a custom-built backboard apparatus under four experimental conditions: baseline, added inertia only, added weight only, and added inertia and weight. Results Adding inertia by itself had no measurable effect on center of pressure movement or backboard movement. Adding weight by itself increased center of pressure movement (indicated greater effort by the postural control system to stand as still as possible) and backboard movement (indicating a poorer ability of the body to stand as still as possible). Adding inertia and weight at the same time increased center of pressure movement but did not increase backboard movement compared to the baseline condition. Conclusions Adding inertia and adding weight had different effects on balance. Adding inertia by itself had no effect on balance. Adding weight by itself had a negative effect on balance. When adding inertia and weight at the same time, the added inertia appeared to lessen (but did not eliminate) the negative effect of adding weight on balance. These results improve our fundamental understanding of how added mass influences human balance. PMID:22507125

Is the difference between chemical and numerical estimates of baseflow meaningful?

NASA Astrophysics Data System (ADS)

Cartwright, Ian; Gilfedder, Ben; Hofmann, Harald

2014-05-01

Both chemical and numerical techniques are commonly used to calculate baseflow inputs to gaining rivers. In general the chemical methods yield lower estimates of baseflow than the numerical techniques. In part, this may be due to the techniques assuming two components (event water and baseflow) whereas there may also be multiple transient stores of water. Bank return waters, interflow, or waters stored on floodplains are delayed components that may be geochemically similar to the surface water from which they are derived; numerical techniques may record these components as baseflow whereas chemical mass balance studies are likely to aggregate them with the surface water component. This study compares baseflow estimates using chemical mass balance, local minimum methods, and recursive digital filters in the upper reaches of the Barwon River, southeast Australia. While more sophisticated techniques exist, these methods of estimating baseflow are readily applied with the available data and have been used widely elsewhere. During the early stages of high-discharge events, chemical mass balance overestimates groundwater inflows, probably due to flushing of saline water from wetlands and marshes, soils, or the unsaturated zone. Overall, however, estimates of baseflow from the local minimum and recursive digital filters are higher than those from chemical mass balance using Cl calculated from continuous electrical conductivity. Between 2001 and 2011, the baseflow contribution to the upper Barwon River calculated using chemical mass balance is between 12 and 25% of annual discharge. Recursive digital filters predict higher baseflow contributions of 19 to 52% of annual discharge. These estimates are similar to those from the local minimum method (16 to 45% of annual discharge). These differences most probably reflect how the different techniques characterise the transient water sources in this catchment. The local minimum and recursive digital filters aggregate much of the water from delayed sources as baseflow. However, as many of these delayed transient water stores (such as bank return flow, floodplain storage, or interflow) have Cl concentrations that are similar to surface runoff, chemical mass balance calculations aggregate them with the surface runoff component. The difference between the estimates is greatest following periods of high discharge in winter, implying that these transient stores of water feed the river for several weeks to months at that time. Cl vs. discharge variations during individual flow events also demonstrate that inflows of high-salinity older water occurs on the rising limbs of hydrographs followed by inflows of low-salinity water from the transient stores as discharge falls. The use of complementary techniques allows a better understanding of the different components of water that contribute to river flow, which is important for the management and protection of water resources.

Ice-sheet contributions to future sea-level change.

PubMed

Gregory, J M; Huybrechts, P

2006-07-15

Accurate simulation of ice-sheet surface mass balance requires higher spatial resolution than is afforded by typical atmosphere-ocean general circulation models (AOGCMs), owing, in particular, to the need to resolve the narrow and steep margins where the majority of precipitation and ablation occurs. We have developed a method for calculating mass-balance changes by combining ice-sheet average time-series from AOGCM projections for future centuries, both with information from high-resolution climate models run for short periods and with a 20km ice-sheet mass-balance model. Antarctica contributes negatively to sea level on account of increased accumulation, while Greenland contributes positively because ablation increases more rapidly. The uncertainty in the results is about 20% for Antarctica and 35% for Greenland. Changes in ice-sheet topography and dynamics are not included, but we discuss their possible effects. For an annual- and area-average warming exceeding 4.5+/-0.9K in Greenland and 3.1+/-0.8K in the global average, the net surface mass balance of the Greenland ice sheet becomes negative, in which case it is likely that the ice sheet would eventually be eliminated, raising global-average sea level by 7m.

David W. Templeton | NREL

Science.gov Websites

and algal biomass analysis methods and applications of these methods to different processes. Templeton , internally funded research project to develop microalgal compositional analysis methods that included setting methods Closing mass and component balances around pretreatment, saccharification, and fermentation unit

14 CFR 29.659 - Mass balance.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Mass balance. 29.659 Section 29.659... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction Rotors § 29.659 Mass balance. (a) The rotor... flutter at any speed up to the maximum forward speed. (b) The structural integrity of the mass balance...

14 CFR 27.659 - Mass balance.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Mass balance. 27.659 Section 27.659... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction Rotors § 27.659 Mass balance. (a) The rotors... flutter at any speed up to the maximum forward speed. (b) The structural integrity of the mass balance...

14 CFR 27.659 - Mass balance.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Mass balance. 27.659 Section 27.659... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction Rotors § 27.659 Mass balance. (a) The rotors... flutter at any speed up to the maximum forward speed. (b) The structural integrity of the mass balance...

14 CFR 29.659 - Mass balance.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Mass balance. 29.659 Section 29.659... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction Rotors § 29.659 Mass balance. (a) The rotor... flutter at any speed up to the maximum forward speed. (b) The structural integrity of the mass balance...

14 CFR 29.659 - Mass balance.

Code of Federal Regulations, 2014 CFR

2014-01-01

... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction Rotors § 29.659 Mass balance. (a) The rotor and blades must be mass balanced as necessary to— (1) Prevent excessive vibration; and (2) Prevent... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Mass balance. 29.659 Section 29.659...

14 CFR 27.659 - Mass balance.

Code of Federal Regulations, 2014 CFR

2014-01-01

... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction Rotors § 27.659 Mass balance. (a) The rotors and blades must be mass balanced as necessary to— (1) Prevent excessive vibration; and (2) Prevent... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Mass balance. 27.659 Section 27.659...

14 CFR 29.659 - Mass balance.

Code of Federal Regulations, 2012 CFR

2012-01-01

... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction Rotors § 29.659 Mass balance. (a) The rotor and blades must be mass balanced as necessary to— (1) Prevent excessive vibration; and (2) Prevent... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Mass balance. 29.659 Section 29.659...

14 CFR 27.659 - Mass balance.

Code of Federal Regulations, 2013 CFR

2013-01-01

... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction Rotors § 27.659 Mass balance. (a) The rotors and blades must be mass balanced as necessary to— (1) Prevent excessive vibration; and (2) Prevent... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Mass balance. 27.659 Section 27.659...

14 CFR 27.659 - Mass balance.

Code of Federal Regulations, 2012 CFR

2012-01-01

... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction Rotors § 27.659 Mass balance. (a) The rotors and blades must be mass balanced as necessary to— (1) Prevent excessive vibration; and (2) Prevent... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Mass balance. 27.659 Section 27.659...

14 CFR 29.659 - Mass balance.

Code of Federal Regulations, 2013 CFR

2013-01-01

... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction Rotors § 29.659 Mass balance. (a) The rotor and blades must be mass balanced as necessary to— (1) Prevent excessive vibration; and (2) Prevent... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Mass balance. 29.659 Section 29.659...

Spatial and Temporal Antarctic Ice Sheet Mass Trends, Glacio-Isostatic Adjustment, and Surface Processes from a Joint Inversion of Satellite Altimeter, Gravity, and GPS Data

NASA Technical Reports Server (NTRS)

Martin-Espanol, Alba; Zammit-Mangion, Andrew; Clarke, Peter J.; Flament, Thomas; Helm, Veit; King, Matt A.; Luthcke, Scott B.; Petrie, Elizabeth; Remy, Frederique; Schon, Nana;

Mass balancing of hollow fan blades

NASA Technical Reports Server (NTRS)

Kielb, R. E.

1986-01-01

A typical section model is used to analytically investigate the effect of mass balancing as applied to hollow, supersonic fan blades. A procedure to determine the best configuration of an internal balancing mass to provide flutter alleviation is developed. This procedure is applied to a typical supersonic shroudless fan blade which is unstable in both the solid configuration and when it is hollow with no balancing mass. The addition of an optimized balancing mass is shown to stabilize the blade at the design condition.

Progress toward Consensus Estimates of Regional Glacier Mass Balances for IPCC AR5

NASA Astrophysics Data System (ADS)

Arendt, A. A.; Gardner, A. S.; Cogley, J. G.

2011-12-01

Glaciers are potentially large contributors to rising sea level. Since the last IPCC report in 2007 (AR4), there has been a widespread increase in the use of geodetic observations from satellite and airborne platforms to complement field observations of glacier mass balance, as well as significant improvements in the global glacier inventory. Here we summarize our ongoing efforts to integrate data from multiple sources to arrive at a consensus estimate for each region, and to quantify uncertainties in those estimates. We will use examples from Alaska to illustrate methods for combining Gravity Recovery and Climate Experiment (GRACE), elevation differencing and field observations into a single time series with related uncertainty estimates. We will pay particular attention to reconciling discrepancies between GRACE estimates from multiple processing centers. We will also investigate the extent to which improvements in the glacier inventory affect the accuracy of our regional mass balances.

Purity assessment of organic calibration standards using a combination of quantitative NMR and mass balance.

PubMed

Davies, Stephen R; Jones, Kai; Goldys, Anna; Alamgir, Mahuiddin; Chan, Benjamin K H; Elgindy, Cecile; Mitchell, Peter S R; Tarrant, Gregory J; Krishnaswami, Maya R; Luo, Yawen; Moawad, Michael; Lawes, Douglas; Hook, James M

2015-04-01

Quantitative NMR spectroscopy (qNMR) has been examined for purity assessment using a range of organic calibration standards of varying structural complexities, certified using the traditional mass balance approach. Demonstrated equivalence between the two independent purity values confirmed the accuracy of qNMR and highlighted the benefit of using both methods in tandem to minimise the potential for hidden bias, thereby conferring greater confidence in the overall purity assessment. A comprehensive approach to purity assessment is detailed, utilising, where appropriate, multiple peaks in the qNMR spectrum, chosen on the basis of scientific reason and statistical analysis. Two examples are presented in which differences between the purity assignment by qNMR and mass balance are addressed in different ways depending on the requirement of the end user, affording fit-for-purpose calibration standards in a cost-effective manner.

Review and Extension of CO2-Based Methods to Determine Ventilation Rates with Application to School Classrooms

PubMed Central

Batterman, Stuart

2017-01-01

The ventilation rate (VR) is a key parameter affecting indoor environmental quality (IEQ) and the energy consumption of buildings. This paper reviews the use of CO2 as a “natural” tracer gas for estimating VRs, focusing on applications in school classrooms. It provides details and guidance for the steady-state, build-up, decay and transient mass balance methods. An extension to the build-up method and an analysis of the post-exercise recovery period that can increase CO2 generation rates are presented. Measurements in four mechanically-ventilated school buildings demonstrate the methods and highlight issues affecting their applicability. VRs during the school day fell below recommended minimum levels, and VRs during evening and early morning were on the order of 0.1 h−1, reflecting shutdown of the ventilation systems. The transient mass balance method was the most flexible and advantageous method given the low air change rates and dynamic occupancy patterns observed in the classrooms. While the extension to the build-up method improved stability and consistency, the accuracy of this and the steady-state method may be limited. Decay-based methods did not reflect the VR during the school day due to heating, ventilation and air conditioning (HVAC) system shutdown. Since the number of occupants in classrooms changes over the day, the VR expressed on a per person basis (e.g., L·s−1·person−1) depends on the occupancy metric. If occupancy measurements can be obtained, then the transient mass balance method likely will provide the most consistent and accurate results among the CO2-based methods. Improved VR measurements can benefit many applications, including research examining the linkage between ventilation and health. PMID:28165398

Review and Extension of CO₂-Based Methods to Determine Ventilation Rates with Application to School Classrooms.

PubMed

Batterman, Stuart

2017-02-04

The ventilation rate (VR) is a key parameter affecting indoor environmental quality (IEQ) and the energy consumption of buildings. This paper reviews the use of CO₂ as a "natural" tracer gas for estimating VRs, focusing on applications in school classrooms. It provides details and guidance for the steady-state, build-up, decay and transient mass balance methods. An extension to the build-up method and an analysis of the post-exercise recovery period that can increase CO₂ generation rates are presented. Measurements in four mechanically-ventilated school buildings demonstrate the methods and highlight issues affecting their applicability. VRs during the school day fell below recommended minimum levels, and VRs during evening and early morning were on the order of 0.1 h -1 , reflecting shutdown of the ventilation systems. The transient mass balance method was the most flexible and advantageous method given the low air change rates and dynamic occupancy patterns observed in the classrooms. While the extension to the build-up method improved stability and consistency, the accuracy of this and the steady-state method may be limited. Decay-based methods did not reflect the VR during the school day due to heating, ventilation and air conditioning (HVAC) system shutdown. Since the number of occupants in classrooms changes over the day, the VR expressed on a per person basis (e.g., L·s -1 ·person -1 ) depends on the occupancy metric. If occupancy measurements can be obtained, then the transient mass balance method likely will provide the most consistent and accurate results among the CO₂-based methods. Improved VR measurements can benefit many applications, including research examining the linkage between ventilation and health.

[Energy and mass exchange and the productivity of the main ecosystems of Siberia (from eddy covariance measurements). 1. Heat balance structure in the vegetation season].

PubMed

Chebakova, N M; Vygodskaia, N N; Arnet, A; Belelli Markezini, L; Kolle, O; Kurbatova, Iu A; Parfenova, E I; Valentini, R; Vaganov, E A; Shul'tse, E D

2013-01-01

Direct measurements of heat balance (turbulent heat transfer and evaporation heat consumption) by the method of turbulent pulsations in 1998-2000 and 2002-2004 were used to obtain information on the daily, seasonal, and annual dynamics of energy fluxes and mass transfer between the atmosphere and the typical ecosystems of Siberia (middle-taiga pine forest and raised bog, true four-grass steppe, with the use of data for typical tundra) along the Yenisei meridian (90 degrees E).

DEVELOPMENT OF A CONTAMINANT TRANSPORT AND FATE MASS BALANCE CALIBRATION MODEL FOR LAKE MICHIGAN MASS BALANCE PROJECT (LMMBP)

EPA Science Inventory

Lake Michigan Mass Balance Project (LMMBP) was initiated to directly support the development of a lakewide management plan (LaMP) for Lake Michigan. A mass balance modeling approach is proposed for the project to addrss the realtionship between sources of toxic chemicals and thei...

Remote Sensing of Cryosphere: Estimation of Mass Balance Change in Himalayan Glaciers

NASA Astrophysics Data System (ADS)

Ambinakudige, Shrinidhi; Joshi, Kabindra

2012-07-01

Glacial changes are an important indicator of climate change. Our understanding mass balance change in Himalayan glaciers is limited. This study estimates mass balance of some major glaciers in the Sagarmatha National Park (SNP) in Nepal using remote sensing applications. Remote sensing technique to measure mass balance of glaciers is an important methodological advance in the highly rugged Himalayan terrain. This study uses ASTER VNIR, 3N (nadir view) and 3B (backward view) bands to generate Digital Elevation Models (DEMs) for the SNP area for the years 2002, 2003, 2004 and 2005. Glacier boundaries were delineated using combination of boundaries available in the Global land ice measurement (GLIMS) database and various band ratios derived from ASTER images. Elevation differences, glacial area, and ice densities were used to estimate the change in mass balance. The results indicated that the rate of glacier mass balance change was not uniform across glaciers. While there was a decrease in mass balance of some glaciers, some showed increase. This paper discusses how each glacier in the SNP area varied in its annual mass balance measurement during the study period.

Dynamic analysis of lunar lander during soft landing using explicit finite element method

NASA Astrophysics Data System (ADS)

Zheng, Guang; Nie, Hong; Chen, Jinbao; Chen, Chuanzhi; Lee, Heow Pueh

2018-07-01

In this paper, the soft-landing analysis of a lunar lander spacecraft under three loading case was carried out in ABAQUS, using the Explicit Finite Element method. To ensure the simulation result's accuracy and reliability, the energy and mass balance criteria of the model was presented along with the theory and calculation method, and the results were benchmarked with other software (LS-DYNA) to get a validated model. The results from three loading case showed that the energy and mass of the models were conserved during soft landing, which satisfies the energy and mass balance criteria. The overloading response, structure steady state, and the crushing stroke of this lunar lander all met the design requirements of the lunar lander. The buffer energy-absorbing properties in this model have a good energy-absorbing capability, in which up to 84% of the initial energy could be dissipated. The design parameters of the model could guide the design of future manned landers or larger lunar landers.

Using chloride and chlorine-36 as soil-water tracers to estimate deep percolation at selected locations on the U.S. Department of Energy Hanford site, Washington

USGS Publications Warehouse

Prych, Edmund A.

1995-01-01

Long-term average deep-percolation rates of water from precipitation on the U.S. Department of Energy Hanford Site in semiarid south-central Washington, as estimated by a chloride mass-balance method, range from 0.008 to 0.30 mm/yr (millimeters per year) at nine locations covered by a variety of fine-grain soils and vegetated with sagebrush and other deep-rooted plants plus sparse shallow-rooted grasses. Deep-percolation rates estimated using a chlorine-36 bomb-pulse method at three of the nine locations range from 2.1 to 3.4 mm/yr. Because the mass-balance method may underestimate percolation rates and the bomb-pulse method probably overestimates percolation rates, estimates by the two methods probably bracket actual rates. These estimates, as well as estimates by previous investigators who used different methods, are a small fraction of mean annual precipitation, which ranges from about 160 to 210 mm/yr at the different test locations. Estimates by the mass-balance method at four locations in an area that is vegetated only with sparse shallow-rooted grasses range from 0.39 to 2.0 mm/yr. Chlorine-36 data at one location in this area were sufficient only to determine that the upper limit of deep percolation is more than 5.1 mm/yr. Although estimates for locations in this area are larger than the estimates for locations with deep-rooted plants, they are at the lower end of the range of estimates for this area made by previous investigators.

Carbon source/sink function of a subtropical, eutrophic lake determined from an overall mass balance and a gas exchange and carbon burial balance.

PubMed

Yang, Hong; Xing, Yangping; Xie, Ping; Ni, Leyi; Rong, Kewen

2008-02-01

Although studies on carbon burial in lake sediments have shown that lakes are disproportionately important carbon sinks, many studies on gaseous carbon exchange across the water-air interface have demonstrated that lakes are supersaturated with CO(2) and CH(4) causing a net release of CO(2) and CH(4) to the atmosphere. In order to more accurately estimate the net carbon source/sink function of lake ecosystems, a more comprehensive carbon budget is needed, especially for gaseous carbon exchange across the water-air interface. Using two methods, overall mass balance and gas exchange and carbon burial balance, we assessed the carbon source/sink function of Lake Donghu, a subtropical, eutrophic lake, from April 2003 to March 2004. With the overall mass balance calculations, total carbon input was 14 905 t, total carbon output was 4950 t, and net carbon budget was +9955 t, suggesting that Lake Donghu was a great carbon sink. For the gas exchange and carbon burial balance, gaseous carbon (CO(2) and CH(4)) emission across the water-air interface totaled 752 t while carbon burial in the lake sediment was 9477 t. The ratio of carbon emission into the atmosphere to carbon burial into the sediment was only 0.08. This low ratio indicates that Lake Donghu is a great carbon sink. Results showed good agreement between the two methods with both showing Lake Donghu to be a great carbon sink. This results from the high primary production of Lake Donghu, substantive allochthonous carbon inputs and intensive anthropogenic activity. Gaseous carbon emission accounted for about 15% of the total carbon output, indicating that the total output would be underestimated without including gaseous carbon exchange.

Calculation methods to perform mass balances of micropollutants in sewage treatment plants. application to pharmaceutical and personal care products (PPCPs).

PubMed

Carballa, Marta; Omil, Francisco; Lema, Juan M

2007-02-01

Two different methods are proposed to perform the mass balance calculations of micropollutants in sewage treatment plants (STPs). The first method uses the measured data in both liquid and sludge phase and the second one uses the solid-water distribution coefficient (Kd) to calculate the concentrations in the sludge from those measured in the liquid phase. The proposed methodologies facilitate the identification of the main mechanisms involved in the elimination of micropollutants. Both methods are applied for determining mass balances of selected pharmaceutical and personal care products (PPCPs) and their results are discussed. In that way, the fate of 2 musks (galaxolide and tonalide), 3 pharmaceuticals (ibuprofen, naproxen, and sulfamethoxazole), and 2 natural estrogens (estrone and 17beta-estradiol) has been investigated along the different water and sludge treatment units of a STP. Ibuprofen, naproxen, and sulfamethoxazole are biologically degraded in the aeration tank (50-70%), while musks are equally sorbed to the sludge and degraded. In contrast, estrogens are not removed in the STP studied. About 40% of the initial load of pharmaceuticals passes through the plant unaltered, with the fraction associated to sludge lower than 0.5%. In contrast, between 20 and 40% of the initial load of musks leaves the plant associated to solids, with less than 10% present in the final effluent. The results obtained show that the conclusions concerning the efficiency of micropollutants removal in a particular STP may be seriously affected by the calculation method used.

Modelling distributed mountain glacier volumes: A sensitivity study in the Austrian Alps

NASA Astrophysics Data System (ADS)

Helfricht, Kay; Huss, Matthias; Fischer, Andrea; Otto, Jan Christoph

2017-04-01

Knowledge about the spatial ice thickness distribution in glacier covered mountain regions and the elevation of the bedrock underneath the glaciers yields the basis for numerous applications in geoscience. Applications include the modelling of glacier dynamics, natural risk analyses and studies on mountain hydrology. Especially in recent times of accelerating and unprecedented changes of glacier extents, the remaining ice volume is of interest regarding future glacier and sea level scenarios. Subglacial depressions concern because of their hazard potential in case of sudden releases of debris or water. A number of approaches with different level of complexity have been developed in the past years to infer glacier ice thickness from surface characteristics. Within the FUTURELAKES project, the ice thickness estimation method presented by Huss and Farinotti (2012) was applied to all glaciers in the Austrian Alps based on glacier extents and surface topography corresponding to the three Austrian glacier inventories (1969 - 1997 - 2006) with the aim to predict size and location of future proglacial lakes. The availability of measured ice thickness data and a time series of glacier inventories of Austrian glaciers, allowed carrying out a sensitivity study of the key parameter, the apparent mass balance gradient. First, the parameters controlling the apparent mass balance gradient of 58 glaciers where calibrated glacier-wise with the aim to minimize mean deviations and mean absolute deviations to measured ice thickness. The results were analysed with respect to changes of the mass balance gradient with time. Secondly, we compared the observed to modelled ice thickness changes. For doing so, glacier-wise as well as regional means of mass balance gradients have been used. The results indicate that the initial values for the apparent mass balance gradient have to be adapted to the changing conditions within the four decades covered by the glacier inventories. The gradients flatten from the first to last inventory. This is consistent with the decreasing deviation between glaciological and geodetical glacier mass balance when a period with negative mass balances results in decreasing ice dynamics. The comparison of mean ice thickness changes between the Inventories reveals the effect of changes in glacier mass transport in addition to changes in glacier area and topography. 93% of the mean observed ice thickness change could be reproduced using the glacier-wise optimized mass balance gradients. More than 85% of mean ice thickness change was calculated from modelled ice thickness distributions with inventory mean optimized mass balance gradients. The ratio decreases to 60% the same parameters for all three glacier inventories and can be attributed to changes in glacier extent. Thus, the actual glacier mass turnover has to be considered to model glacier volumes based on glacier topography more realistically. Huss, M., and D. Farinotti (2012), Distributed ice thickness and volume of all glaciers around the globe, J. Geophys. Res., 117, F04010, doi:10.1029/2012JF002523.

Quantifying ice loss in the eastern Himalayas since 1974 using declassified spy satellite imagery

NASA Astrophysics Data System (ADS)

Maurer, Joshua M.; Rupper, Summer B.; Schaefer, Joerg M.

2016-09-01

Himalayan glaciers are important natural resources and climate indicators for densely populated regions in Asia. Remote sensing methods are vital for evaluating glacier response to changing climate over the vast and rugged Himalayan region, yet many platforms capable of glacier mass balance quantification are somewhat temporally limited due to typical glacier response times. We here rely on declassified spy satellite imagery and ASTER data to quantify surface lowering, ice volume change, and geodetic mass balance during 1974-2006 for glaciers in the eastern Himalayas, centered on the Bhutan-China border. The wide range of glacier types allows for the first mass balance comparison between clean, debris, and lake-terminating (calving) glaciers in the region. Measured glaciers show significant ice loss, with an estimated mean annual geodetic mass balance of -0.13 ± 0.06 m w.e. yr-1 (meters of water equivalent per year) for 10 clean-ice glaciers, -0.19 ± 0.11 m w.e. yr-1 for 5 debris-covered glaciers, -0.28 ± 0.10 m w.e. yr-1 for 6 calving glaciers, and -0.17 ± 0.05 m w.e. yr-1 for all glaciers combined. Contrasting hypsometries along with melt pond, ice cliff, and englacial conduit mechanisms result in statistically similar mass balance values for both clean-ice and debris-covered glacier groups. Calving glaciers comprise 18 % (66 km2) of the glacierized area yet have contributed 30 % (-0.7 km3) to the total ice volume loss, highlighting the growing relevance of proglacial lake formation and associated calving for the future ice mass budget of the Himalayas as the number and size of glacial lakes increase.

An eleven-year record of mass balance of Brewster Glacier, New Zealand, determined using a geostatistical approach

NASA Astrophysics Data System (ADS)

Cullen, N. J.; Anderson, B.; Sirguey, P. J.; Stumm, D.; Mackintosh, A.; Conway, J. P.; Horgan, H. J.; Dadic, R.; Fitzsimons, S.; Lorrey, A.

2016-12-01

Recognizing the scarcity of glacier mass balance data in the Southern Hemisphere, a mass balance measurement program was started at Brewster Glacier in 2004. Evolution of the measurement regime over the 11 years of data recorded means there are differences in the spatial density of data obtained. To ensure the temporal integrity of the dataset a new, geostatistical approach has been developed to calculate mass balance. Spatial co-variance between elevation and snow depth has enabled a digital elevation model to be used in a co-kriging approach to develop a snow depth index (SDI). By capturing the observed spatial variability in snow depth, the SDI is a more reliable predictor than elevation and is used to adjust each year of measurements consistently despite variability in sampling spatial density. The SDI also resolves the spatial structure of summer balance better than elevation. Co-kriging is used again to spatially interpolate a derived mean summer balance index using SDI as a co-variate, which yields a spatial predictor for summer balance. A similar approach is also used to create a predictor for annual balance, which allows us to revisit years where summer balance was not obtained. The average glacier-wide surface winter, summer and annual mass balances over the period 2005-2015 are 2484, -2586, and -102 mm w.e., respectively, with changes in summer balance explaining most of the variability in annual balance. On the whole, there is good agreement between our ELA and AAR values and those derived from the end-of-summer snowline (EOSS) program, though discrepancies in some years cannot be fully accounted for. A mass balance map of Brewster Glacier in an equilibrium state, which by definition has a glacier-wide mass balance equal to zero (a balanced-budget), is used to calculate values of ELA (1923 ±25 m) and AAR (0.40) representative of the observational period. The relationships between mass balance and ELA/AAR are explored, demonstrating they are mostly linear. On average, the mass balance gradients are found to be equal to 14.5 and 7.4 mm we m-1 in the ablation and accumulation zones, respectively. However, there is considerable variability in the gradients from year to year, as well as variability between different elevation bands. The largest variability in the mass balance gradient is observed in the ablation zone.

The research of hourglass worm dynamic balancing simulation based on SolidWorks motion

NASA Astrophysics Data System (ADS)

Wang, Zhuangzhuang; Yang, Jie; Liu, Pingyi; Zhao, Junpeng

2018-02-01

Hourglass worm is extensively used in industry due to its characteristic of heavy-load and a large reduction ratio. Varying sizes of unbalanced mass distribution appeared in the design of a single head worm. With machines developing towards higher speed and precision, the vibration and shock caused by the unbalanced mass distribution of rotating parts must be considered. Therefore, the balance grade of these parts must meet higher requirements. A method based on theoretical analysis and SolidWorks motion software simulation is presented in this paper; the virtual dynamic balance simulation test of the hourglass worm was carried out during the design of the product, so as to ensure that the hourglass worm meet the requirements of dynamic balance in the design process. This can effectively support the structural design of the hourglass worm and provide a way of thinking and designing the same type of products.

Climate, not atmospheric deposition, drives the biogeochemical mass-balance of a mountain watershed

USGS Publications Warehouse

Baron, Jill S.; Heath, Jared

2014-01-01

Watershed mass-balance methods are valuable tools for demonstrating impacts to water quality from atmospheric deposition and chemical weathering. Owen Bricker, a pioneer of the mass-balance method, began applying mass-balance modeling to small watersheds in the late 1960s and dedicated his career to expanding the literature and knowledge of complex watershed processes. We evaluated long-term trends in surface-water chemistry in the Loch Vale watershed, a 660-ha. alpine/subalpine catchment located in Rocky Mountain National Park, CO, USA. Many changes in surface-water chemistry correlated with multiple drivers, including summer or monthly temperature, snow water equivalent, and the runoff-to-precipitation ratio. Atmospheric deposition was not a significant causal agent for surface-water chemistry trends. We observed statistically significant increases in both concentrations and fluxes of weathering products including cations, SiO2, SO4 2−, and ANC, and in inorganic N, with inorganic N being primarily of atmospheric origin. These changes are evident in the individual months June, July, and August, and also in the combined June, July, and August summer season. Increasingly warm summer temperatures are melting what was once permanent ice and this may release elements entrained in the ice, stimulate chemical weathering with enhanced moisture availability, and stimulate microbial nitrification. Weathering rates may also be enhanced by sustained water availability in high snowpack years. Rapid change in the flux of weathering products and inorganic N is the direct and indirect result of a changing climate from warming temperatures and thawing cryosphere.

[Measurement and estimation methods and research progress of snow evaporation in forests].

PubMed

Li, Hui-Dong; Guan, De-Xin; Jin, Chang-Jie; Wang, An-Zhi; Yuan, Feng-Hui; Wu, Jia-Bing

2013-12-01

Accurate measurement and estimation of snow evaporation (sublimation) in forests is one of the important issues to the understanding of snow surface energy and water balance, and it is also an essential part of regional hydrological and climate models. This paper summarized the measurement and estimation methods of snow evaporation in forests, and made a comprehensive applicability evaluation, including mass-balance methods (snow water equivalent method, comparative measurements of snowfall and through-snowfall, snow evaporation pan, lysimeter, weighing of cut tree, weighing interception on crown, and gamma-ray attenuation technique) and micrometeorological methods (Bowen-ratio energy-balance method, Penman combination equation, aerodynamics method, surface temperature technique and eddy covariance method). Also this paper reviewed the progress of snow evaporation in different forests and its influencal factors. At last, combining the deficiency of past research, an outlook for snow evaporation rearch in forests was presented, hoping to provide a reference for related research in the future.

A January angular momentum balance in the OSU two-level atmospheric general circulation model

NASA Technical Reports Server (NTRS)

Kim, J.-W.; Grady, W.

1982-01-01

The present investigation is concerned with an analysis of the atmospheric angular momentum balance, based on the simulation data of the Oregon State University two-level atmospheric general circulation model (AGCM). An attempt is also made to gain an understanding of the involved processes. Preliminary results on the angular momentum and mass balance in the AGCM are shown. The basic equations are examined, and questions of turbulent momentum transfer are investigated. The methods of analysis are discussed, taking into account time-averaged balance equations, time and longitude-averaged balance equations, mean meridional circulation, the mean meridional balance of relative angular momentum, and standing and transient components of motion.

Isotopic composition of atmospheric moisture from pan water evaporation measurements.

PubMed

Devi, Pooja; Jain, Ashok Kumar; Rao, M Someshwer; Kumar, Bhishm

2015-01-01

A continuous and reliable time series data of the stable isotopic composition of atmospheric moisture is an important requirement for the wider applicability of isotope mass balance methods in atmospheric and water balance studies. This requires routine sampling of atmospheric moisture by an appropriate technique and analysis of moisture for its isotopic composition. We have, therefore, used a much simpler method based on an isotope mass balance approach to derive the isotopic composition of atmospheric moisture using a class-A drying evaporation pan. We have carried out the study by collecting water samples from a class-A drying evaporation pan and also by collecting atmospheric moisture using the cryogenic trap method at the National Institute of Hydrology, Roorkee, India, during a pre-monsoon period. We compared the isotopic composition of atmospheric moisture obtained by using the class-A drying evaporation pan method with the cryogenic trap method. The results obtained from the evaporation pan water compare well with the cryogenic based method. Thus, the study establishes a cost-effective means of maintaining time series data of the isotopic composition of atmospheric moisture at meteorological observatories. The conclusions drawn in the present study are based on experiments conducted at Roorkee, India, and may be examined at other regions for its general applicability.

Remote Sensing based modelling of Annual Surface Mass Balances of Chhota Shigiri Glacier, Western Himalayas, India

NASA Astrophysics Data System (ADS)

Chandrasekharan, Anita; Ramsankaran, Raaj

2017-04-01

The current study aims at modelling glacier mass balances over Chhota Shigiri glacier (32.28o N; 77.58° E) in Himachal Pradesh, India using the Equilibrium Line Altitude (ELA) gradient approach proposed by Rabatel et al. (2005). The model requires yearly ELA, average mass balance and mass balance gradient to estimate annual mass balance of a glacier which can be obtained either through field measurements or remote sensing observations. However, in view of the general scenario of lack of field data for Himalayan glaciers, in this study the model has been applied only using the inputs derived through multi-temporal satellite remote sensing observations thus eliminating the need for any field measurements. Preliminary analysis show that the obtained results are comparable with the observed field mass balance. The results also demonstrate that this approach with remote sensing inputs has potential to be used for glacier mass balance estimations provided good quality multi-temporal remote sensing dataset are available.

Contrasted Glacier Mass Wastage Between the Southern and the Inner Part of Everest Region Revealed from In-Situ Measurements since 2007.

NASA Astrophysics Data System (ADS)

Sherpa, S. F.; Wagnon, P.; Brun, F.; Berthier, E.; Vincent, C.; Lejeune, Y.; Arnaud, Y.; Kayastha, R. B.

2016-12-01

Three debris-free glaciers of various areas have been monitored for the last 5 to 8 years in Everest region (Central Himalaya, Nepal) and their annual glacier-wide mass balances (Ba) obtained from the glaciological method strongly differ. Mera Glacier (5.1 km2 in 2012) is located in the southern part of the region and has been in steady state over the last 5 to 8 years, whereas Pokalde (0.1 km2 in 2011) and Changri Nup glaciers (0.92 km2 in 2013), approximately 30 km farther north in the drier inner part of the range, have been losing mass rapidly with a Ba of -0.69 ± 0.28 m w.e. a-1 (2009-15) and -1.24 ± 0.27 m w.e. a-1 (2010-15), respectively. Changri Nup specific mass balance has been confirmed by the geodetic method using SPOT5 and Pléiades images from 2009, 2013 and 2015, but the validation is still incomplete because part of the avalanche-fed areas are not taken into account, which may result in a slight bias toward negative mass balances. A qualitative comparison between annual glacier-wide mass balances and annual or seasonal meteorological variables acquired at the elevation of glaciers suggests that these glaciers are sensitive to precipitation and to the incoming radiative energy fluxes. Occasional very severe cyclonic storms originating in the Bay of Bengal can reach the highlands of Nepal triggering huge snow falls, like Typhoon Phailin responsible for a +0.33 m w.e. increase in 2012-13 Ba of Mera Glacier in 2 days only (13-15 October 2013). This contrasted mass balance pattern over rather short distances can be explained by two facts. On the one hand, it is related to the low elevation of Pokalde and Changri Nup glaciers, both culminating at 5690 m a.s.l., an altitude frequently almost reached by the ELA. On the other hand, we observe a strong south-north horizontal gradient of precipitation (steeper than -21 mm km-1 corresponding to -2% km-1). We suspect that glaciers located in the inner and leeward part of the range, submitted to arid conditions, are less balanced with the present climate than glaciers located in frontal position relatively to the monsoon influx, on the windward side of the range and in turn receiving large amounts of precipitation.

Mass-based design and optimization of wave rotors for gas turbine engine enhancement

NASA Astrophysics Data System (ADS)

Chan, S.; Liu, H.

2017-03-01

An analytic method aiming at mass properties was developed for the preliminary design and optimization of wave rotors. In the present method, we introduce the mass balance principle into the design and thus can predict and optimize the mass qualities as well as the performance of wave rotors. A dedicated least-square method with artificial weighting coefficients was developed to solve the over-constrained system in the mass-based design. This method and the adoption of the coefficients were validated by numerical simulation. Moreover, the problem of fresh air exhaustion (FAE) was put forward and analyzed, and exhaust gas recirculation (EGR) was investigated. Parameter analyses and optimization elucidated which designs would not only achieve the best performance, but also operate with minimum EGR and no FAE.

Considerations affecting the additional weight required in mass balance of ailerons

NASA Technical Reports Server (NTRS)

Diehl, W S

1937-01-01

This paper is essentially a consideration of mass balance of ailerons from a preliminary design standpoint, in which the extra weight of the mass counterbalance is the most important phase of the problem. Equations are developed for the required balance weight for a simple aileron and this weight is correlated with the mass-balance coefficient. It is concluded the location of the c.g. of the basic aileron is of paramount importance and that complete mass balance imposes no great weight penalty if the aileron is designed to have its c.g. inherently near to the hinge axis.

Spatial and temporal Antarctic Ice Sheet mass trends, glacio-isostatic adjustment, and surface processes from a joint inversion of satellite altimeter, gravity, and GPS data.

PubMed

Martín-Español, Alba; Zammit-Mangion, Andrew; Clarke, Peter J; Flament, Thomas; Helm, Veit; King, Matt A; Luthcke, Scott B; Petrie, Elizabeth; Rémy, Frederique; Schön, Nana; Wouters, Bert; Bamber, Jonathan L

2016-02-01

We present spatiotemporal mass balance trends for the Antarctic Ice Sheet from a statistical inversion of satellite altimetry, gravimetry, and elastic-corrected GPS data for the period 2003-2013. Our method simultaneously determines annual trends in ice dynamics, surface mass balance anomalies, and a time-invariant solution for glacio-isostatic adjustment while remaining largely independent of forward models. We establish that over the period 2003-2013, Antarctica has been losing mass at a rate of -84 ± 22 Gt yr -1 , with a sustained negative mean trend of dynamic imbalance of -111 ± 13 Gt yr -1 . West Antarctica is the largest contributor with -112 ± 10 Gt yr -1 , mainly triggered by high thinning rates of glaciers draining into the Amundsen Sea Embayment. The Antarctic Peninsula has experienced a dramatic increase in mass loss in the last decade, with a mean rate of -28 ± 7 Gt yr -1 and significantly higher values for the most recent years following the destabilization of the Southern Antarctic Peninsula around 2010. The total mass loss is partly compensated by a significant mass gain of 56 ± 18 Gt yr -1 in East Antarctica due to a positive trend of surface mass balance anomalies.

Comparative glacio-climatological analysis of mass balance variability along the geographical margin of Europe

NASA Astrophysics Data System (ADS)

Lehoczky, Annamária; Kern, Zoltán; Pongrácz, Rita

2014-05-01

Glacio-climatological studies recognise glacier mass balance changes as high-confident climate indicators. The climatic sensitivity of a glacier does not simply depend on regional climate variability but also influenced via large- and mesoscale atmospheric circulation patterns. This study focuses on recent changes in the mass balance using records from three border regions of Europe, and investigates the relationships between the seasonal mass balance components, regional climatic conditions, and distant atmospheric forcing. Since glaciers in different macro-climatological conditions (i.e., mid-latitudes or high-latitudes, dry-continental or maritime regions) may present strongly diverse mass balance characteristics, the three analysed regions were selected from different glacierised macroregions (using the database of the World Glacier Monitoring Service). These regions belong to the Caucasus Mountains (Central Europe macroregion), the Polar Ural (Northern Asia macroregion), and Svalbard (Arctic Islands macroregion). The analysis focuses on winter, summer, and annual mass balance series of eight glaciers. The climatic variables (atmospheric pressure, air temperature, precipitation) and indices of teleconnection patterns (e.g., North Atlantic Oscillation, Pacific Decadal Oscillation) are used from the gridded databases of the University of East Anglia, Climatic Research Unit and the National Oceanic and Atmospheric Administration, National Center for Environmental Prediction. However, the period and length of available mass balance data in the selected regions vary greatly (the first full record is in 1958, Polar Ural; the last is in 2010, Caucasus Mountains), a comparative analysis can be carried out for the period of 1968-1981. Since glaciers from different regions respond to large- and mesoscale climatic forcings differently, and because the mass balance of glaciers within a region often co-vary, our specific objectives are (i) to examine the variability and the integrative climatic signal in the averaged mass balance records of the selected regions; (ii) to analyse the possible coupling between the mass balance and climatic variables, including the dominant patterns of Northern Hemisphere climate variability; and (iii) to compare the main characteristics of the three regions. Furthermore, (iv) a short discussion is given considering the significant decreasing trend of the cumulative annual mass balances in every region under the detected climatic changes in the second half of the 20th century. Preliminary results suggest that the strongest teleconnection links could be between winter mass balance and winter NAO for the Polar Ural (r=0.46, p<0.05), and between annual mass balance and PDO for Svalbard (r=-0.43, p<0.05). Neither seasonal, nor annual mass balance records showed significant correlation with any of the examined circulation indices for the Caucasus.

Using chemical benchmarking to determine the persistence of chemicals in a Swedish lake.

PubMed

Zou, Hongyan; Radke, Michael; Kierkegaard, Amelie; MacLeod, Matthew; McLachlan, Michael S

2015-02-03

It is challenging to measure the persistence of chemicals under field conditions. In this work, two approaches for measuring persistence in the field were compared: the chemical mass balance approach, and a novel chemical benchmarking approach. Ten pharmaceuticals, an X-ray contrast agent, and an artificial sweetener were studied in a Swedish lake. Acesulfame K was selected as a benchmark to quantify persistence using the chemical benchmarking approach. The 95% confidence intervals of the half-life for transformation in the lake system ranged from 780-5700 days for carbamazepine to <1-2 days for ketoprofen. The persistence estimates obtained using the benchmarking approach agreed well with those from the mass balance approach (1-21% difference), indicating that chemical benchmarking can be a valid and useful method to measure the persistence of chemicals under field conditions. Compared to the mass balance approach, the benchmarking approach partially or completely eliminates the need to quantify mass flow of chemicals, so it is particularly advantageous when the quantification of mass flow of chemicals is difficult. Furthermore, the benchmarking approach allows for ready comparison and ranking of the persistence of different chemicals.

Surface mass balance model evaluation from satellite and airborne lidar mapping

NASA Astrophysics Data System (ADS)

Sutterley, T. C.; Velicogna, I.; Fettweis, X.; van den Broeke, M. R.

2016-12-01

We present estimates of Greenland Ice Sheet (GrIS) surface elevation change from a novel combination of satellite and airborne laser altimetry measurements. Our method combines measurements from the Airborne Topographic Mapper (ATM), the Land, Vegetation and Ice Sensor (LVIS) and ICESat-1 to generate elevation change rates at high spatial resolution. This method allows to extend the records of each instrument, increases the overall spatial coverage compared to a single instrument, and produces high-quality, coherent maps of surface elevation change. In addition by combining the lidar datasets, we are able to investigate seasonal and interannual surface elevation change for years where Spring and Fall Operation IceBridge campaigns are available. We validate our method by comparing with the standard NSIDC elevation change product calculated using overlapping Level-1B ATM data. We use the altimetry-derived mass changes to evaluate the uncertainty in surface mass balance, particularly in the runoff component, from two Regional Climate Models (RCM's), the Regional Atmospheric Climate Model (RACMO) and the Modéle Atmosphérique Régional (MAR), and one Global Climate Model (GCM), MERRA2/GEOS-5. We investigate locations with low ice sheet surface velocities that are within the estimated ablation zones of each regional climate model. We find that the surface mass balance outputs from RACMO and MAR show good correspondence with mass changes derived from surface elevation changes over long periods. At two sites in Northeast Greenland (NEGIS), the MAR model has better correspondence with the altimetry estimate. We find that the differences at these locations are primarily due to the characterization of meltwater refreeze within the ice sheet.

Opportunities and Challenges in Enhancing Value of Annual Glacier Mass Balance Monitoring Examples from Western North America

NASA Astrophysics Data System (ADS)

Pelto, M. S.

2017-12-01

Alpine glacier mass balance is the most accurate indicator of glacier response to climate and with retreat of alpine glaciers is one of the clearest signals of global climate change. Completion of long term, representative and homogenous mass balance field measurement of mass balance, compiled by WGMS, is a key climate data record. To ensure a monitoring program remains vital and funded local collaboration and connecting the research to local societal impacts is crucial. Working with local partners in collecting and providing the right data is critical whether their interest is in hydropower, irrigation, municipal supply, hazard reduction and/or aquatic ecosystems. The expansion of remote sensing and modeling capability provides both a challenge to continued relevance and an opportunity for field mass balance programs to expand relevance. In modelling studies of both glacier mass balance and glacier runoff transient balance data has equivalent value with annual balance data, for both calibration runs and as an input variable. This increases the utility of mid-season field observations. Remote sensing provides repeat imagery that often identifies the AAR and transient snowline of a glacier. For runoff assessment understanding the specific percent of glacier surface area that is glacier ice, older firn, and retained snowpack from the previous winter at frequent intervals during the melt season is vital since each region has a different melt factor. A denser field observation network combined with this imagery can provide additional point balance values of ablation that complement the mass balance record. Periodic measurement of mass balance at a denser network using GPR, LIDAR, TLS or probing is required to better understand long term point balance locations and is important at end of the melt season not just beginning, and has value mid-season for modelling. Applications of each of utility of field mass balance observations will be illustrated.

Which Propensity Score Method Best Reduces Confounder Imbalance? An Example From a Retrospective Evaluation of a Childhood Obesity Intervention.

PubMed

Schroeder, Krista; Jia, Haomiao; Smaldone, Arlene

Propensity score (PS) methods are increasingly being employed by researchers to reduce bias arising from confounder imbalance when using observational data to examine intervention effects. The purpose of this study was to examine PS theory and methodology and compare application of three PS methods (matching, stratification, weighting) to determine which best improves confounder balance. Baseline characteristics of a sample of 20,518 school-aged children with severe obesity (of whom 1,054 received an obesity intervention) were assessed prior to PS application. Three PS methods were then applied to the data to determine which showed the greatest improvement in confounder balance between the intervention and control group. The effect of each PS method on the outcome variable-body mass index percentile change at one year-was also examined. SAS 9.4 and Comprehensive Meta-analysis statistical software were used for analyses. Prior to PS adjustment, the intervention and control groups differed significantly on seven of 11 potential confounders. PS matching removed all differences. PS stratification and weighting both removed one difference but created two new differences. Sensitivity analyses did not change these results. Body mass index percentile at 1 year decreased in both groups. The size of the decrease was smaller in the intervention group, and the estimate of the decrease varied by PS method. Selection of a PS method should be guided by insight from statistical theory and simulation experiments, in addition to observed improvement in confounder balance. For this data set, PS matching worked best to correct confounder imbalance. Because each method varied in correcting confounder imbalance, we recommend that multiple PS methods be compared for ability to improve confounder balance before implementation in evaluating treatment effects in observational data.

Measurement of Newton's constant using a torsion balance with angular acceleration feedback.

PubMed

Gundlach, J H; Merkowitz, S M

2000-10-02

We measured Newton's gravitational constant G using a new torsion balance method. Our technique greatly reduces several sources of uncertainty compared to previous measurements: (1) It is insensitive to anelastic torsion fiber properties; (2) a flat plate pendulum minimizes the sensitivity due to the pendulum density distribution; (3) continuous attractor rotation reduces background noise. We obtain G = (6.674215+/-0.000092) x 10(-11) m3 kg(-1) s(-2); the Earth's mass is, therefore, M = (5.972245+/-0.000082) x 10(24) kg and the Sun's mass is M = (1.988435+/-0.000027) x 10(30) kg.

Leak detection by mass balance effective for Norman Wells line

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liou, J.C.P.

Mass-balance calculations for leak detection have been shown as effective as a leading software system, in a comparison based on a major Canadian crude-oil pipeline. The calculations and NovaCorp`s Leakstop software each detected 4% (approximately) or greater leaks on Interprovincial Pipe Line (IPL) Inc.`s Norman Wells pipeline. Insufficient data exist to assess performances of the two methods for leaks smaller than 4%. Pipeline leak detection using such software-based systems are common. Their effectiveness is measured by how small and how quickly a leak can be detected. Algorithms used and measurement uncertainties determine leak detectability.

Mass Balance of a Maritime Glacier on the Southeast Tibetan Plateau and Its Climatic Sensitivity

NASA Astrophysics Data System (ADS)

Yang, W.

2014-12-01

Based on glacio-meteorological measurements and mass-balance stake records during the five-year period of 2005-2010 on the southeast Tibetan Plateau, an energy-mass balance model was applied to study the surface mass balance of the Parlung No. 94 Glacier, as well as its response to regional climate conditions. The primary physical parameters involved in the model were locally calibrated by using relevant glacio-meteorological datasets. The good agreement between the snowpack height/mass balance simulations and the in-situ measurements available from a total of 12 monitoring stakes over this glacier confirmed the satisfactory performance of the energy-mass balance model. Results suggested that the recent state of the Parlung No. 94 Glacier was far removed from the 'ideal' climatic regime leading to zero mass balance, with its annual mass balance of approximately -0.9 m w.e. during 2005-2010. Climatic sensitivity experiments were also carried out to interpret the observed mass-balance changes, and the experiments demonstrated that the maritime glaciers concerned herein were theoretically more vulnerable to ongoing climate warming on the Tibetan Plateau than potential changes in the amount of precipitation. A plausible causal explanation for the recent glacier shrinkage in this region was concerned with the increasing air temperature. Moreover, both the mass balance simulations and the field measurements indicated that the mass accumulation over this maritime glacier occurred primarily in the boreal spring. Such "spring-accumulation type" glaciers are presumed to be distributed mainly within a narrow wedge-shaped region along the Brahmaputra River. Climatic sensitivities of the glacier mass balanceare also found to be closely linked to the regional precipitation seasonality that is simultaneously modulated by various atmospheric circulation patterns, such as the southern westerlies, the Bay of Bengal vortex in the spring season and the Indian monsoon in the summer season.

Trends in ice sheet mass balance, 1992 to 2017

NASA Astrophysics Data System (ADS)

Shepherd, A.; Ivins, E. R.; Smith, B.; Velicogna, I.; Whitehouse, P. L.; Rignot, E. J.; van den Broeke, M. R.; Briggs, K.; Hogg, A.; Krinner, G.; Joughin, I. R.; Nowicki, S.; Payne, A. J.; Scambos, T.; Schlegel, N.; Moyano, G.; Konrad, H.

2017-12-01

The Ice Sheet Mass Balance Inter-Comparison Exercise (IMBIE) is a community effort, jointly supported by ESA and NASA, that aims to provide a consensus estimate of ice sheet mass balance from satellite gravimetry, altimetry and mass budget assessments, on an annual basis. The project has five experiment groups, one for each of the satellite techniques and two others to analyse surface mass balance (SMB) and glacial isostatic adjustment (GIA). The basic premise for the exercise is that individual ice sheet mass balance datasets are generated by project participants using common spatial and temporal domains to allow meaningful inter-comparison, and this controlled comparison in turn supports aggregation of the individual datasets over their full period. Participation is open to the full community, and the quality and consistency of submissions is regulated through a series of data standards and documentation requirements. The second phase of IMBIE commenced in 2015, with participant data submitted in 2016 and a combined estimate due for public release in 2017. Data from 48 participant groups were submitted to one of the three satellite mass balance technique groups or to the ancillary dataset groups. The individual mass balance estimates and ancillary datasets have been compared and combined within the respective groups. Following this, estimates of ice sheet mass balance derived from the individual techniques were then compared and combined. The result is single estimates of ice sheet mass balance for Greenland, East Antarctica, West Antarctica, and the Antarctic Peninsula. The participants, methodology and results of the exercise will be presented in this paper.

Dynamic Stability and Gravitational Balancing of Multiple Extended Bodies

NASA Technical Reports Server (NTRS)

Quadrelli, Marco

2008-01-01

Feasibility of a non-invasive compensation scheme was analyzed for precise positioning of a massive extended body in free fall using gravitational forces influenced by surrounding source masses in close proximity. The N-body problem of classical mechanics is a paradigm used to gain insight into the physics of the equivalent N-body problem subject to control forces. The analysis addressed how a number of control masses move around the proof mass so that the proof mass position can be accurately and remotely compensated when exogenous disturbances are acting on it, while its sensitivity to gravitational waves remains unaffected. Past methods to correct the dynamics of the proof mass have considered active electrostatic or capacitive methods, but the possibility of stray capacitances on the surfaces of the proof mass have prompted the investigation of other alternatives, such as the method presented in this paper. While more rigorous analyses of the problem should be carried out, the data show that, by means of a combined feedback and feed-forward control approach, the control masses succeeded in driving the proof mass along the specified trajectory, which implies that the proof mass can, in principle, be balanced via gravitational forces only while external perturbations are acting on it. This concept involves the dynamic stability of a group of massive objects interacting gravitationally under active control, and can apply to drag-free control of spacecraft during missions, to successor gravitational wave space borne sensors, or to any application requiring flying objects to be precisely controlled in position and attitude relative to another body via gravitational interactions only.

Mass balance computation in SAGUARO

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baker, B.L.; Eaton, R.R.

1986-12-01

This report describes the development of the mass balance subroutines used with the finite-element code, SAGUARO, which models fluid flow in partially saturated porous media. Derivation of the basic mass storage and mass flux equations is included. The results of the SAGUARO mass-balance subroutine, MASS, are shown to compare favorably with the linked results of FEMTRAN. Implementation of the MASS option in SAGUARO is described. Instructions for use of the MASS option are demonstrated with the three sample cases.

Application of a data reconciliation method to the stoichiometric analysis of Fibrobacter succinogenes growth.

PubMed

Guiavarch, Erell; Pons, Agnes; Creuly, Catherine; Dussap, Claude-Gilles

2008-12-01

Fibrobacter succinogenes S85, a strictly anaerobic Gram-negative bacterium, was grown in continuous culture in a bioreactor at different dilution rates (0.02 to 0.092 h(-1)) on a fully synthetic culture medium with glucose as carbon source. Glucose and ammonium sulfate consumption, as well as biomass, succinate, acetate, formate, and carbohydrate production were regularly measured. The relevant biomass elemental compositions were established for each dilution rate. Robustness of the experimental information was checked by C and N mass balances estimation, which were satisfactory. A detailed overall stoichiometry analysis of the process, including all substrates and products of the culture, was proposed. Online and off-line parameters measured during the culture brought a large number of data which were weighted by their respective variance associated to the measured value. The material balance resulted in an overdetermined linear system of equations made of weighted relationships including experimental data, elemental balances (C, H, O, N, S, Na), and an additional constraint. The mass balances involved in stoichiometric equations were solved using data reconciliation and linear algebra methods to take into account error measurements. This methodology allowed to establish the overall stoichiometric equation for each dilution rate studied.

Glacier modeling in support of field observations of mass balance at South Cascade Glacier, Washington, USA

USGS Publications Warehouse

Josberger, Edward G.; Bidlake, William R.

2010-01-01

The long-term USGS measurement and reporting of mass balance at South Cascade Glacier was assisted in balance years 2006 and 2007 by a new mass balance model. The model incorporates a temperature-index melt computation and accumulation is modeled from glacier air temperature and gaged precipitation at a remote site. Mass balance modeling was used with glaciological measurements to estimate dates and magnitudes of critical mass balance phenomena. In support of the modeling, a detailed analysis was made of the "glacier cooling effect" that reduces summer air temperature near the ice surface as compared to that predicted on the basis of a spatially uniform temperature lapse rate. The analysis was based on several years of data from measurements of near-surface air temperature on the glacier. The 2006 and 2007 winter balances of South Cascade Glacier, computed with this new, model-augmented methodology, were 2.61 and 3.41 mWE, respectively. The 2006 and 2007 summer balances were -4.20 and -3.63 mWE, respectively, and the 2006 and 2007 net balances were -1.59 and -0.22 mWE. PDF version of a presentation on the mass balance of South Cascade Glacier in Washington state. Presented at the American Geophysical Union Fall Meeting 2010.

Land motion due to 20th century mass balance of the Greenland Ice Sheet

NASA Astrophysics Data System (ADS)

Kjeldsen, K. K.; Khan, S. A.

2017-12-01

Quantifying the contribution from ice sheets and glaciers to past sea level change is of great value for understanding sea level projections into the 21st century. However, quantifying and understanding past changes are equally important, in particular understanding the impact in the near-field where the signal is highest. We assess the impact of 20th century mass balance of the Greenland Ice Sheet on land motion using results from Kjeldsen et al, 2015. These results suggest that the ice sheet on average lost a minimum of 75 Gt/yr, but also show that the mass balance was highly spatial- and temporal variable, and moreover that on a centennial time scale changes were driven by a decreasing surface mass balance. Based on preliminary results we discuss land motion during the 20th century due to mass balance changes and the driving components surface mass balance and ice dynamics.

Using vadose zone data and spatial statistics to assess the impact of cultivated land and dairy waste lagoons on groundwater contamination

NASA Astrophysics Data System (ADS)

Baram, S.; Ronen, Z.; Kurtzman, D.; Peeters, A.; Dahan, O.

2013-12-01

Land cultivation and dairy waste lagoons are considered to be nonpoint and point sources of groundwater contamination by chloride (Cl-) and nitrate (NO3-). The objective of this work is to introduce a methodology to assess the past and future impacts of such agricultural activities on regional groundwater quality. The method is based on mass balances and on spatial statistical analysis of Cl- and NO3-concentration distributions in the saturated and unsaturated zones. The method enables quantitative analysis of the relation between the locations of pollution point sources and the spatial variability in Cl- and NO3- concentrations in groundwater. The method was applied to the Beer-Tuvia region, Israel, where intensive dairy farming along with land cultivation has been practiced for over 50 years above the local phreatic aquifer. Mass balance calculations accounted for the various groundwater recharge and abstraction sources and sinks in the entire region. The mass balances showed that leachates from lagoons and the cultivated land have contributed 6.0 and 89.4 % of the total mass of Cl- added to the aquifer and 12.6 and 77.4 % of the total mass of NO3-. The chemical composition of the aquifer and vadose zone water suggested that irrigated agricultural activity in the region is the main contributor of Cl- and NO3- to the groundwater. A low spatial correlation between the Cl- and NO3- concentrations in the groundwater and the on-land location of the dairy farms strengthened this assumption, despite the dairy waste lagoon being a point source for groundwater contamination by Cl- and NO3-. Results demonstrate that analyzing vadose zone and groundwater data by spatial statistical analysis methods can significantly contribute to the understanding of the relations between groundwater contaminating sources, and to assessing appropriate remediation steps.

Quantifying the fate of agricultural nitrogen in an unconfined aquifer: Stream-based observations at three measurement scales

NASA Astrophysics Data System (ADS)

Gilmore, Troy E.; Genereux, David P.; Solomon, D. Kip; Solder, John E.; Kimball, Briant A.; Mitasova, Helena; Birgand, François

2016-03-01

We compared three stream-based sampling methods to study the fate of nitrate in groundwater in a coastal plain watershed: point measurements beneath the streambed, seepage blankets (novel seepage-meter design), and reach mass-balance. The methods gave similar mean groundwater seepage rates into the stream (0.3-0.6 m/d) during two 3-4 day field campaigns despite an order of magnitude difference in stream discharge between the campaigns. At low flow, estimates of flow-weighted mean nitrate concentrations in groundwater discharge ([NO3-]FWM) and nitrate flux from groundwater to the stream decreased with increasing degree of channel influence and measurement scale, i.e., [NO3-]FWM was 654, 561, and 451 µM for point, blanket, and reach mass-balance sampling, respectively. At high flow the trend was reversed, likely because reach mass-balance captured inputs from shallow transient high-nitrate flow paths while point and blanket measurements did not. Point sampling may be better suited to estimating aquifer discharge of nitrate, while reach mass-balance reflects full nitrate inputs into the channel (which at high flow may be more than aquifer discharge due to transient flow paths, and at low flow may be less than aquifer discharge due to channel-based nitrate removal). Modeling dissolved N2 from streambed samples suggested (1) about half of groundwater nitrate was denitrified prior to discharge from the aquifer, and (2) both extent of denitrification and initial nitrate concentration in groundwater (700-1300 µM) were related to land use, suggesting these forms of streambed sampling for groundwater can reveal watershed spatial relations relevant to nitrate contamination and fate in the aquifer.

Measuring masses of single bacterial whole cells with a quadrupole ion trap.

PubMed

Peng, Wen-Ping; Yang, Yi-Chang; Kang, Ming-Wei; Lee, Yuan T; Chang, Huan-Cheng

2004-09-29

A novel method has been developed to precisely measure the masses of single bacterial whole cells using a quadrupole ion trap as an electrodynamic balance. The bacterial cells were introduced into the ion trap by matrix-assisted laser desorption/ionization, confined in space by audio frequency ac fields, and detected by elastic light scattering. Mass measurement accuracy approaching 0.1% was achieved for Escherichia coli K-12 with a mass distribution of +/-3% from 60 repetitive measurements of the particles and their clusters. This is the first high-precision mass measurement reported for any intact microorganisms with masses greater than 1 x 1010 Da. The method opens new avenues for high-precision mass measurement of single microbial particles and offers an alternative approach for rapid identification of microorganisms by mass spectrometry.

Contrasts between estimates of baseflow help discern multiple sources of water contributing to rivers

NASA Astrophysics Data System (ADS)

Cartwright, I.; Gilfedder, B.; Hofmann, H.

2014-01-01

This study compares baseflow estimates using chemical mass balance, local minimum methods, and recursive digital filters in the upper reaches of the Barwon River, southeast Australia. During the early stages of high-discharge events, the chemical mass balance overestimates groundwater inflows, probably due to flushing of saline water from wetlands and marshes, soils, or the unsaturated zone. Overall, however, estimates of baseflow from the local minimum and recursive digital filters are higher than those based on chemical mass balance using Cl calculated from continuous electrical conductivity measurements. Between 2001 and 2011, the baseflow contribution to the upper Barwon River calculated using chemical mass balance is between 12 and 25% of the annual discharge with a net baseflow contribution of 16% of total discharge. Recursive digital filters predict higher baseflow contributions of 19 to 52% of discharge annually with a net baseflow contribution between 2001 and 2011 of 35% of total discharge. These estimates are similar to those from the local minimum method (16 to 45% of annual discharge and 26% of total discharge). These differences most probably reflect how the different techniques characterise baseflow. The local minimum and recursive digital filters probably aggregate much of the water from delayed sources as baseflow. However, as many delayed transient water stores (such as bank return flow, floodplain storage, or interflow) are likely to be geochemically similar to surface runoff, chemical mass balance calculations aggregate them with the surface runoff component. The difference between the estimates is greatest following periods of high discharge in winter, implying that these transient stores of water feed the river for several weeks to months at that time. Cl vs. discharge variations during individual flow events also demonstrate that inflows of high-salinity older water occurs on the rising limbs of hydrographs followed by inflows of low-salinity water from the transient stores as discharge falls. The joint use of complementary techniques allows a better understanding of the different components of water that contribute to river flow, which is important for the management and protection of water resources.

Mechanisms of protein balance in skeletal muscle.

PubMed

Anthony, T G

2016-07-01

Increased global demand for adequate protein nutrition against a backdrop of climate change and concern for animal agriculture sustainability necessitates new and more efficient approaches to livestock growth and production. Anabolic growth is achieved when rates of new synthesis exceed turnover, producing a positive net protein balance. Conversely, deterioration or atrophy of lean mass is a consequence of a net negative protein balance. During early life and periods of growth, muscle mass is driven by increases in protein synthesis at the level of mRNA translation. Throughout life, muscle mass is further influenced by degradative processes such as autophagy and the ubiquitin proteasome pathway. Multiple signal transduction networks guide and coordinate these processes alongside quality control mechanisms to maintain protein homeostasis (proteostasis). Genetics, hormones, and environmental stimuli each influence proteostasis control, altering capacity and/or efficiency of muscle growth. An overview of recent findings and current methods to assess muscle protein balance and proteostasis is presented. Current efforts to identify novel control points have the potential through selective breeding design or development of hormetic strategies to better promote growth and health span during environmental stress. Copyright © 2016 Elsevier Inc. All rights reserved.

Body Segment Differences in Surface Area, Skin Temperature and 3D Displacement and the Estimation of Heat Balance during Locomotion in Hominins

PubMed Central

Cross, Alan; Collard, Mark; Nelson, Andrew

2008-01-01

The conventional method of estimating heat balance during locomotion in humans and other hominins treats the body as an undifferentiated mass. This is problematic because the segments of the body differ with respect to several variables that can affect thermoregulation. Here, we report a study that investigated the impact on heat balance during locomotion of inter-segment differences in three of these variables: surface area, skin temperature and rate of movement. The approach adopted in the study was to generate heat balance estimates with the conventional method and then compare them with heat balance estimates generated with a method that takes into account inter-segment differences in surface area, skin temperature and rate of movement. We reasoned that, if the hypothesis that inter-segment differences in surface area, skin temperature and rate of movement affect heat balance during locomotion is correct, the estimates yielded by the two methods should be statistically significantly different. Anthropometric data were collected on seven adult male volunteers. The volunteers then walked on a treadmill at 1.2 m/s while 3D motion capture cameras recorded their movements. Next, the conventional and segmented methods were used to estimate the volunteers' heat balance while walking in four ambient temperatures. Lastly, the estimates produced with the two methods were compared with the paired t-test. The estimates of heat balance during locomotion yielded by the two methods are significantly different. Those yielded by the segmented method are significantly lower than those produced by the conventional method. Accordingly, the study supports the hypothesis that inter-segment differences in surface area, skin temperature and rate of movement impact heat balance during locomotion. This has important implications not only for current understanding of heat balance during locomotion in hominins but also for how future research on this topic should be approached. PMID:18560580

Body segment differences in surface area, skin temperature and 3D displacement and the estimation of heat balance during locomotion in hominins.

PubMed

Cross, Alan; Collard, Mark; Nelson, Andrew

2008-06-18

The conventional method of estimating heat balance during locomotion in humans and other hominins treats the body as an undifferentiated mass. This is problematic because the segments of the body differ with respect to several variables that can affect thermoregulation. Here, we report a study that investigated the impact on heat balance during locomotion of inter-segment differences in three of these variables: surface area, skin temperature and rate of movement. The approach adopted in the study was to generate heat balance estimates with the conventional method and then compare them with heat balance estimates generated with a method that takes into account inter-segment differences in surface area, skin temperature and rate of movement. We reasoned that, if the hypothesis that inter-segment differences in surface area, skin temperature and rate of movement affect heat balance during locomotion is correct, the estimates yielded by the two methods should be statistically significantly different. Anthropometric data were collected on seven adult male volunteers. The volunteers then walked on a treadmill at 1.2 m/s while 3D motion capture cameras recorded their movements. Next, the conventional and segmented methods were used to estimate the volunteers' heat balance while walking in four ambient temperatures. Lastly, the estimates produced with the two methods were compared with the paired t-test. The estimates of heat balance during locomotion yielded by the two methods are significantly different. Those yielded by the segmented method are significantly lower than those produced by the conventional method. Accordingly, the study supports the hypothesis that inter-segment differences in surface area, skin temperature and rate of movement impact heat balance during locomotion. This has important implications not only for current understanding of heat balance during locomotion in hominins but also for how future research on this topic should be approached.

Effect of body mass index and fat mass on balance force platform measurements during a one-legged stance in older adults.

PubMed

Pereira, Camila; Silva, Rubens A da; de Oliveira, Marcio R; Souza, Rejane D N; Borges, Renata J; Vieira, Edgar R

2018-05-01

The purpose of this study was to evaluate the impact of body mass index (BMI) and fat mass on balance force platform measurements in older adults. The sample consisted of 257 participants who were stratified into four groups by BMI: low weight, normal weight, pre-obesity and obesity. For fat mass variables, older individuals were classified into low and high-fat mass. All groups investigated performed three trials of one-legged stance balance on a force platform. Center of pressure (COP) domain parameters were computed from the mean across trials. Analysis of variance results revealed no significant interactions for groups and sexes for all COP parameters. Comparable balance results were found for BMI and fat groups for all COP parameters. A statistical effect (P < 0.05) was only reported for sex differences for COP parameters, regardless of BMI and fat mass variables. Overall, women presented better balance than men. In conclusion, BMI and fat mass do not seem to influence the balance of older adults during a one-leg stance task.

Quantifying time-varying ground-water discharge and recharge in wetlands of the northern Florida Everglades

USGS Publications Warehouse

Choi, J.; Harvey, J.W.

2000-01-01

Developing a more thorough understanding of water and chemical budgets in wetlands depends in part on our ability to quantify time-varying interactions between ground water and surface water. We used a combined water and solute mass balance approach to estimate time-varying ground-water discharge and recharge in the Everglades Nutrient Removal project (ENR), a relatively large constructed wetland (1544 hectare) built for removing nutrients from agricultural drainage in the norther Everglades in South Florida, USA. Over a 4-year period (1994 through 1998), ground-water recharge averaged 13.4 hectare-meter per day (ha-m/day) or 0.9 cm/day, which is approximately 31% of surface water pumped into the ENR for treatment. In contrast, ground-water discharge was much smaller (1.4 ha-m/day, or 0.09 cm/day, or 2.8% of water input to ENR for treatment). Using a water-balance approach alone only allowed net ground-water exchange (discharge - recharge) to be estimated (-12 ?? 2.4 ha-ma/day). Disharge and recharge were individually determined by combining a chloride mass balance with the water balance. For a variety of reasons, the ground-water discharge estimated by the combined mass balance approach was not reliable (1.4 ?? 37 ha-m/day). As a result, ground-water interactions could only be reliably estimated by comparing the mass-balance results with other independent approaches, including direct seepage-meter measurements and previous estimates using ground-water modeling. All three independent approaches provided similar estimates of average ground-water recharge, ranging from 13 to 14 ha-m/day. There was also relatively good agreement between ground-water discharge estimates for the mass balance and seepage meter methods, 1.4 and 0.9 ha-m/day, respectively. However, ground-water-flow modeling provided an average discharge estimate that was approximately a factor of four higher (5.4 ha-m/day) than the other two methods. Our study developed an initial understanding of how the design and operation of the ENR increases interactions between ground water and surface water. A considerable portion of recharged ground water (73%) was collected and returned to the ENR by a seepage canal. Additional recharge that was not captured by the seepage canal only occurred when pumped inflow rates to ENR (and ENR water levels) were relatively high. Management of surface water in the northern Everglades therefore clearly has the potential to increase interactions with ground water.

Experimental aspects of buoyancy correction in measuring reliable high-pressure excess adsorption isotherms using the gravimetric method

NASA Astrophysics Data System (ADS)

Nguyen, Huong Giang T.; Horn, Jarod C.; Thommes, Matthias; van Zee, Roger D.; Espinal, Laura

2017-12-01

Addressing reproducibility issues in adsorption measurements is critical to accelerating the path to discovery of new industrial adsorbents and to understanding adsorption processes. A National Institute of Standards and Technology Reference Material, RM 8852 (ammonium ZSM-5 zeolite), and two gravimetric instruments with asymmetric two-beam balances were used to measure high-pressure adsorption isotherms. This work demonstrates how common approaches to buoyancy correction, a key factor in obtaining the mass change due to surface excess gas uptake from the apparent mass change, can impact the adsorption isotherm data. Three different approaches to buoyancy correction were investigated and applied to the subcritical CO2 and supercritical N2 adsorption isotherms at 293 K. It was observed that measuring a collective volume for all balance components for the buoyancy correction (helium method) introduces an inherent bias in temperature partition when there is a temperature gradient (i.e. analysis temperature is not equal to instrument air bath temperature). We demonstrate that a blank subtraction is effective in mitigating the biases associated with temperature partitioning, instrument calibration, and the determined volumes of the balance components. In general, the manual and subtraction methods allow for better treatment of the temperature gradient during buoyancy correction. From the study, best practices specific to asymmetric two-beam balances and more general recommendations for measuring isotherms far from critical temperatures using gravimetric instruments are offered.

Experimental aspects of buoyancy correction in measuring reliable highpressure excess adsorption isotherms using the gravimetric method.

PubMed

Nguyen, Huong Giang T; Horn, Jarod C; Thommes, Matthias; van Zee, Roger D; Espinal, Laura

2017-12-01

Addressing reproducibility issues in adsorption measurements is critical to accelerating the path to discovery of new industrial adsorbents and to understanding adsorption processes. A National Institute of Standards and Technology Reference Material, RM 8852 (ammonium ZSM-5 zeolite), and two gravimetric instruments with asymmetric two-beam balances were used to measure high-pressure adsorption isotherms. This work demonstrates how common approaches to buoyancy correction, a key factor in obtaining the mass change due to surface excess gas uptake from the apparent mass change, can impact the adsorption isotherm data. Three different approaches to buoyancy correction were investigated and applied to the subcritical CO 2 and supercritical N 2 adsorption isotherms at 293 K. It was observed that measuring a collective volume for all balance components for the buoyancy correction (helium method) introduces an inherent bias in temperature partition when there is a temperature gradient (i.e. analysis temperature is not equal to instrument air bath temperature). We demonstrate that a blank subtraction is effective in mitigating the biases associated with temperature partitioning, instrument calibration, and the determined volumes of the balance components. In general, the manual and subtraction methods allow for better treatment of the temperature gradient during buoyancy correction. From the study, best practices specific to asymmetric two-beam balances and more general recommendations for measuring isotherms far from critical temperatures using gravimetric instruments are offered.

Characterization of methane oxidation in a simulated landfill cover system by comparing molecular and stable isotope mass balances.

PubMed

Schulte, Marcel; Jochmann, Maik A; Gehrke, Tobias; Thom, Andrea; Ricken, Tim; Denecke, Martin; Schmidt, Torsten C

2017-11-01

Biological methane oxidation may be regarded as a method of aftercare treatment for landfills to reduce climate relevant methane emissions. It is of social and economic interest to estimate the behavior of bacterial methane oxidation in aged landfill covers due to an adequate long-term treatment of the gas emissions. Different approaches assessing methane oxidation in laboratory column studies have been investigated by other authors recently. However, this work represents the first study in which three independent approaches, ((i) mass balance, (ii) stable isotope analysis, and (iii) stoichiometric balance of product (CO 2 ) and reactant (CH 4 ) by CO 2 /CH 4 -ratio) have been compared for the estimation of the biodegradation by a robust statistical validation on a rectangular, wide soil column. Additionally, an evaluation by thermal imaging as a potential technique for the localization of the active zone of bacterial methane oxidation has been addressed in connection with stable isotope analysis and CO 2 /CH 4 -ratios. Although landfills can be considered as open systems the results for stable isotope analysis based on a closed system correlated better with the mass balance than calculations based on an open system. CO 2 /CH 4 -ratios were also in good agreement with mass balance. In general, highest values for biodegradation were determined from mass balance, followed by CO 2 /CH 4 -ratio, and stable isotope analysis. The investigated topsoil proved to be very suitable as a potential cover layer by removing up to 99% of methane for CH 4 loads of 35-65gm -2 d -1 that are typical in the aftercare phase of landfills. Finally, data from stable isotope analysis and the CO 2 /CH 4 -ratios were used to trace microbial activity within the reactor system. It was shown that methane consumption and temperature increase, as a cause of high microbial activity, correlated very well. Copyright © 2017 Elsevier Ltd. All rights reserved.

Engine balance apparatus and accessory drive device

NASA Technical Reports Server (NTRS)

Egleston, Robert W. (Inventor)

2002-01-01

A balancing mechanism for an engine that has a rotating crankshaft and reciprocating pistons. The balancing mechanism comprises a primary balance mass assembly non-rotatably and removably affixed to the crankshaft. The primary mass assembly comprises a primary mass affixed to a primary hub portion and a primary cap portion removably affixed to the primary hub portion to clamp a portion of the crankshaft therebetween. A secondary balance mass assembly may be rotatably and removably supported on the crankshaft. A driver assembly is affixed to the crankshaft to cause the secondary balance mass to rotate in a direction that is opposite to the direction in which the crank shaft is rotating. The driver assembly may include auxiliary gears configured to transport rotary power to auxiliary components. The gears are readily detachable from the apparatus to facilitate inspection and repair operations.

Surface melt dominates Alaska glacier mass balance

USGS Publications Warehouse

Larsen Chris F,; Burgess, E; Arendt, A.A.; O'Neel, Shad; Johnson, A.J.; Kienholz, C.

2015-01-01

Mountain glaciers comprise a small and widely distributed fraction of the world's terrestrial ice, yet their rapid losses presently drive a large percentage of the cryosphere's contribution to sea level rise. Regional mass balance assessments are challenging over large glacier populations due to remote and rugged geography, variable response of individual glaciers to climate change, and episodic calving losses from tidewater glaciers. In Alaska, we use airborne altimetry from 116 glaciers to estimate a regional mass balance of −75 ± 11 Gt yr−1 (1994–2013). Our glacier sample is spatially well distributed, yet pervasive variability in mass balances obscures geospatial and climatic relationships. However, for the first time, these data allow the partitioning of regional mass balance by glacier type. We find that tidewater glaciers are losing mass at substantially slower rates than other glaciers in Alaska and collectively contribute to only 6% of the regional mass loss.

State of balance of the cryosphere

NASA Technical Reports Server (NTRS)

Van Der Veen, C. J.

1991-01-01

Available observations and mass balance estimates of the cryosphere are summarized. Problems discussed include mountain glaciers, the Greenland ice sheet, the Antarctic ice sheet, conventional glacier measurement techniques, and satellite applications in glacier mass balance studies. It is concluded that the interior part of the Greenland ice sheet is thickening or in near equilibrium. Estimates of the mass balance of the Antarctic ice sheet suggest that it is positive, although the error limits allow for a slightly negative balance.

Modelled and observed mass balance of Rikha Samba Glacier, Nepal, Central Himalaya

NASA Astrophysics Data System (ADS)

Gurung, T. R.; Kayastha, R. B.; Fujita, K.; Sinisalo, A. K.; Stumm, D.; Joshi, S.; Litt, M.

2016-12-01

Glacier mass balance variability has an implication for the regional water resources and it helps to understand the response of glacier to climate change in the Himalayan region. Several mass balance studies have been started in the Himalayan region since 1970s, but they are characterized by frequent temporal gaps and a poor spatial representatively. This study aims at bridging the temporal gaps in a long term mass balance series of the Rikha Samba glacier (5383 - 6475 m a.s.l.), a benchmark glacier located in the Hidden Valley, Mustang, Nepal. The ERA Interim reanalysis data for the period 2011-2015 is calibrated with the observed meteorological variables from an AWS installed near the glacier terminus. We apply an energy mass balance model, validated with the available in-situ measurements for the years 1998 and 2011-2015. The results show that the glacier is shrinking at a moderate negative mass balance rate for the period 1995 to 2015 and the high altitude location of Rikha Samba also prevents a bigger mass loss compared to other small Himalayan glaciers. Precipitation from July to January and the mean air temperature from June to October are the most influential climatic parameters of the annual mass balance variability of Rikha Samba glacier.

MEASUREMENT OF VOCS DESORBED FROM BUILDING MATERIALS--A HIGH TEMPERATURE DYNAMIC CHAMBER METHOD

EPA Science Inventory

Mass balance is a commonly used approach for characterizing the source and sink behavior of building materials. Because the traditional sink test methods evaluate the adsorption and desorption of volatile organic compounds (VOC) at ambient temperatures, the desorption process is...

Mass-balance measurements in Alaska and suggestions for simplified observation programs

USGS Publications Warehouse

Trabant, D.C.; March, R.S.

1999-01-01

US Geological Survey glacier fieldwork in Alaska includes repetitious measurements, corrections for leaning or bending stakes, an ability to reliably measure seasonal snow as deep as 10 m, absolute identification of summer surfaces in the accumulation area, and annual evaluation of internal accumulation, internal ablation, and glacier-thickness changes. Prescribed field measurement and note-taking techniques help eliminate field errors and expedite the interpretative process. In the office, field notes are transferred to computerized spread-sheets for analysis, release on the World Wide Web, and archival storage. The spreadsheets have error traps to help eliminate note-taking and transcription errors. Rigorous error analysis ends when mass-balance measurements are extrapolated and integrated with area to determine glacier and basin mass balances. Unassessable errors in the glacier and basin mass-balance data reduce the value of the data set for correlations with climate change indices. The minimum glacier mass-balance program has at least three measurement sites on a glacier and the measurements must include the seasonal components of mass balance as well as the annual balance.

Estimation of evapotranspiration rate in irrigated lands using stable isotopes

NASA Astrophysics Data System (ADS)

Umirzakov, Gulomjon; Windhorst, David; Forkutsa, Irina; Brauer, Lutz; Frede, Hans-Georg

2013-04-01

Agriculture in the Aral Sea basin is the main consumer of water resources and due to the current agricultural management practices inefficient water usage causes huge losses of freshwater resources. There is huge potential to save water resources in order to reach a more efficient water use in irrigated areas. Therefore, research is required to reveal the mechanisms of hydrological fluxes in irrigated areas. This paper focuses on estimation of evapotranspiration which is one of the crucial components in the water balance of irrigated lands. Our main objective is to estimate the rate of evapotranspiration on irrigated lands and partitioning of evaporation into transpiration using stable isotopes measurements. Experiments has done in 2 different soil types (sandy and sandy loam) irrigated areas in Ferghana Valley (Uzbekistan). Soil samples were collected during the vegetation period. The soil water from these samples was extracted via a cryogenic extraction method and analyzed for the isotopic ratio of the water isotopes (2H and 18O) based on a laser spectroscopy method (DLT 100, Los Gatos USA). Evapotranspiration rates were estimated with Isotope Mass Balance method. The results of evapotranspiration obtained using isotope mass balance method is compared with the results of Catchment Modeling Framework -1D model results which has done in the same area and the same time.

Quantifying Tropical Glacier Mass Balance Sensitivity to Climate Change Through Regional-Scale Modeling and The Randolph Glacier Inventory

NASA Astrophysics Data System (ADS)

Malone, A.

2017-12-01

Quantifying mass balance sensitivity to climate change is essential for forecasting glacier evolution and deciphering climate signals embedded in archives of past glacier changes. Ideally, these quantifications result from decades of field measurement, remote sensing, and a hierarchy modeling approach, but in data-sparse regions, such as the Himalayas and tropical Andes, regional-scale modeling rooted in first principles provides a first-order picture. Previous regional-scaling modeling studies have applied a surface energy and mass balance approach in order to quantify equilibrium line altitude sensitivity to climate change. In this study, an expanded regional-scale surface energy and mass balance model is implemented to quantify glacier-wide mass balance sensitivity to climate change for tropical Andean glaciers. Data from the Randolph Glacier Inventory are incorporated, and additional physical processes are included, such as a dynamic albedo and cloud-dependent atmospheric emissivity. The model output agrees well with the limited mass balance records for tropical Andean glaciers. The dominant climate variables driving interannual mass balance variability differ depending on the climate setting. For wet tropical glaciers (annual precipitation >0.75 m y-1), temperature is the dominant climate variable. Different hypotheses for the processes linking wet tropical glacier mass balance variability to temperature are evaluated. The results support the hypothesis that glacier-wide mass balance on wet tropical glaciers is largely dominated by processes at the lowest elevation where temperature plays a leading role in energy exchanges. This research also highlights the transient nature of wet tropical glaciers - the vast majority of tropical glaciers and a vital regional water resource - in an anthropogenic warming world.

Determination of Interannual to Decadal Changes in Ice Sheet Mass Balance from Satellite Altimetry

NASA Technical Reports Server (NTRS)

Zwally, H. Jay; Busalacchi, Antonioa J. (Technical Monitor)

2001-01-01

A major uncertainty in predicting sea level rise is the sensitivity of ice sheet mass balance to climate change, as well as the uncertainty in present mass balance. Since the annual water exchange is about 8 mm of global sea level equivalent, the +/- 25% uncertainty in current mass balance corresponds to +/- 2 mm/yr in sea level change. Furthermore, estimates of the sensitivity of the mass balance to temperature change range from perhaps as much as - 10% to + 10% per K. Although the overall ice mass balance and seasonal and inter-annual variations can be derived from time-series of ice surface elevations from satellite altimetry, satellite radar altimeters have been limited in spatial coverage and elevation accuracy. Nevertheless, new data analysis shows mixed patterns of ice elevation increases and decreases that are significant in terms of regional-scale mass balances. In addition, observed seasonal and interannual variations in elevation demonstrate the potential for relating the variability in mass balance to changes in precipitation, temperature, and melting. From 2001, NASA's ICESat laser altimeter mission will provide significantly better elevation accuracy and spatial coverage to 86 deg latitude and to the margins of the ice sheets. During 3 to 5 years of ICESat-1 operation, an estimate of the overall ice sheet mass balance and sea level contribution will be obtained. The importance of continued ice monitoring after the first ICESat is illustrated by the variability in the area of Greenland surface melt observed over 17-years and its correlation with temperature. In addition, measurement of ice sheet changes, along with measurements of sea level change by a series of ocean altimeters, should enable direct detection of ice level and global sea level correlations.

The mass balance of the ice plain of Ice Stream B and Crary Ice Rise

NASA Technical Reports Server (NTRS)

Bindschadler, Robert

1993-01-01

The region in the mouth of Ice Stream B (the ice plain) and that in the vicinity of Crary Ice Rise are experiencing large and rapid changes. Based on velocity, ice thickness, and accumulation rate data, the patterns of net mass balance in these regions were calculated. Net mass balance, or the rate of ice thickness change, was calculated as the residual of all mass fluxes into and out of subregions (or boxes). Net mass balance provides a measure of the state of health of the ice sheet and clues to the current dynamics.

Shooting method for solution of boundary-layer flows with massive blowing

NASA Technical Reports Server (NTRS)

Liu, T.-M.; Nachtsheim, P. R.

1973-01-01

A modified, bidirectional shooting method is presented for solving boundary-layer equations under conditions of massive blowing. Unlike the conventional shooting method, which is unstable when the blowing rate increases, the proposed method avoids the unstable direction and is capable of solving complex boundary-layer problems involving mass and energy balance on the surface.

Local topography increasingly influences the mass balance of a retreating cirque glacier

USGS Publications Warehouse

Florentine, Caitlyn; Harper, Joel T.; Fagre, Daniel B.; Moore, Johnnie; Peitzsch, Erich H.

2018-01-01

Local topographically driven processes – such as wind drifting, avalanching, and shading – are known to alter the relationship between the mass balance of small cirque glaciers and regional climate. Yet partitioning such local effects from regional climate influence has proven difficult, creating uncertainty in the climate representativeness of some glaciers. We address this problem for Sperry Glacier in Glacier National Park, USA, using field-measured surface mass balance, geodetic constraints on mass balance, and regional climate data recorded at a network of meteorological and snow stations. Geodetically derived mass changes during 1950–1960, 1960–2005, and 2005–2014 document average mass change rates during each period at −0.22 ± 0.12, −0.18 ± 0.05, and −0.10 ± 0.03 m w.e. yr−1, respectively. A correlation of field-measured mass balance and regional climate variables closely (i.e., within 0.08 m w.e. yr−1) predicts the geodetically measured mass loss from 2005 to 2014. However, this correlation overestimates glacier mass balance for 1950–1960 by +1.20 ± 0.95 m w.e. yr−1. Our analysis suggests that local effects, not represented in regional climate variables, have become a more dominant driver of the net mass balance as the glacier lost 0.50 km2 and retreated further into its cirque.

Modeling and Understanding the Mass Balance of Himalayan Glaciers

NASA Astrophysics Data System (ADS)

Rengaraju, S.; Achutarao, K. M.

2017-12-01

Changes in glaciers are among the most visible manifestations of a changing climate. Retreating glaciers have significant impacts on global sea-level rise and stream flow of rivers. Modeling the response of glaciers to climate change is important for many reasons including predicting changes in global sea level and water resources. The mass balance of a glacier provides a robust way of ascertaining whether there has been a net loss or gain of ice from the glacier. The mass balance reflects all of the meteorological forcing of the glacier - from the accumulation of snow and the combined losses from ablation and sublimation. The glaciers in the Himalayan region are considered sensitive to climate change and their fate under climate change is critical to the billions of humans that rely on rivers originating from these glaciers. Owing to complex terrain and harsh climate, Himalayan glaciers have historically been poorly monitored and this makes it harder to understand and predict their fate.In this study we model the observed mass balance of Himalayan glaciers using the methods of Radic and Hock (2011) and analyze the response to future changes in climate based on the model projections from the Coupled Model Intercomparison Project Phase-5 (CMIP5; Taylor et al., 2012). We make use of available observations of mass balance from various sources for 14 glaciers across the Himalayas. These glaciers are located across distinct climatic conditions - from the Karakoram and Hindu Kush in the West that are fed by winter precipitation caused by westerly disturbances to the Eastern Himalayas where the summer monsoon provides the bulk of the precipitation. For the historical observed period, we use the ECMWF Re-Analysis (ERA-40) for temperature and VASClimO (GPCC) data at 2.5°x2.5° resolution to calibrate the mass balance model. We evaluate the CMIP5 model simulations for their fidelity in capturing the distinct climatic conditions across the Himalayas in order to select suitable models to study future response of the glaciers in this region. We also quantify the range and sources of uncertainty in projected changes.

Gas exchange rates across the sediment-water and air-water interfaces in south San Francisco Bay

USGS Publications Warehouse

Hartman, Blayne; Hammond, Douglas E.

1984-01-01

Radon 222 concentrations in the water and sedimentary columns and radon exchange rates across the sediment-water and air-water interfaces have been measured in a section of south San Francisco Bay. Two independent methods have been used to determine sediment-water exchange rates, and the annual averages of these methods agree within the uncertainty of the determinations, about 20%. The annual average of benthic fluxes from shoal areas is nearly a factor of 2 greater than fluxes from the channel areas. Fluxes from the shoal and channel areas exceed those expected from simple molecular diffusion by factors of 4 and 2, respectively, apparently due to macrofaunal irrigation. Values of the gas transfer coefficient for radon exchange across the air-water interface were determined by constructing a radon mass balance for the water column and by direct measurement using floating chambers. The chamber method appears to yield results which are too high. Transfer coefficients computed using the mass balance method range from 0.4 m/day to 1.8 m/day, with a 6-year average of 1.0 m/day. Gas exchange is linearly dependent upon wind speed over a wind speed range of 3.2–6.4 m/s, but shows no dependence upon current velocity. Gas transfer coefficients predicted from an empirical relationship between gas exchange rates and wind speed observed in lakes and the oceans are within 30% of the coefficients determined from the radon mass balance and are considerably more accurate than coefficients predicted from theoretical gas exchange models.

Improving Estimation of Submarine Groundwater Discharge Using Radium and Radon Tracers: Application in Jiaozhou Bay, China

NASA Astrophysics Data System (ADS)

Zhang, Yan; Li, Hailong; Xiao, Kai; Wang, Xuejing; Lu, Xiaoting; Zhang, Meng; An, An; Qu, Wenjing; Wan, Li; Zheng, Chunmiao; Wang, Xusheng; Jiang, Xiaowei

2017-10-01

Radium and radon mass balance models have been widely used to quantify submarine groundwater discharge (SGD) in the coastal areas. However, the losses of radium or radon in seawater caused by recirculated saline groundwater discharge (RSGD) are ignored in most of the previous studies for tracer-based models and this can lead to an underestimation of SGD. Here we present an improved method which considers the losses of tracers caused by RSGD to enhance accuracy in estimating SGD and SGD-associated material loadings. Theoretical analysis indicates that neglecting the losses of tracers induced by RSGD would underestimate the SGD by a percentage approximately equaling the tracer activity ratio of nearshore seawater to groundwater. The data analysis of previous typical case studies shows that the existing old models underestimated the SGD by 1.9-93%, with an average of 32.2%. The method is applied in Jiaozhou Bay (JZB), North China, which is experiencing significant environmental pollution. The SGD flux into JZB estimated by the improved method is ˜1.44 and 1.34 times of that estimated by the old method for 226Ra mass balance model and 228Ra mass balance model, respectively. Both SGD and RSGD fluxes are significantly higher than the discharge rate of Dagu River (the largest one running into JZB). The fluxes of nutrients and metals through SGD are comparable to or even higher than those from local rivers, which indicates that SGD is an important source of chemicals into JZB and has important impact on marine ecological system.

Solids mass flow determination

DOEpatents

Macko, Joseph E.

1981-01-01

Method and apparatus for determining the mass flow rate of solids mixed with a transport fluid to form a flowing mixture. A temperature differential is established between the solids and fluid. The temperature of the transport fluid prior to mixing, the temperature of the solids prior to mixing, and the equilibrium temperature of the mixture are monitored and correlated in a heat balance with the heat capacities of the solids and fluid to determine the solids mass flow rate.

Results of the Lake Michigan Mass Balance Project: Atrazine Modeling Report

EPA Science Inventory

This report covers an overview of chemical properties, measurements in air and water, model construct and assumptions, and results of mathematical mass balance modeling of the herbicide atrazine in the Lake Michigan basin. Within the context of the mass balance, an overview of a...

Engine balance apparatus and accessory drive device

NASA Technical Reports Server (NTRS)

Brogdon, James William (Inventor); Gill, David Keith (Inventor)

2000-01-01

A balancing mechanism for an engine that has a rotating crankshaft and reciprocating pistons such as those engines used in automobiles, aircrafts, boats, piston-driven compressors, piston-driven slider crank mechanisms, etc. The present balancing mechanism may comprise a first balance mass non-rotatably affixed to the crankshaft and a second balance mass rotatably supported on the crankshaft. A driver assembly is affixed to crankshaft to cause the second balance mass to rotate in a direction that is opposite to the direction in which the crank shaft is rotating. The driver assembly may include auxiliary gears configured to transport rotary power to auxiliary components.

40 CFR 98.123 - Calculating GHG emissions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... mass balance approach to estimate your fluorinated GHG emissions from a process, you must ensure that... relative errors associated with using the mass balance approach on that process using Equations L-1 through... mass-balance approach to estimate emissions from the process if this calculation results in an absolute...

40 CFR 98.123 - Calculating GHG emissions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... mass balance approach to estimate your fluorinated GHG emissions from a process, you must ensure that... relative errors associated with using the mass balance approach on that process using Equations L-1 through... mass-balance approach to estimate emissions from the process if this calculation results in an absolute...

40 CFR 98.123 - Calculating GHG emissions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... mass balance approach to estimate your fluorinated GHG emissions from a process, you must ensure that... relative errors associated with using the mass balance approach on that process using Equations L-1 through... mass-balance approach to estimate emissions from the process if this calculation results in an absolute...

40 CFR 98.123 - Calculating GHG emissions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... mass balance approach to estimate your fluorinated GHG emissions from a process, you must ensure that... relative errors associated with using the mass balance approach on that process using Equations L-1 through... mass-balance approach to estimate emissions from the process if this calculation results in an absolute...

Steady state phosphorus mass balance model during hemodialysis based on a pseudo one-compartment kinetic model.

PubMed

Leypoldt, John K; Agar, Baris U; Akonur, Alp; Gellens, Mary E; Culleton, Bruce F

2012-11-01

Mathematical models of phosphorus kinetics and mass balance during hemodialysis are in early development. We describe a theoretical phosphorus steady state mass balance model during hemodialysis based on a novel pseudo one-compartment kinetic model. The steady state mass balance model accounted for net intestinal absorption of phosphorus and phosphorus removal by both dialysis and residual kidney function. Analytical mathematical solutions were derived to describe time-dependent intradialytic and interdialytic serum phosphorus concentrations assuming hemodialysis treatments were performed symmetrically throughout a week. Results from the steady state phosphorus mass balance model are described for thrice weekly hemodialysis treatment prescriptions only. The analysis predicts 1) a minimal impact of dialyzer phosphorus clearance on predialysis serum phosphorus concentration using modern, conventional hemodialysis technology, 2) variability in the postdialysis-to-predialysis phosphorus concentration ratio due to differences in patient-specific phosphorus mobilization, and 3) the importance of treatment time in determining the predialysis serum phosphorus concentration. We conclude that a steady state phosphorus mass balance model can be developed based on a pseudo one-compartment kinetic model and that predictions from this model are consistent with previous clinical observations. The predictions from this mass balance model are theoretical and hypothesis-generating only; additional prospective clinical studies will be required for model confirmation.

Evaluation of methods for measuring particulate matter emissions from gas turbines.

PubMed

Petzold, Andreas; Marsh, Richard; Johnson, Mark; Miller, Michael; Sevcenco, Yura; Delhaye, David; Ibrahim, Amir; Williams, Paul; Bauer, Heidi; Crayford, Andrew; Bachalo, William D; Raper, David

2011-04-15

The project SAMPLE evaluated methods for measuring particle properties in the exhaust of aircraft engines with respect to the development of standardized operation procedures for particulate matter measurement in aviation industry. Filter-based off-line mass methods included gravimetry and chemical analysis of carbonaceous species by combustion methods. Online mass methods were based on light absorption measurement or used size distribution measurements obtained from an electrical mobility analyzer approach. Number concentrations were determined using different condensation particle counters (CPC). Total mass from filter-based methods balanced gravimetric mass within 8% error. Carbonaceous matter accounted for 70% of gravimetric mass while the remaining 30% were attributed to hydrated sulfate and noncarbonaceous organic matter fractions. Online methods were closely correlated over the entire range of emission levels studied in the tests. Elemental carbon from combustion methods and black carbon from optical methods deviated by maximum 5% with respect to mass for low to medium emission levels, whereas for high emission levels a systematic deviation between online methods and filter based methods was found which is attributed to sampling effects. CPC based instruments proved highly reproducible for number concentration measurements with a maximum interinstrument standard deviation of 7.5%.

Identification of dynamic characteristics of flexible rotors as dynamic inverse problem

NASA Technical Reports Server (NTRS)

Roisman, W. P.; Vajingortin, L. D.

1991-01-01

The problem of dynamic and balancing of flexible rotors were considered, which were set and solved as the problem of the identification of flexible rotor systems, which is the same as the inverse problem of the oscillation theory dealing with the task of the identifying the outside influences and system parameters on the basis of the known laws of motion. This approach to the problem allows the disclosure the picture of disbalances throughout the rotor-under-test (which traditional methods of flexible rotor balancing, based on natural oscillations, could not provide), and identify dynamic characteristics of the system, which correspond to a selected mathematical model. Eventually, various methods of balancing were developed depending on the special features of the machines as to their design, technology, and operation specifications. Also, theoretical and practical methods are given for the flexible rotor balancing at far from critical rotation frequencies, which does not necessarily require the knowledge forms of oscillation, dissipation, and elasticity and inertia characteristics, and to use testing masses.

Myths and methodologies: Making sense of exercise mass and water balance.

PubMed

Cheuvront, Samuel N; Montain, Scott J

2017-09-01

What is the topic of this review? There is a need to revisit the basic principles of exercise mass and water balance, the use of common equations and the practice of interpreting outcomes. What advances does it highlight? We propose use of the following equation as a way of simplifying exercise mass and water balance calculations in conditions where food is not consumed and waste is not excreted: ∆body mass - 0.20 g/kcal -1  = ∆body water. The relative efficacy of exercise drinking behaviours can be judged using the following equation: percentage dehydration = [(∆body mass - 0.20 g kcal -1 )/starting body mass] × 100. Changes in body mass occur because of flux in liquids, solids and gases. This knowledge is crucial for understanding metabolism, health and human water needs. In exercise science, corrections to observed changes in body mass to estimate water balance are inconsistently applied and often misinterpreted, particularly after prolonged exercise. Although acute body mass losses in response to exercise can represent a close surrogate for body water losses, the discordance between mass and water balance equivalence becomes increasingly inaccurate as more and more energy is expended. The purpose of this paper is briefly to clarify the roles that respiratory water loss, gas exchange and metabolic water production play in the correction of body mass changes for fluid balance determinations during prolonged exercise. Computations do not include waters of association with glycogen because any movement of water among body water compartments contributes nothing to water or mass flux from the body. Estimates of sweat loss from changes in body mass should adjust for non-sweat losses when possible. We propose use of the following equation as a way of simplifying the study of exercise mass and water balance: ∆body mass - 0.20 g kcal -1  = ∆body water. This equation directly controls for the influence of energy expenditure on body mass balance and the approximate offsetting equivalence of respiratory water loss and metabolic water production on body water balance. The relative efficacy of exercise drinking behaviours can be judged using the following equation: percentage dehydration = [(∆body mass - 0.20 g kcal -1 )/starting body mass] × 100. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

Methods for Combination of GRACE Gravimetry and ICESat Altimetry over Antarctica on Monthly Timescales

NASA Astrophysics Data System (ADS)

Hardy, R. A.; Nerem, R. S.; Wiese, D. N.

2017-12-01

Gravity and surface elevation change data altimetry provide different perspectives on mass variability in Antarctica. In anticipation of the concurrent operation of the successors of GRACE and ICESat, GRACE Follow-On and ICESat-2, we approach the problem of combining these data for enhanced spatial resolution and disaggregation of Antarctica's major mass transport processes. Using elevation changes gathered from over 500 million overlapping ICESat laser shot pairs between 2003 and 2009, we construct gridded models of Antarctic elevation change for each ICESat operational period. Comparing these elevation grids with temporally registered JPL RL05M mascon solutions, we exploit the relationship between surface mass flux and elevation change to inform estimates of effective surface density. These density estimates enable solutions for glacial isostatic adjustment and monthly estimates of surface mass change. These are used alongside spatial statistics from both the data and models of surface mass balance to produce enhanced estimates of Antarctic mass balance. We validate our solutions by modeling the effects of elastic loading and GIA from these solutions on the vertical motion of Antarctica's GNSS sites.

40 CFR 98.114 - Monitoring and QA/QC requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... requirements. If you determine annual process CO2 emissions using the carbon mass balance procedure in § 98.113... D5373-08 Standard Test Methods for Instrumental Determination of Carbon, Hydrogen, and Nitrogen in...

40 CFR 98.114 - Monitoring and QA/QC requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... requirements. If you determine annual process CO2 emissions using the carbon mass balance procedure in § 98.113... D5373-08 Standard Test Methods for Instrumental Determination of Carbon, Hydrogen, and Nitrogen in...

40 CFR 98.114 - Monitoring and QA/QC requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

... requirements. If you determine annual process CO2 emissions using the carbon mass balance procedure in § 98.113... D5373-08 Standard Test Methods for Instrumental Determination of Carbon, Hydrogen, and Nitrogen in...

40 CFR 98.114 - Monitoring and QA/QC requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... requirements. If you determine annual process CO2 emissions using the carbon mass balance procedure in § 98.113... D5373-08 Standard Test Methods for Instrumental Determination of Carbon, Hydrogen, and Nitrogen in...

Mass balance approaches for estimating the intestinal absorption and metabolism of peptides and analogues: theoretical development and applications

NASA Technical Reports Server (NTRS)

Sinko, P. J.; Leesman, G. D.; Amidon, G. L.

1993-01-01

A theoretical analysis for estimating the extent of intestinal peptide and peptide analogue absorption was developed on the basis of a mass balance approach that incorporates convection, permeability, and reaction. The macroscopic mass balance analysis (MMBA) was extended to include chemical and enzymatic degradation. A microscopic mass balance analysis, a numerical approach, was also developed and the results compared to the MMBA. The mass balance equations for the fraction of a drug absorbed and reacted in the tube were derived from the general steady state mass balance in a tube: [formula: see text] where M is mass, z is the length of the tube, R is the tube radius, Pw is the intestinal wall permeability, kr is the reaction rate constant, C is the concentration of drug in the volume element over which the mass balance is taken, VL is the volume of the tube, and vz is the axial velocity of drug. The theory was first applied to the oral absorption of two tripeptide analogues, cefaclor (CCL) and cefatrizine (CZN), which degrade and dimerize in the intestine. Simulations using the mass balance equations, the experimental absorption parameters, and the literature stability rate constants yielded a mean estimated extent of CCL (250-mg dose) and CZN (1000-mg dose) absorption of 89 and 51%, respectively, which was similar to the mean extent of absorption reported in humans (90 and 50%). It was proposed previously that 15% of the CCL dose spontaneously degraded systematically; however, our simulations suggest that significant CCL degradation occurs (8 to 17%) presystemically in the intestinal lumen.(ABSTRACT TRUNCATED AT 250 WORDS).

Mass balance assessment using GPS

NASA Technical Reports Server (NTRS)

Hulbe, Christina L.

1993-01-01

Mass balance is an integral part of any comprehensive glaciological investigation. Unfortunately, it is hard to determine at remote locations where there is no fixed reference. The Global Positioning System (GPS) offers a solution. Simultaneous GPS observations at a known location and the remote field site, processed differentially, will accurately position the camp site. From there, a monument planted in the firn atop the ice can also be accurately positioned. Change in the monument's vertical position is a direct indicator of ice thickness change. Because the monument is not connected to the ice, its motion is due to both mass balance change and to the settling of firn as it densifies into ice. Observations of relative position change between the monument and anchors at various depths within the firn are used to remove the settling effect. An experiment to test this method has begun at Byrd Station on the West Antarctic Ice Sheet and the first epoch of observations was made. Analysis indicates that positioning errors will be very small. It appears likely that the largest errors involved with this technique will arise from ancillary data needed to determine firn settling.

Miniature Piezoelectric Macro-Mass Balance

NASA Technical Reports Server (NTRS)

Sherrit, Stewart; Trebi-Ollennu, Ashitey; Bonitz, Robert G.; Bar-Cohen, Yoseph

2010-01-01

Mass balances usually use a strain gauge that requires an impedance measurement and is susceptible to noise and thermal drift. A piezoelectric balance can be used to measure mass directly by monitoring the voltage developed across the piezoelectric balance, which is linear with weight or it can be used in resonance to produce a frequency change proportional to the mass change (see figure). The piezoelectric actuator/balance is swept in frequency through its fundamental resonance. If a small mass is added to the balance, the resonance frequency shifts down in proportion to the mass. By monitoring the frequency shift, the mass can be determined. This design allows for two independent measurements of mass. Additionally, more than one sample can be verified because this invention allows for each sample to be transported away from the measuring device upon completion of the measurement, if required. A piezoelectric actuator, or many piezoelectric actuators, was placed between the collection plate of the sampling system and the support structure. As the sample mass is added to the plate, the piezoelectrics are stressed, causing them to produce a voltage that is proportional to the mass and acceleration. In addition, a change in mass delta m produces a change in the resonance frequency with delta f proportional to delta m. In a microgravity environment, the spacecraft could be accelerated to produce a force on the piezoelectric actuator that would produce a voltage proportional to the mass and acceleration. Alternatively, the acceleration could be used to force the mass on the plate, and the inertial effects of the mass on the plate would produce a shift in the resonance frequency with the change in frequency related to the mass change. Three prototypes of the mass balance mechanism were developed. These macro-mass balances each consist of a solid base and an APA 60 Cedrat flextensional piezoelectric actuator supporting a measuring plate. A similar structure with 3 APA 120 Cedrat flextensional piezoelectric actuators spaced equidistantly at 120 degrees supporting the plate and a softer macro balance with an APA 150 actuator/sensor were developed. These flextensional actuators were chosen because they increase the sensitivity of the actuator to stress, allow the piezoelectric to be pre-stressed, and the piezoelectric element is a stacked multilayer actuator, which has a considerably lower input impedance than a monolithic element that allows for common instruments (e.g., input impedance of 10 megohms) to measure the voltage without rapidly discharging the charge/voltage on the piezoelectric actuator.

Elevation and mass change of the Echaurren Norte Glacier (Central Andes, Chile) from 1955 to 2015.

NASA Astrophysics Data System (ADS)

Farías, David; Vivero, Sebastián; Casassa, Gino; Seehaus, Thorsten; Braun, Matthias H.

2017-04-01

The Echaurren Norte Glacier (33°34'S 70°07'W) is a small mountain glacier located at the upper Maipo basin, approximately 80 km to Santiago de Chile. The glacier has the longest surface mass balance record in South America (1975 to 2016). The measurements are carried out by DGA (water directory of Chile) using the direct glaciological method. The surface mass balance show continuous negative values, but exceptional positive mass balances were identified during ENSO periods. The aim of our study is complement the in-situ observations on Echaurren Norte Glacier with the geodetic mass balance measurements for the period 1955 to 2015. Our database comprises digital elevation models (DEM) from historical cartography based on aerial photographs (1955), SRTM (2000) and Lidar data. In addition, we mapped changes in glacier extent using aerial photography and multi-mission satellite data. TanDEM-X (2012-2015) and SRTM data will be used to investigate surrounding glaciers that have not such extensive and detailed coverage as Echaurren Norte Glacier. The aerial photographs from 1955 were scanned from the original negative using a photogrammetric scanner and processed on a digital photogrammetric workstation (DPW) and georeferenced with the aid of GCPs derived from the Lidar dataset. The TanDEM-X data was processed using differential interferometry using SRTM C-band DEM as reference. Differences resulting from X- and C-band penetration are considered comparing X- and C-band SRTM data. All DEMs were laterally and vertically co-registered to each other. Error assessment was done over stable ground. Our preliminary results indicate an elevation change of -42.2 m ± 4 m (1955-2015) for Echaurren Norte Glacier. The estimated averaged annual mass balance is -0.59 m water equivalent for the period 1955-2015 using a density of 0.85 kg/cm3 for volume to mass conversion. Significant changes of the surface cover were identified, with a considerable increase of the debris cover, in particular in the medial zone of the glacier with a layer approximately 0.35 m of thickness (2009-2015).

A MASS BALANCE OF SURFACE WATER GENOTOXICITY IN PROVIDENCE RIVER (RHODE ISLAND USA)

EPA Science Inventory

White and Rasmussen (Mutation Res. 410:223-236) used a mass balance approach to demonstrate that over 85% of the total genotoxic loading to the St. Lawrence River at Montreal is non-industrial. To validate the mass balance approach and investigate the sources of genotoxins in sur...

Surface Mass Balance of the Greenland Ice Sheet Derived from Paleoclimate Reanalysis

NASA Astrophysics Data System (ADS)

Badgeley, J.; Steig, E. J.; Hakim, G. J.; Anderson, J.; Tardif, R.

2017-12-01

Modeling past ice-sheet behavior requires independent knowledge of past surface mass balance. Though models provide useful insight into ice-sheet response to climate forcing, if past climate is unknown, then ascertaining the rate and extent of past ice-sheet change is limited to geological and geophysical constraints. We use a novel data-assimilation framework developed under the Last Millennium Reanalysis Project (Hakim et al., 2016) to reconstruct past climate over ice sheets with the intent of creating an independent surface mass balance record for paleo ice-sheet modeling. Paleoclimate data assimilation combines the physics of climate models and the time series evidence of proxy records in an offline, ensemble-based approach. This framework allows for the assimilation of numerous proxy records and archive types while maintaining spatial consistency with known climate dynamics and physics captured by the models. In our reconstruction, we use the Community Climate System Model version 4, CMIP5 last millennium simulation (Taylor et al., 2012; Landrum et al., 2013) and a nearly complete database of ice core oxygen isotope records to reconstruct Holocene surface temperature and precipitation over the Greenland Ice Sheet on a decadal timescale. By applying a seasonality to this reconstruction (from the TraCE-21ka simulation; Liu et al., 2009), our reanalysis can be used in seasonally-based surface mass balance models. Here we discuss the methods behind our reanalysis and the performance of our reconstruction through prediction of unassimilated proxy records and comparison to paleoclimate reconstructions and reanalysis products.

Life cycle inventory and mass-balance of municipal food waste management systems: Decision support methods beyond the waste hierarchy.

PubMed

Edwards, Joel; Othman, Maazuza; Crossin, Enda; Burn, Stewart

2017-11-01

When assessing the environmental and human health impact of a municipal food waste (FW) management system waste managers typically rely on the principles of the waste hierarchy; using metrics such as the mass or rate of waste that is 'prepared for recycling,' 'recovered for energy,' or 'sent to landfill.' These metrics measure the collection and sorting efficiency of a waste system but are incapable of determining the efficiency of a system to turn waste into a valuable resource. In this study a life cycle approach was employed using a system boundary that includes the entire waste service provision from collection to safe end-use or disposal. A life cycle inventory of seven waste management systems was calculated, including the first service wide inventory of FW management through kitchen in-sink disposal (food waste disposer). Results describe the mass, energy and water balance of each system along with key emissions profile. It was demonstrated that the energy balance can differ significantly from its' energy generation, exemplified by mechanical biological treatment, which was the best system for generating energy from waste but only 5 th best for net-energy generation. Furthermore, the energy balance of kitchen in-sink disposal was shown to be reduced because 31% of volatile solids were lost in pre-treatment. The study also confirmed that higher FW landfill diversion rates were critical for reducing many harmful emissions to air and water. Although, mass-balance analysis showed that the alternative end-use of the FW material may still contain high impact pollutants. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Fluctuations of a Temperate Mountain Glacier in Response to Climate Change

NASA Astrophysics Data System (ADS)

Bachmann, M.; Bidlake, W.

2012-12-01

Glacier mass balance is a fundamental parameter for understanding and predicting the evolution of glaciers on the landscape in response to climate change. The USGS Ice and Climate Project (ICP) continues to extend the longest-running USGS benchmark glacier mass-balance record at South Cascade Glacier, Washington. Due to the importance of South Cascade Glacier data sets for glaciological and climate research, ICP is releasing decades-old previously unpublished glacier surface and bed maps, mass balance data at individual sites, ice velocity data, and an updated ice inventory for the surrounding basin. The complete record includes a pre-Industrial Revolution reconstruction of the glacier and seasonal mass balance measurements for the past 54 years (1958-2012). Since 2000, the glacier has experienced four of the five most negative summer balances and two of the largest positive accumulation years, indicating that the glacier is continuing to respond to recent warming and precipitation changes. Recently, ICP has developed a temperature-index glacier melt model that extrapolates daily accumulation and melt rates from intermittent field observations based on regional meteorological data, and an expert system for mass balance that captures the strengths of both measurement and modeling for assessing mass balance. The models have been successfully calibrated at South Cascade Glacier, where ample observations are available, but are designed to be used with as few or as many glaciological field data as are available for a given ice mass.

Linear regression analysis of emissions factors when firing fossil fuels and biofuels in a commercial water-tube boiler

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharon Falcone Miller; Bruce G. Miller

2007-12-15

This paper compares the emissions factors for a suite of liquid biofuels (three animal fats, waste restaurant grease, pressed soybean oil, and a biodiesel produced from soybean oil) and four fossil fuels (i.e., natural gas, No. 2 fuel oil, No. 6 fuel oil, and pulverized coal) in Penn State's commercial water-tube boiler to assess their viability as fuels for green heat applications. The data were broken into two subsets, i.e., fossil fuels and biofuels. The regression model for the liquid biofuels (as a subset) did not perform well for all of the gases. In addition, the coefficient in the modelsmore » showed the EPA method underestimating CO and NOx emissions. No relation could be studied for SO{sub 2} for the liquid biofuels as they contain no sulfur; however, the model showed a good relationship between the two methods for SO{sub 2} in the fossil fuels. AP-42 emissions factors for the fossil fuels were also compared to the mass balance emissions factors and EPA CFR Title 40 emissions factors. Overall, the AP-42 emissions factors for the fossil fuels did not compare well with the mass balance emissions factors or the EPA CFR Title 40 emissions factors. Regression analysis of the AP-42, EPA, and mass balance emissions factors for the fossil fuels showed a significant relationship only for CO{sub 2} and SO{sub 2}. However, the regression models underestimate the SO{sub 2} emissions by 33%. These tests illustrate the importance in performing material balances around boilers to obtain the most accurate emissions levels, especially when dealing with biofuels. The EPA emissions factors were very good at predicting the mass balance emissions factors for the fossil fuels and to a lesser degree the biofuels. While the AP-42 emissions factors and EPA CFR Title 40 emissions factors are easier to perform, especially in large, full-scale systems, this study illustrated the shortcomings of estimation techniques. 23 refs., 3 figs., 8 tabs.« less

Targeted Quantitation of Proteins by Mass Spectrometry

PubMed Central

2013-01-01

Quantitative measurement of proteins is one of the most fundamental analytical tasks in a biochemistry laboratory, but widely used immunochemical methods often have limited specificity and high measurement variation. In this review, we discuss applications of multiple-reaction monitoring (MRM) mass spectrometry, which allows sensitive, precise quantitative analyses of peptides and the proteins from which they are derived. Systematic development of MRM assays is permitted by databases of peptide mass spectra and sequences, software tools for analysis design and data analysis, and rapid evolution of tandem mass spectrometer technology. Key advantages of MRM assays are the ability to target specific peptide sequences, including variants and modified forms, and the capacity for multiplexing that allows analysis of dozens to hundreds of peptides. Different quantitative standardization methods provide options that balance precision, sensitivity, and assay cost. Targeted protein quantitation by MRM and related mass spectrometry methods can advance biochemistry by transforming approaches to protein measurement. PMID:23517332

Targeted quantitation of proteins by mass spectrometry.

PubMed

Liebler, Daniel C; Zimmerman, Lisa J

2013-06-04

Quantitative measurement of proteins is one of the most fundamental analytical tasks in a biochemistry laboratory, but widely used immunochemical methods often have limited specificity and high measurement variation. In this review, we discuss applications of multiple-reaction monitoring (MRM) mass spectrometry, which allows sensitive, precise quantitative analyses of peptides and the proteins from which they are derived. Systematic development of MRM assays is permitted by databases of peptide mass spectra and sequences, software tools for analysis design and data analysis, and rapid evolution of tandem mass spectrometer technology. Key advantages of MRM assays are the ability to target specific peptide sequences, including variants and modified forms, and the capacity for multiplexing that allows analysis of dozens to hundreds of peptides. Different quantitative standardization methods provide options that balance precision, sensitivity, and assay cost. Targeted protein quantitation by MRM and related mass spectrometry methods can advance biochemistry by transforming approaches to protein measurement.

How Well do we Know Near-Surface Density When Determining Mass Balance by the Geodetic Method?

NASA Astrophysics Data System (ADS)

Kuhn, M. H.; Matzi, E.

2005-12-01

From a data set of firn pits in the accumulation area of Hintereisferner in the years 1964 - 2002 the behavior of density and water equivalent was analyzed with a view to estimating the potential errors in the application of the geodetic method. Since annual specific balance ranged from 100 to 3300 mm w.e. the profiles were scaled to total depth. For the uppermost 10% of the annual deposit at a typical location the 1964-2002 mean density would be 350 kg/m-3 with a standard deviation of 110 kg/m-3; for the 10% layer at the base of the annual snowpack the respective figures are 510 +- 30 kg/m-3. The normalized long term means of an ensemble of 9 pits ranged from 310 to 380 kg/m-3 in the top layer and from 510 to 540 kg/m-3 in the bottom layer. When one outlier is removed the the range in the bottom layer reduces to 525 to 540 kg/m-3. This small local variance encourages the use of the geodetic method. The comparison of elevation models of 1969 and 1997 yields a mass change that agrees very well with the results of the glaciological method provided the volume change is converted to mass with a density of 900 kg/m-3. While this may be true for the entire glacier on long terms, it will fail for individual years in the accumulation area. Possible errors are calculated from the data set emphasizing the role of year to year changes of specific balance and accumulation area ratio.

Estimating ground-water exchange with lakes using water-budget and chemical mass-balance approaches for ten lakes in ridge areas of Polk and Highlands counties, Florida

USGS Publications Warehouse

Sacks, L.A.; Swancar, Amy; Lee, T.M.

1998-01-01

Water budget and chemical mass-balance approaches were used to estimate ground-water exchange with 10 lakes in ridge areas of Polk and Highlands Counties, Florida. At each lake, heads were monitored in the surficial aquifer system and deeper Upper Floridan aquifer, lake stage and rainfall were measured continuously, and lakes and wells were sampled three times between October 1995 and December 1996. The water-budget approach computes net ground-water flow (ground-water inflow minus outflow) as the residual of the monthly waterbudget equation. Net ground-water flow varied seasonally at each of the 10 lakes, and was notably different between lakes, illustrating short-term differences in ground-water fluxes. Monthly patterns in net ground-water flow were related to monthly patterns of other hydrologic variables such as rainfall, ground-water flow patterns, and head differences between the lake and the Upper Floridan aquifer. The chemical mass-balance approach combines the water budget and solute or isotope mass-balance equations, and assumes steady-state conditions. Naturally occurring tracers that were analyzed for include calcium, magnesium, sodium, potassium, chloride, and bromide, the isotopes deuterium and oxygen-18. Chloride and sodium were the most successful solute tracers; however, their concentrations in ground water typically varied spatially, and in places were similar to that in lake water, limiting their sensitivity as tracers. In contrast, the isotopes were more robust tracers because the isotopic composition of ground water was relatively uniform and was distinctly different from the lake water. Groundwater inflow computed using the chemical massbalance method varied significantly between lakes, and ranged from less than 10 to more than 150 inches per year. Both water-budget and chemical mass-balance approaches had limitations, but the multiple lines of evidence gained using both approaches improved the understanding of the role of ground water in the water budget of the lakes.

Mapping the Snow Line Altitude for Large Glacier Samples from Multitemporal Landsat Imagery

NASA Astrophysics Data System (ADS)

Rastner, P.; Nicholson, L. I.; Notarnicola, C.; Prinz, R.; Sailer, R.

2015-12-01

The cryosphere of mountain regions is fastly changing in response to climate change. This is particularly evident in global-scale glacier retreat. Trends in snow cover, however, are more difficult to determine, as annual fluctuations can be very large. Snow is an important parameter in the energy and mass balance of glaciers and the snow line altitude (SLA) at the end of the melting period can be considered as a proxy for the equilibrium line altitude (ELA). By frequently observing the SLA from satellite, region-wide monitoring of glaciers and improved calibration and validation of transient glacier (mass balance) models is possible. In the near future, frequent mapping of the SLA will be strongly facilitated by satellite missions like Sentinel 2A/B, where the same region will be covered every 5 days with 10 m spatial resolution. For this study we have developed an automated tool to derive the SLA for large glacier samples from remote sensing data. The method is first applied in the Ötztal Alps (Austria) where reliable in-situ data of mass balance and ELA are available for several glaciers over a 30-years period. The algorithm currently works with multi-temporal Landsat imagery (1972-2015), digital glacier outlines and a high-quality national DEM. All input datasets are atmospherically and topographically pre-processed before the SLA is automatically retrieved for each glacier. The remote-sensing derived SLA is generally about 200 m lower than the ELA, however, a clear trend in the altitude of the end of summer snow line is detectable (~ 200 m), which is in agreement with the ELA trend observed in the field. After bias correction and conversion to mass balance, the variability in observed mass balance can be well reproduced from the satellite-derived SLA time series. This is promising for application of the approach in other regions.

Preliminary characterization of carbon dioxide transfer in a hollow fiber membrane module as a possible solution for gas-liquid transfer in microgravity conditions

NASA Astrophysics Data System (ADS)

Farges, Bérangère; Duchez, David; Dussap, Claude-Gilles; Cornet, Jean-François

2012-01-01

In microgravity, one of the major challenge encountered in biological life support systems (BLSS) is the gas-liquid transfer with, for instance, the necessity to provide CO2 (carbon source, pH control) and to recover the evolved O2 in photobioreactors used as atmosphere bioregenerative systems.This paper describes first the development of a system enabling the accurate characterization of the mass transfer limiting step for a PTFE membrane module used as a possible efficient solution to the microgravity gas-liquid transfer. This original technical apparatus, together with a technical assessment of membrane permeability to different gases, is associated with a balance model, determining thus completely the CO2 mass transfer problem between phases. First results are given and discussed for the CO2 mass transfer coefficient kLCO obtained in case of absorption experiments at pH 8 using the hollow fiber membrane module. The consistency of the proposed method, based on a gas and liquid phase balances verifying carbon conservation enables a very accurate determination of the kLCO value as a main limiting step of the whole process. Nevertheless, further experiments are still needed to demonstrate that the proposed method could serve in the future as reference method for mass transfer coefficient determination if using membrane modules for BLSS in reduced or microgravity conditions.

Soil carbon changes: comparing flux monitoring and mass balance in a box lysimeter experiment.

Treesearch

S.M. Nay; B.T. Bormann

2000-01-01

Direct measures of soil-surface respiration are needed to evaluate belowground biological processes, forest productivity, and ecosystem responses to global change. Although infra-red gas analyzer {IRGA) methods track reference CO2 flows in lab studies, questions remain for extrapolating IRGA methods to field conditions. We constructed 10 box...

Balancing Scientific Publication and National Security Concerns: Issues for Congress

DTIC Science & Technology

2003-01-10

because of its potential relevance to biological weapons of mass destruction. Whether the current method of only using classification to limit the...terrorist groups in developing weapons of mass destruction. In 2000, researchers at the Co-operative Research Centre for the Biological Control of Pest...development of chemical, biological , or nuclear weapons is not made accessible to terrorists or countries of proliferation concern. The resolution

Bayesian prediction of future ice sheet volume using local approximation Markov chain Monte Carlo methods

NASA Astrophysics Data System (ADS)

Davis, A. D.; Heimbach, P.; Marzouk, Y.

2017-12-01

We develop a Bayesian inverse modeling framework for predicting future ice sheet volume with associated formal uncertainty estimates. Marine ice sheets are drained by fast-flowing ice streams, which we simulate using a flowline model. Flowline models depend on geometric parameters (e.g., basal topography), parameterized physical processes (e.g., calving laws and basal sliding), and climate parameters (e.g., surface mass balance), most of which are unknown or uncertain. Given observations of ice surface velocity and thickness, we define a Bayesian posterior distribution over static parameters, such as basal topography. We also define a parameterized distribution over variable parameters, such as future surface mass balance, which we assume are not informed by the data. Hyperparameters are used to represent climate change scenarios, and sampling their distributions mimics internal variation. For example, a warming climate corresponds to increasing mean surface mass balance but an individual sample may have periods of increasing or decreasing surface mass balance. We characterize the predictive distribution of ice volume by evaluating the flowline model given samples from the posterior distribution and the distribution over variable parameters. Finally, we determine the effect of climate change on future ice sheet volume by investigating how changing the hyperparameters affects the predictive distribution. We use state-of-the-art Bayesian computation to address computational feasibility. Characterizing the posterior distribution (using Markov chain Monte Carlo), sampling the full range of variable parameters and evaluating the predictive model is prohibitively expensive. Furthermore, the required resolution of the inferred basal topography may be very high, which is often challenging for sampling methods. Instead, we leverage regularity in the predictive distribution to build a computationally cheaper surrogate over the low dimensional quantity of interest (future ice sheet volume). Continual surrogate refinement guarantees asymptotic sampling from the predictive distribution. Directly characterizing the predictive distribution in this way allows us to assess the ice sheet's sensitivity to climate variability and change.

Glacier mass-balance fluctuations in the Pacific Northwest and Alaska, USA

USGS Publications Warehouse

Josberger, E.G.; Bidlake, W.R.; March, R.S.; Kennedy, B.W.

2007-01-01

The more than 40 year record of net and seasonal mass-balance records from measurements made by the United States Geological Survey on South Cascade Glacier, Washington, and Wolverine and Gulkana Glaciers, Alaska, shows annual and interannual fluctuations that reflect changes in the controlling climatic conditions at regional and global scales. As the mass-balance record grows in length, it is revealing significant changes in previously described glacier mass-balance behavior, and both inter-glacier and glacier-climate relationships. South Cascade and Wolverine Glaciers are strongly affected by the warm and wet maritime climate of the northeast Pacific Ocean. Their net balances have generally been controlled by winter accumulation, with fluctuations that are strongly related to the Pacific Decadal Oscillation (PDO). Recently, warm dry summers have begun to dominate the net balance of the two maritime glaciers, with a weakening of the correlation between the winter balance fluctuations and the PDO. Non-synchronous periods of positive and negative net balance for each glacier prior to 1989 were followed by a 1989-2004 period of synchronous and almost exclusively negative net balances that averaged -0.8 m for the three glaciers.

Are nonsymmetric balanced configurations of four equal masses virtual or real?

NASA Astrophysics Data System (ADS)

Chenciner, Alain

2017-11-01

Balanced configurations of N point masses are the configurations which, in a Euclidean space of high enough dimension, i. e., up to 2( N - 1), admit a relative equilibrium motion under the Newtonian (or similar) attraction. Central configurations are balanced and it has been proved by Alain Albouy that central configurations of four equal masses necessarily possess a symmetry axis, from which followed a proof that the number of such configurations up to similarity is finite and explicitly describable. It is known that balanced configurations of three equal masses are exactly the isosceles triangles, but it is not known whether balanced configurations of four equal masses must have some symmetry. As balanced configurations come in families, it makes sense to look for possible branches of nonsymmetric balanced configurations bifurcating from the subset of symmetric ones. In the simpler case of a logarithmic potential, the subset of symmetric balanced configurations of four equal masses is easy to describe as well as the bifurcation locus, but there is a grain of salt: expressed in terms of the squared mutual distances, this locus lies almost completely outside the set of true configurations (i. e., generalizations of triangular inequalities are not satisfied) and hence could lead most of the time only to the bifurcation of a branch of virtual nonsymmetric balanced configurations. Nevertheless, a tiny piece of the bifurcation locus lies within the subset of real balanced configurations symmetric with respect to a line and hence has a chance to lead to the bifurcation of real nonsymmetric balanced configurations. This raises the question of the title, a question which, thanks to the explicit description given here, should be solvable by computer experts even in the Newtonian case. Another interesting question is about the possibility for a bifurcating branch of virtual nonsymmetric balanced configurations to come back to the domain of true configurations.

Assessing streamflow sensitivity to variations in glacier mass balance

USGS Publications Warehouse

O'Neel, Shad; Hood, Eran; Arendt, Anthony; Sass, Louis

2014-01-01

The purpose of this paper is to evaluate relationships among seasonal and annual glacier mass balances, glacier runoff and streamflow in two glacierized basins in different climate settings. We use long-term glacier mass balance and streamflow datasets from the United States Geological Survey (USGS) Alaska Benchmark Glacier Program to compare and contrast glacier-streamflow interactions in a maritime climate (Wolverine Glacier) with those in a continental climate (Gulkana Glacier). Our overall goal is to improve our understanding of how glacier mass balance processes impact streamflow, ultimately improving our conceptual understanding of the future evolution of glacier runoff in continental and maritime climates.

A 1 kg Mass Comparator Using Flexure-Strip Suspensions: Preliminary Results

NASA Astrophysics Data System (ADS)

Quinn, T. J.; Speake, C. C.; Davis, R. S.

1986-01-01

This paper describes the design and construction of a novel form of equal-arm balance. The balance has been designed to study the performance of flexure strips for use as pivots in a 1 kg mass comparator working at the highest accuracy. The beam of the balance is servo controlled using optical detection of angular position and electromagnetic control. Small mass differences are measured in terms of the differences in the servo currents required to reproduce the same position of the beam. Preliminary results using this prototype balance indicate that an accuracy in mass comparison of about 5 parts in 1010 can be achieved.

Estimates of Ice Sheet Mass Balance from Satellite Altimetry: Past and Future

NASA Technical Reports Server (NTRS)

Zwally, H. Jay; Zukor, Dorothy J. (Technical Monitor)

2001-01-01

A major uncertainty in predicting sea level rise is the sensitivity of ice sheet mass balance to climate change, as well as the uncertainty in present mass balance. Since the annual water exchange is about 8 mm of global sea level equivalent, the 20% uncertainty in current mass balance corresponds to 1.6 mm/yr in sea level change. Furthermore, estimates of the sensitivity of the mass balance to temperature change range from perhaps as much as - 10% to + 10% per K. A principal purpose of obtaining ice sheet elevation changes from satellite altimetry has been estimation of the current ice sheet mass balance. Limited information on ice sheet elevation change and their implications about mass balance have been reported by several investigators from radar altimetry (Seasat, Geosat, ERS-1&2). Analysis of ERS-1&2 data over Greenland for 7 years from 1992 to 1999 shows mixed patterns of ice elevation increases and decreases that are significant in terms of regional-scale mass balances. Observed seasonal and interannual variations in ice surface elevation are larger than previously expected because of seasonal and interannUal variations in precipitation, melting, and firn compaction. In the accumulation zone, the variations in firn compaction are modeled as a function of temperature leaving variations in precipitation and the mass balance trend. Significant interannual variations in elevation in some locations, in particular the difference in trends from 1992 to 1995 compared to 1995 to 1999, can be explained by changes in precipitation over Greenland. Over the 7 years, trends in elevation are mostly positive at higher elevations and negative at lower elevations. In addition, trends for the winter seasons (from a trend analysis through the average winter elevations) are more positive than the corresponding trends for the summer. At lower elevations, the 7-year trends in some locations are strongly negative for summer and near zero or slightly positive for winter. These observations also demonstrate the potential for relating the variability in mass balance to changes in precipitation, temperature, and melting. Beginning in January 2002, NASA's ICESat laser altimeter mission will provide significantly better elevation accuracy and spatial coverage to 86E latitude and to the margins of the ice sheets.

Use of a new ultra-long-range terrestrial LiDAR system to monitor the mass balance of very small glaciers in the Swiss Alps

NASA Astrophysics Data System (ADS)

Fischer, M.; Huss, M.; Hoelzle, M.

2015-12-01

Measuring glacier mass balance is important as it directly reflects the climatic forcing on the glacier surface. Today, repeated comparison of digital elevation models (DEMs) is a popular and widely used approach to derive surface elevation, volume and mass changes for a large number of glaciers. In high-mountain environments, airborne laser scanning (ALS) techniques currently provide the most accurate and highest resolution DEMs on the catchment scale, allowing the computation of glacier changes on an annual or even semi-annual basis. For monitoring individual glaciers though, terrestrial laser scanning (TLS) is easier and more cost-efficiently applied on the seasonal timescale compared to ALS. Since most recently, the application of the latest generation of ultra-long-range near infrared TLS systems allows the acquisition of surface elevation information over snow and ice of unprecedented quality and over larger zones than with previous near infrared TLS devices. Although very small glaciers represent the majority in number in most mountain ranges on Earth, their response to climatic changes is still not fully understood and field measurements are sparse. Therefore, a programme was set up in 2012 to monitor both the seasonal and annual surface mass balance of six very small glaciers across the Swiss Alps using the direct glaciological method. As often nearly the entire surface is visible from one single location, TLS is a highly promising technique to generate repeated high-resolution DEMs as well as to derive seasonal geodetic mass balances of very small ice masses. In this study, we present seasonal surface elevation, volume and geodetic mass changes for five very small glaciers in Switzerland (Glacier de Prapio, Glacier du Sex Rouge, St. Annafirn, Schwarzbachfirn and Pizolgletscher) derived from the comparison of seasonally repeated high-resolution DEMs acquired since autumn 2013 with the new ultra-long-range TLS device Riegl VZ-6000. We show the different processing steps necessary to derive geodetic glacier changes from the raw data (the TLS point clouds), comment on the accuracy of our results and compare them to very dense in-situ measurements, and thus investigate the potential of our approach to circumvent laborious and time consuming glaciological mass balance measurements of very small glaciers.

Forecasting Glacier Evolution and Hindcasting Paleoclimates In Light of Mass Balance Nonlinearities

NASA Astrophysics Data System (ADS)

Malone, A.; Doughty, A. M.; MacAyeal, D. R.

2016-12-01

Glaciers are commonly used barometers of present and past climate change, with their variations often being linked to shifts in the mean climate. Climate variability within a unchanging mean state, however, can produce short term mass balance and glacier length anomalies, complicating this linkage. Also, the mass balance response to this variability can be nonlinear, possibly impacting the longer term state of the glacier. We propose a conceptual model to understand these nonlinearities and quantify their impacts on the longer term mass balance and glacier length. The relationship between mass balance and elevation, i.e. the vertical balance profile (VBP), illuminates these nonlinearities (Figure A). The VBP, given here for a wet tropical glacier, is piecewise, which can lead to different mass balance responses to climate anomalies of similar magnitude but opposite sign. We simulate the mass balance response to climate variability by vertically (temperature anomalies) and horizontally (precipitation anomalies) transposing the VBP for the mean climate (Figure A). The resulting anomalous VBP is the superposition of the two translations. We drive a 1-D flowline model with 10,000 years of anomalous VBPs. The aggregate VBP for the mean climate including variability differs from the VBP for the mean climate excluding variability, having a higher equilibrium line altitude (ELA) and a negative mass balance (Figure B). Accordingly, the glacier retreats, and the equilibrium glacier length for the aggregate VBP is the same as the mean length from the 10,000 year flowline simulation (Figure C). The magnitude of the VBP shift and glacier retreat increases with greater temperature variability and larger discontinuities in the VBP slope. These results highlight the importance of both the climate mean and variability in determining the longer term state of the glacier. Thus, forecasting glacier evolution or hindcasting past climates should also include representation of climate variability.

Water, Ice, and Meteorological Measurements at South Cascade Glacier, Washington, Balance Years 2004 and 2005

USGS Publications Warehouse

Bidlake, William R.; Josberger, Edward G.; Savoca, Mark E.

2007-01-01

Winter snow accumulation and summer snow and ice ablation were measured at South Cascade Glacier, Washington, to estimate glacier mass-balance quantities for balance years 2004 and 2005. The North Cascade Range in the vicinity of South Cascade Glacier accumulated smaller than normal winter snowpacks during water years 2004 and 2005. Correspondingly, the balance years 2004 and 2005 maximum winter snow balances of South Cascade Glacier, 2.08 and 1.97 meters water equivalent, respectively, were smaller than the average of such balances since 1959. The 2004 glacier summer balance (-3.73 meters water equivalent) was the eleventh most negative during 1959 to 2005 and the 2005 glacier summer balance (-4.42 meters water equivalent) was the third most negative. The relatively small winter snow balances and unusually negative summer balances of 2004 and 2005 led to an overall loss of glacier mass. The 2004 and 2005 glacier net balances, -1.65 and -2.45 meters water equivalent, respectively, were the seventh and second most negative during 1953 to 2005. For both balance years, the accumulation area ratio was less than 0.05 and the equilibrium line altitude was higher than the glacier. The unusually negative 2004 and 2005 glacier net balances, combined with a negative balance previously reported for 2003, resulted in a cumulative 3-year net balance of -6.20 meters water equivalent. No equal or greater 3-year mass loss has occurred previously during the more than 4 decades of U.S. Geological Survey mass-balance measurements at South Cascade Glacier. Accompanying the glacier mass losses were retreat of the terminus and reduction of total glacier area. The terminus retreated at a rate of about 17 meters per year during balance year 2004 and 15 meters per year during balance year 2005. Glacier area near the end of balance years 2004 and 2005 was 1.82 and 1.75 square kilometers, respectively. Runoff from the basin containing the glacier and from an adjacent nonglacierized basin was gaged during all or parts of water years 2004 and 2005. Air temperature, wind speed, precipitation, and incoming solar radiation were measured at selected locations on and near the glacier.

Recent Changes in Ices Mass Balance of the Amundsen Sea Sector

NASA Astrophysics Data System (ADS)

Sutterley, T. C.; Velicogna, I.; Rignot, E. J.; Mouginot, J.; Flament, T.; van den Broeke, M. R.; van Wessem, M.; Reijmer, C.

2014-12-01

The glaciers flowing into the Amundsen Sea Embayment (ASE) sector of West Antarctica were confirmed in the Ice Sheet Mass Balance Inter-comparison Exercise (IMBIE) to be the dominant contributors to the current Antarctic ice mass loss, and recently recognized to be undergoing marine ice sheet instability. Here, we investigate their regional ice mass balance using a time series of satellite and airborne data combined with model output products from the Regional Atmospheric and Climate Model (RACMO). Our dataset includes laser altimetry from NASA's ICESat-1 satellite mission and from Operation IceBridge (OIB) airborne surveys, satellite radar altimetry data from ESA's Envisat mission, time-variable gravity data from NASA/DLR's GRACE mission, surface mass balance products from RACMO, ice velocity from a combination of international synthetic aperture radar satellites and ice thickness data from OIB. We find a record of ice mass balance for the ASE where all the analyzed techniques agree remarkably in magnitude and temporal variability. The mass loss of the region has been increasing continuously since 1992, with no indication of a slow down. The mass loss during the common period averaged 91 Gt/yr and accelerated 20 Gt/yr2. In 1992-2013, the ASE contributed 4.5 mm global sea level rise. Overall, our results demonstrate the synergy of multiple analysis techniques for examining Antarctic Ice Sheet mass balance at the regional scale. This work was performed at UCI and JPL under a contract with NASA.

The response of glaciers to climate change

NASA Astrophysics Data System (ADS)

Klok, Elisabeth Jantina

2003-12-01

The research described in this thesis addresses two aspects of the response of glaciers to climate change. The first aspect deals with the physical processes that govern the interaction between glaciers and climate change and was treated by (1) studying the spatial and temporal variation of the glacier albedo from satellite images, (2) investigating the spatial distribution of the surface energy and mass balance of a glacier, and (3) investigating the sensitivity of the mass balance to climate change. All of these studies are focused on Morteratschgletscher in Switzerland. The second aspect is the climatic interpretation of glacier length fluctuations. This was studied by developing a model that calculates historical mass balance records from global glacier length fluctuations. To increase our understanding of the variations in glacier albedo, we derived surface albedos from 12 Landsat images. This constituted a stringent test for the retrieval methodology applied because Morteratschgletscher is very steep and rugged, which strongly influences the satellite signal. We aimed to retrieve surface albedos while taking into account all important processes that influence the relationship between the satellite signal and the surface albedo, e.g. the topographic effects on incoming solar radiation, and the anisotropic nature of the reflection pattern of ice and snow surfaces. We then analysed the spatial and temporal pattern of the surface albedo. We developed a two-dimensional mass balance model based on the surface energy balance to study the spatial distribution of the energy and mass balance fluxes of Morteratschgletscher. Meteorological data from weather stations in the vicinity of Morteratschgletscher serve as input for the model. We corrected incoming solar radiation for shading, aspect, slope, reflection from surrounding slopes, and obstruction of the sky. Ignoring these effects results in an increase in solar radiation of 37%, causing a decrease in the mass balance of 0.34 m w.e. We modelled the mass balance for 1999 and 2000 and analysed the spatial distribution. We then ran the model for a period of 23 years and calculated the mass balance sensitivity to climate change by perturbing air temperature and precipitation. The mass balance sensitivity to temperature and precipitation are ˜0.59 m w.e. a-1 K-1 and 0.17 m w.e. a-1 per 10 percent respectively. We also used three other albedo parameterisations to calculate the mass balance sensitivity since albedo parameterisations are often regarded as a main source of error in mass balance models. We concluded that an accurate estimate of the mass balance sensitivity requires a parameterisation that captures the process of a decreasing snow albedo when a snow pack gets older or thinner. To extract a climate signal from worldwide glacier length fluctuations, we developed a simple model. The climate signal is represented as a reconstruction of the mass balance and the equilibrium line altitude (ELA). The model was tested on seventeen European glacier length records and then applied to nineteen glacier length records from different parts of the world. Between 1910 and 1959, the average increase in the reconstructed ELAs is 33 m. This implies that during the first half of the twentieth century, the climate was warmer or drier than before. The reconstructed ELAs decrease to lower elevations after 1960 and up till 1980, when most of the reconstructions end. The results can be translated into a global temperature increase of about 0.8 K for the period 1910-1959

Overview of Ice-Sheet Mass Balance and Dynamics from ICESat Measurements

NASA Technical Reports Server (NTRS)

Zwally, H. Jay

2010-01-01

The primary purpose of the ICESat mission was to determine the present-day mass balance of the Greenland and Antarctic ice sheets, identify changes that may be occurring in the surface-mass flux and ice dynamics, and estimate their contributions to global sea-level rise. Although ICESat's three lasers were planned to make continuous measurements for 3 to 5 years, the mission was re-planned to operate in 33-day campaigns 2 to 3 times each year following failure of the first laser after 36 days. Seventeen campaigns were conducted with the last one in the Fall of 2009. Mass balance maps derived from measured ice-sheet elevation changes show that the mass loss from Greenland has increased significantly to about 170 Gt/yr for 2003 to 2007 from a state of near balance in the 1990's. Increased losses (189 Gt/yr) from melting and dynamic thinning are over seven times larger'than increased gains (25 gt/yr) from precipitation. Parts of the West Antarctic ice sheet and the Antarctic Peninsula are losing mass at an increasing rate, but other parts of West Antarctica and the East Antarctic ice sheet are gaining mass at an increasing rate. Increased losses of 35 Gt/yr in Pine Island, Thwaites-Smith, and Marie-Bryd.Coast are more than balanced by gains in base of Peninsula and ice stream C, D, & E systems. From the 1992-2002 to 2003-2007 period, the overall mass balance for Antarctica changed from a loss of about 60 Gt/yr to near balance or slightly positive.

Mass Balance Reconstruction and Volumetric change of Stok Glaicer , Ladak Region, Western Himalyas,India (1969-2015)

NASA Astrophysics Data System (ADS)

Mohd, S.; AL, R.

2017-12-01

Understanding mass balance and volumetric change of glaciers are extremely important in areas where the majority of the population depends on cryospheric sources for the livelihood. Ladakh is one of the coldest and the aridest region of India. The majority of the population live in mountain pockets where the only source of water is snow and glacier melt for agriculture and domestic use. Stok village catchment (52 km2) has seven very small glaciers with an area ranging between 0.2-1.05 km2 at an elevation above 5300m a.s.l (GSI 2009). These glaciers contribute to a stream feeding Stok village of 274 ( 1469 individuals) households and a portion of Chuchot village before joining the Indus River. Ironically very limited studies have been carried out so far in this region, making it even more urgent to monitor the health of the glaciers in this region. With the changing climate, booming of the tourism industry and scarcity of water resources during the spring season, there is a shift in the livelihood of the region towards other option leading to a negative impact on the environment and over exploitation of natural resources. In this study we present analysis of measured annual mass balances for the period 2015-2017 and reconstruction of annual mass balances since 1969 to 2015 of Stok glacier located on the north eastern slope of Zanskar range in Ladakh region of western Himalayas. Direct glaciological methods were used to obtain annual mass balance for 2015-2017 and for reconstruction of annual mass balances, Classical Temperature Index model were used with the help of meteorological data from Indian Meteorological Department. The data gaps were filled with the help of several modelled datasets viz. HAR (High Asia Reanalysis), REMO, and Climate Research Unit (CRU) TS2.1 dataset. We also present catchment wide change in volume of the glaciers since 1969 to 2015. Declassified satellite images and Landsat images were used to obtain the change in volume of the glacier with the help of already established empirical relationships. Since the region has a large number of such catchments (mountain pockets) therefore understanding one such catchment (e.g. Stok village catchment) will surely help policy making on a larger scale. Acknowledgement: Authors thank UGC UPOE II (project) for the support

Mass balance in the monitoring of pollutants in tidal rivers of the Guanabara Bay, Rio de Janeiro, Brazil.

PubMed

da Silveira, Raquel Pinhão; Rodrigues, Ana Paula de Castro; Santelli, Ricardo Erthal; Cordeiro, Renato Campello; Bidone, Edison Dausacker

2011-10-01

This study addressed the identification and monitoring of pollution sources of terrestrial origin in rivers (domestic sewage and industrial effluents) and critical fluvial segments in highly polluted environments under tidal influence (mixing marine and continental sources) from Guanabara Bay Basin, Rio de Janeiro, Brazil. The mass balance of contaminants was determined in conditions of continuous flow (low tide) during dry season (lower dilution capability). The results allowed the evaluation of the potential of contaminant mass generation by the different river segments and the estimation of their natural and anthropogenic components. The water quality of Iguaçú and Sarapuí Rivers were evaluated for metals and biochemical oxygen demand. The method gave an excellent response, including the possibility of sources identification and contaminated river segments ranking. The approach also offers fast execution and data interpretation, being highly efficient.

Thermal Behaviors and Their Correlations of Mg(BH4)2-Contained Explosives

NASA Astrophysics Data System (ADS)

Yue, Yue; Chen, Liping; Peng, Jinhua

2018-01-01

In order to explore the effect of metal hydride on energetic materials' thermal behaviors and their correlations, we studied the heats of combustion and detonation of RDX, TNT, and Mg(BH4)2-containing explosives both theoretically and experimentally. The results showed that Mg(BH4)2 can significantly improve the energy of explosive. As the mass fraction of Mg(BH4)2 increases, the combustion heat of composite explosives increases gradually, while the combustion efficiency decreases. When its mass fraction is about 30%, the theoretical heats of detonation of RDX/Mg(BH4)2 and TNT/Mg(BH4)2 reach maximum, which are 7418.47 and 7032.46 kJ/kg, respectively. When we compared the errors between calculation and experimental values, we found that L-C method is more accurate in calculating oxygen-enriched and oxygen-balanced explosives, and that minimum free energy method is more suitable for seriously negative oxygen-balanced explosive. For single explosive, there are three kinds of relationships between heat of combustion and detonation according to the oxygen balance. For Mg(BH4)2-containing explosives, the relationship is in accordance with Boltzmann function.

Comparison of SOC estimates and uncertainties from aerosol chemical composition and gas phase data in Atlanta

NASA Astrophysics Data System (ADS)

Pachon, Jorge E.; Balachandran, Sivaraman; Hu, Yongtao; Weber, Rodney J.; Mulholland, James A.; Russell, Armistead G.

2010-10-01

In the Southeastern US, organic carbon (OC) comprises about 30% of the PM 2.5 mass. A large fraction of OC is estimated to be of secondary origin. Long-term estimates of SOC and uncertainties are necessary in the evaluation of air quality policy effectiveness and epidemiologic studies. Four methods to estimate secondary organic carbon (SOC) and respective uncertainties are compared utilizing PM 2.5 chemical composition and gas phase data available in Atlanta from 1999 to 2007. The elemental carbon (EC) tracer and the regression methods, which rely on the use of tracer species of primary and secondary OC formation, provided intermediate estimates of SOC as 30% of OC. The other two methods, chemical mass balance (CMB) and positive matrix factorization (PMF) solve mass balance equations to estimate primary and secondary fractions based on source profiles and statistically-derived common factors, respectively. CMB had the highest estimate of SOC (46% of OC) while PMF led to the lowest (26% of OC). The comparison of SOC uncertainties, estimated based on propagation of errors, led to the regression method having the lowest uncertainty among the four methods. We compared the estimates with the water soluble fraction of the OC, which has been suggested as a surrogate of SOC when biomass burning is negligible, and found a similar trend with SOC estimates from the regression method. The regression method also showed the strongest correlation with daily SOC estimates from CMB using molecular markers. The regression method shows advantages over the other methods in the calculation of a long-term series of SOC estimates.

Groundwater inflow measurements in wetland systems

USGS Publications Warehouse

Hunt, Randy J.; Krabbenhoft, David P.; Anderson, Mary P.

1996-01-01

Our current understanding of wetlands is insufficient to assess the effects of past and future wetland loss. While knowledge of wetland hydrology is crucial, groundwater flows are often neglected or uncertain. In this paper, groundwater inflows were estimated in wetlands in southwestern Wisconsin using traditional Darcy's law calculations and three independent methods that included (1) stable isotope mass balances, (2) temperature profile modeling, and (3) numerical water balance modeling techniques. Inflows calculated using Darcy's law were lower than inflows estimated using the other approaches and ranged from 0.02 to 0.3 cm/d. Estimates obtained using the other methods generally were higher (0.1 to 1.1 cm/d) and showed similar spatial trends. An areal map of groundwater flux generated by the water balance model demonstrated that areas of both recharge and discharge exist in what is considered a regional discharge area. While each method has strengths and weaknesses, the use of more than one method can reduce uncertainty in the estimates.

Diagnosing the decline in climatic mass balance of glaciers in Svalbard over 1957-2014

NASA Astrophysics Data System (ADS)

Ims Østby, Torbjørn; Vikhamar Schuler, Thomas; Ove Hagen, Jon; Hock, Regine; Kohler, Jack; Reijmer, Carleen H.

2017-01-01

Estimating the long-term mass balance of the high-Arctic Svalbard archipelago is difficult due to the incomplete geodetic and direct glaciological measurements, both in space and time. To close these gaps, we use a coupled surface energy balance and snow pack model to analyse the mass changes of all Svalbard glaciers for the period 1957-2014. The model is forced by ERA-40 and ERA-Interim reanalysis data, downscaled to 1 km resolution. The model is validated using snow/firn temperature and density measurements, mass balance from stakes and ice cores, meteorological measurements, snow depths from radar profiles and remotely sensed surface albedo and skin temperatures. Overall model performance is good, but it varies regionally. Over the entire period the model yields a climatic mass balance of 8.2 cm w. e. yr-1, which corresponds to a mass input of 175 Gt. Climatic mass balance has a linear trend of -1.4 ± 0.4 cm w. e. yr-2 with a shift from a positive to a negative regime around 1980. Modelled mass balance exhibits large interannual variability, which is controlled by summer temperatures and further amplified by the albedo feedback. For the recent period 2004-2013 climatic mass balance was -21 cm w. e. yr-1, and accounting for frontal ablation estimated by Błaszczyk et al.(2009) yields a total Svalbard mass balance of -39 cm w. e. yr-1 for this 10-year period. In terms of eustatic sea level, this corresponds to a rise of 0.037 mm yr-1. Refreezing of water in snow and firn is substantial at 22 cm w. e. yr-1 or 26 % of total annual accumulation. However, as warming leads to reduced firn area over the period, refreezing decreases both absolutely and relative to the total accumulation. Negative mass balance and elevated equilibrium line altitudes (ELAs) resulted in massive reduction of the thick (> 2 m) firn extent and an increase in the superimposed ice, thin (< 2 m) firn and bare ice extents. Atmospheric warming also leads to a marked change in the thermal regime, with cooling of the glacier mid-elevation and warming in the ablation zone and upper firn areas. On the long-term, by removing the thermal barrier, this warming has implications for the vertical transfer of surface meltwater through the glacier and down to the base, influencing basal hydrology, sliding and thereby overall glacier motion.

DISCRETE VOLUME-ELEMENT METHOD FOR NETWORK WATER- QUALITY MODELS

EPA Science Inventory

An explicit dynamic water-quality modeling algorithm is developed for tracking dissolved substances in water-distribution networks. The algorithm is based on a mass-balance relation within pipes that considers both advective transport and reaction kinetics. Complete mixing of m...

Skylab water balance error analysis

NASA Technical Reports Server (NTRS)

Leonard, J. I.

1977-01-01

Estimates of the precision of the net water balance were obtained for the entire Skylab preflight and inflight phases as well as for the first two weeks of flight. Quantitative estimates of both total sampling errors and instrumentation errors were obtained. It was shown that measurement error is minimal in comparison to biological variability and little can be gained from improvement in analytical accuracy. In addition, a propagation of error analysis demonstrated that total water balance error could be accounted for almost entirely by the errors associated with body mass changes. Errors due to interaction between terms in the water balance equation (covariances) represented less than 10% of the total error. Overall, the analysis provides evidence that daily measurements of body water changes obtained from the indirect balance technique are reasonable, precise, and relaible. The method is not biased toward net retention or loss.

Sway Area and Velocity Correlated With MobileMat Balance Error Scoring System (BESS) Scores.

PubMed

Caccese, Jaclyn B; Buckley, Thomas A; Kaminski, Thomas W

2016-08-01

The Balance Error Scoring System (BESS) is often used for sport-related concussion balance assessment. However, moderate intratester and intertester reliability may cause low initial sensitivity, suggesting that a more objective balance assessment method is needed. The MobileMat BESS was designed for objective BESS scoring, but the outcome measures must be validated with reliable balance measures. Thus, the purpose of this investigation was to compare MobileMat BESS scores to linear and nonlinear measures of balance. Eighty-eight healthy collegiate student-athletes (age: 20.0 ± 1.4 y, height: 177.7 ± 10.7 cm, mass: 74.8 ± 13.7 kg) completed the MobileMat BESS. MobileMat BESS scores were compared with 95% area, sway velocity, approximate entropy, and sample entropy. MobileMat BESS scores were significantly correlated with 95% area for single-leg (r = .332) and tandem firm (r = .474), and double-leg foam (r = .660); and with sway velocity for single-leg (r = .406) and tandem firm (r = .601), and double-leg (r = .575) and single-leg foam (r = .434). MobileMat BESS scores were not correlated with approximate or sample entropy. MobileMat BESS scores were low to moderately correlated with linear measures, suggesting the ability to identify changes in the center of mass-center of pressure relationship, but not higher-order processing associated with nonlinear measures. These results suggest that the MobileMat BESS may be a clinically-useful tool that provides objective linear balance measures.

Ultraendurance cycling in a hot environment: thirst, fluid consumption, and water balance.

PubMed

Armstrong, Lawrence E; Johnson, Evan C; McKenzie, Amy L; Ellis, Lindsay A; Williamson, Keith H

2015-04-01

The purpose of this field investigation was to identify and clarify factors that may be used by strength and conditioning professionals to help athletes drink adequately but not excessively during endurance exercise. A universal method to accomplish this goal does not exist because the components of water balance (i.e., sweat rate, fluid consumed) are different for each athlete and endurance events differ greatly. Twenty-six male cyclists (mean ± SD; age, 41 ± 8 years; height, 177 ± 7 cm; body mass, 81.85 ± 8.95 kg) completed a summer 164-km road cycling event in 7.0 ± 2.1 hours (range, 4.5-10.4 hours). Thirst ratings, fluid consumed, indices of hydration status, and body water balance (ingested fluid volume - [urine excreted + sweat loss]) were the primary outcome variables. Measurements were taken before the event, at designated aid stations on the course (52, 97, and 136 km), and at the finish line. Body water balance during exercise was not significantly correlated with exercise time on the course, height, body mass, or body mass index. Thirst ratings were not significantly correlated with any variable. We also observed a wide range of total sweat losses (4.9-12.7 L) and total fluid intakes (2.1-10.5 L) during this ultraendurance event. Therefore, we recommend that strength and conditioning professionals develop an individualized drinking plan for each athlete, by calculating sweat rate (milliliter per hour) on the basis of body mass change (in kilograms), during field simulations of competition.

Evaluating Interannual Variability of Accumulation Gradients on the Juneau Icefield

NASA Astrophysics Data System (ADS)

Koncewicz, E.; Bollen, K.; Burkhart, A.; Cabrera, V.; Rovzar, T.; Truax, O.; McNeil, C.; Nicholson, L. I.; O'Neel, S.

2016-12-01

The Juneau Icefield Research Program has collected mass balance data over the last 70 years on the Taku and Lemon Creek glaciers. We analyze data from 2004-2016 to investigate the interannual variability in the accumulation gradients of these two glaciers from ground penetrating radar (GPR), probing, and snow pits. Understanding interannual variability of accumulation gradients on the Juneau Icefield will help us to interpret its long-term mass balance record. The Lemon Creek Glacier is a small valley glacier on the southwest edge of the Icefield. GPR data was collected over the glacier surface in March 2015 and 2016. In July of 2014 and 2016, the accumulation area was probed for snow depth, and two snow pits were dug for snow depth and density. The accumulation gradients resulting from each method are compared between years to assess the interannnual variability of the accumulation gradient and the resulting glacier wide mass balance. The Taku Glacier is the largest outlet glacier on the Juneau Icefield. We use three snow pits dug each year along the longitudinal profile of the glacier between 1000m and 1115m, the region that typically reflects the ELA. In 2004, 2005, 2010, 2011, and 2016, snow probing was continued in the central region of the Taku and the resulting gradients are compared to each other and to the gradients derived from the snow pits. We assess the resulting impact on glacier wide mass balance furthering our understanding of the state of these two well-monitored glaciers on the Juneau Icefield.

Complementing approaches to demonstrate chlorinated solvent biodegradation in a complex pollution plume: Mass balance, PCR and compound-specific stable isotope analysis

NASA Astrophysics Data System (ADS)

Courbet, Christelle; Rivière, Agnès; Jeannottat, Simon; Rinaldi, Sandro; Hunkeler, Daniel; Bendjoudi, Hocine; de Marsily, Ghislain

2011-11-01

This work describes the use of different complementing methods (mass balance, polymerase chain reaction assays and compound-specific stable isotope analysis) to demonstrate the existence and effectiveness of biodegradation of chlorinated solvents in an alluvial aquifer. The solvent-contaminated site is an old chemical factory located in an alluvial plain in France. As most of the chlorinated contaminants currently found in the groundwater at this site were produced by local industries at various times in the past, it is not enough to analyze chlorinated solvent concentrations along a flow path to convincingly demonstrate biodegradation. Moreover, only a few data were initially available to characterize the geochemical conditions at this site, which were apparently complex at the source zone due to (i) the presence of a steady oxygen supply to the groundwater by irrigation canal losses and river infiltration and (ii) an alkaline pH higher than 10 due to former underground lime disposal. A demonstration of the existence of biodegradation processes was however required by the regulatory authority within a timeframe that did not allow a full geochemical characterization of such a complex site. Thus a combination of different fast methods was used to obtain a proof of the biodegradation occurrence. First, a mass balance analysis was performed which revealed the existence of a strong natural attenuation process (biodegradation, volatilization or dilution), despite the huge uncertainty on these calculations. Second, a good agreement was found between carbon isotopic measurements and PCR assays (based on 16S RNA gene sequences and functional genes), which clearly indicated reductive dechlorination of different hydrocarbons (Tetrachloroethene—PCE-, Trichloroethene—TCE-, 1,2- cisDichloroethene— cis-1,2-DCE-, 1,2- transDichloroethene— trans-1,2-DCE-, 1,1-Dichloroethene—1,1-DCE-, and Vinyl Chloride—VC) to ethene. According to these carbon isotope measurements, although TCE biodegradation seems to occur only in the upgradient part of the studied zone, DCE and VC dechlorination (originating from the initial TCE dechlorination) occurs along the entire flowpath. TCE reductase was not detected among the Dehalococcoides bacteria identified by quantitative PCR (qPCR), while DCE and VC reductases were present in the majority of the population. Reverse transcriptase PCR assays (rt-PCR) also indicated that bacteria and their DCE and VC reductases were active. Mass balance calculations showed moreover that 1,1-DCE was the predominant DCE isomer produced by TCE dechlorination in the upgradient part of the site. Consequently, coupling rt-PCR assays with isotope measurements removes the uncertainties inherent in a simple mass balance approach, so that when the three methods are used jointly, they allow the identification and quantification of natural biodegradation, even under apparently complex geochemical and hydraulic conditions.

Experimental Determination of Air Density Using a 1 kg Mass Comparator in Vacuum

NASA Astrophysics Data System (ADS)

Gläser, M.; Schwartz, R.; Mecke, M.

1991-01-01

The density of ambient air has been determined by a straightforward experimental method. The apparent masses of two artefacts having about the same mass and surface, but different well-known volumes, have been compared by using a 1 kg balance in vacuum and in air. The differences of apparent masses and volumes yield the air density with a relative uncertainty (1σ) of 5 × 10-5. From measurements made using a third artefact, surface sorption effects caused by the change between vacuum and air conditions gave a coefficient of about 0,2 μg cm-2.

Physical Activity Associated with Prayer Regimes Improves Standing Dynamic Balance of Healthy People

PubMed Central

AlAbdulwahab, Sami Saleh; Kachanathu, Shaji John; Oluseye, Kamaldeen

2014-01-01

[Purpose] Preparing for prayers, practicing religious meditation and performing prayers are believed to stimulate the visual, vestibular and somatosensory systems, which provide the sensory information that influences human balance. The purpose of this study was to determine the effect of the Islamic prayer regime on balance. [Subjects and Methods] Sixty healthy male subjects with a mean age of 31 ± 5 years and a mean body mass index of 27 ± 2 kg/cm2 voluntarily participated in this study. The subjects were divided into two equal groups: one group of subjects who regularly practiced Islamic prayer, and another group of non-practicing subjects. The dynamic balance of individuals in both groups was measured using a Balance Master. [Results] Adult healthy subjects practicing Islamic prayer regimes exhibited statistically significantly better dynamic balance than the non-practicing healthy subjects. [Conclusions] The results of this study support the hypothesis that religious meditation and prayers benefit human physiological function, especially balance. PMID:24409021

Impacts of invasive earthworms on soil mercury cycling: Two mass balance approaches to an earthworm invasion in a northern Minnesota forest

Treesearch

Sona Psarska; Edward A. Nater; Randy Kolka

2016-01-01

Invasive earthworms perturb natural forest ecosystems that initially developed without them, mainly by consuming the forest floor (an organic rich surficial soil horizon) and by mixing the upper parts of the soil. The fate of mercury (Hg) formerly contained in the forest floor is largely unknown. We used two mass balance approaches (simple mass balance and geochemical...

Net mass balance calculations for the Shirase Drainage Basin, east Antarctica, using the mass budget method

NASA Astrophysics Data System (ADS)

Nakamura, Kazuki; Yamanokuchi, Tsutomu; Doi, Koichiro; Shibuya, Kazuo

2016-06-01

We quantify the mass budget of the Shirase drainage basin (SHI), Antarctica, by separately estimating snow accumulation (surface mass balance; SMB) and glacier ice mass discharge (IMD). We estimated the SMB in the SHI, using a regional atmospheric climate model (RACMO2.1). The SMB of the mainstream A flow region was 12.1 ± 1.5 Gt a-1 for an area of 1.985 × 105 km2. Obvious overestimation of the model round the coast, ∼0.5 Gt a-1, was corrected for. For calculating the IMD, we employed a 15-m resolution Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) with a digital elevation model (DEM) to determine the heights at the grounding line (GL), after comparison with the interpolated Bamber DEM grid heights; the results of this are referred to as the measured heights. Ice thickness data at the GL were inferred by using a free-board relationship between the measured height and the ice thickness, and considering the measured firn depth correction (4.2 m with the reference ice density of 910 kg m-3) for the nearby blue-ice area. The total IMD was estimated to be 14.0 ± 1.8 Gt a-1. Semi-empirical firn densification model gives the estimate within 0.1-0.2 Gt a-1 difference. The estimated net mass balance, -1.9 Gt a-1, has a two-σ uncertainty of ±3.3 Gt a-1, and probable melt water discharge strongly suggests negative NMB, although the associated uncertainty is large.

Lake-level frequency analysis for Devils Lake, North Dakota

USGS Publications Warehouse

Wiche, Gregg J.; Vecchia, Aldo V.

1996-01-01

Two approaches were used to estimate future lake-level probabilities for Devils Lake. The first approach is based on an annual lake-volume model, and the second approach is based on a statistical water mass-balance model that generates seasonal lake volumes on the basis of seasonal precipitation, evaporation, and inflow. Autoregressive moving average models were used to model the annual mean lake volume and the difference between the annual maximum lake volume and the annual mean lake volume. Residuals from both models were determined to be uncorrelated with zero mean and constant variance. However, a nonlinear relation between the residuals of the two models was included in the final annual lakevolume model.Because of high autocorrelation in the annual lake levels of Devils Lake, the annual lake-volume model was verified using annual lake-level changes. The annual lake-volume model closely reproduced the statistics of the recorded lake-level changes for 1901-93 except for the skewness coefficient. However, the model output is less skewed than the data indicate because of some unrealistically large lake-level declines. The statistical water mass-balance model requires as inputs seasonal precipitation, evaporation, and inflow data for Devils Lake. Analysis of annual precipitation, evaporation, and inflow data for 1950-93 revealed no significant trends or long-range dependence so the input time series were assumed to be stationary and short-range dependent.Normality transformations were used to approximately maintain the marginal probability distributions; and a multivariate, periodic autoregressive model was used to reproduce the correlation structure. Each of the coefficients in the model is significantly different from zero at the 5-percent significance level. Coefficients relating spring inflow from one year to spring and fall inflows from the previous year had the largest effect on the lake-level frequency analysis.Inclusion of parameter uncertainty in the model for generating precipitation, evaporation, and inflow indicates that the upper lake-level exceedance levels from the water mass-balance model are particularly sensitive to parameter uncertainty. The sensitivity in the upper exceedance levels was caused almost entirely by uncertainty in the fitted probability distributions of the quarterly inflows. A method was developed for using long-term streamflow data for the Red River of the North at Grand Forks to reduce the variance in the estimated mean.Comparison of the annual lake-volume model and the water mass-balance model indicates the upper exceedance levels of the water mass-balance model increase much more rapidly than those of the annual lake-volume model. As an example, for simulation year 5, the 99-percent exceedance for the lake level is 1,417.6 feet above sea level for the annual lake-volume model and 1,423.2 feet above sea level for the water mass-balance model. The rapid increase is caused largely by the record precipitation and inflow in the summer and fall of 1993. Because the water mass-balance model produces lake-level traces that closely match the hydrology of Devils Lake, the water mass-balance model is superior to the annual lake-volume model for computing exceedance levels for the 50-year planning horizon.

Lake-level frequency analysis for Devils Lake, North Dakota

USGS Publications Warehouse

Wiche, Gregg J.; Vecchia, Aldo V.

1995-01-01

Two approaches were used to estimate future lake-level probabilities for Devils Lake. The first approach is based on an annual lake-volume model, and the second approach is based on a statistical water mass-balance model that generates seasonal lake volumes on the basis of seasonal precipitation, evaporation, and inflow.Autoregressive moving average models were used to model the annual mean lake volume and the difference between the annual maximum lake volume and the annual mean lake volume. Residuals from both models were determined to be uncorrelated with zero mean and constant variance. However, a nonlinear relation between the residuals of the two models was included in the final annual lake-volume model.Because of high autocorrelation in the annual lake levels of Devils Lake, the annual lakevolume model was verified using annual lake-level changes. The annual lake-volume model closely reproduced the statistics of the recorded lake-level changes for 1901-93 except for the skewness coefficient However, the model output is less skewed than the data indicate because of some unrealistically large lake-level declines.The statistical water mass-balance model requires as inputs seasonal precipitation, evaporation, and inflow data for Devils Lake. Analysis of annual precipitation, evaporation, and inflow data for 1950-93 revealed no significant trends or long-range dependence so the input time series were assumed to be stationary and short-range dependent.Normality transformations were used to approximately maintain the marginal probability distributions; and a multivariate, periodic autoregressive model was used to reproduce the correlation structure. Each of the coefficients in the model is significantly different from zero at the 5-percent significance level. Coefficients relating spring inflow from one year to spring and fall inflows from the previous year had the largest effect on the lake-level frequency analysis.Inclusion of parameter uncertainty in the model for generating precipitation, evaporation, and inflow indicates that the upper lake-level exceedance levels from the water mass-balance model are particularly sensitive to parameter uncertainty. The sensitivity in the upper exceedance levels was caused almost entirely by uncertainty in the fitted probability distributions of the quarterly inflows. A method was developed for using long-term streamflow data for the Red River of the North at Grand Forks to reduce the variance in the estimated mean. Comparison of the annual lake-volume model and the water mass-balance model indicates the upper exceedance levels of the water mass-balance model increase much more rapidly than those of the annual lake-volume model. As an example, for simulation year 5, the 99-percent exceedance for the lake level is 1,417.6 feet above sea level for the annual lake-volume model and 1,423.2 feet above sea level for the water mass-balance model. The rapid increase is caused largely by the record precipitation and inflow in the summer and fall of 1993. Because the water mass-balance model produces lake-level traces that closely match the hydrology of Devils Lake, the water mass-balance model is superior to the annual lake-volume model for computing exceedance levels for the 50-year planning horizon.

Moisture and drug solid-state monitoring during a continuous drying process using empirical and mass balance models.

PubMed

Fonteyne, Margot; Gildemyn, Delphine; Peeters, Elisabeth; Mortier, Séverine Thérèse F C; Vercruysse, Jurgen; Gernaey, Krist V; Vervaet, Chris; Remon, Jean Paul; Nopens, Ingmar; De Beer, Thomas

2014-08-01

Classically, the end point detection during fluid bed drying has been performed using indirect parameters, such as the product temperature or the humidity of the outlet drying air. This paper aims at comparing those classic methods to both in-line moisture and solid-state determination by means of Process Analytical Technology (PAT) tools (Raman and NIR spectroscopy) and a mass balance approach. The six-segmented fluid bed drying system being part of a fully continuous from-powder-to-tablet production line (ConsiGma™-25) was used for this study. A theophylline:lactose:PVP (30:67.5:2.5) blend was chosen as model formulation. For the development of the NIR-based moisture determination model, 15 calibration experiments in the fluid bed dryer were performed. Six test experiments were conducted afterwards, and the product was monitored in-line with NIR and Raman spectroscopy during drying. The results (drying endpoint and residual moisture) obtained via the NIR-based moisture determination model, the classical approach by means of indirect parameters and the mass balance model were then compared. Our conclusion is that the PAT-based method is most suited for use in a production set-up. Secondly, the different size fractions of the dried granules obtained during different experiments (fines, yield and oversized granules) were compared separately, revealing differences in both solid state of theophylline and moisture content between the different granule size fractions. Copyright © 2014 Elsevier B.V. All rights reserved.

Continuous succinic acid production from xylose by Actinobacillus succinogenes.

PubMed

Bradfield, Michael F A; Nicol, Willie

2016-02-01

Continuous, anaerobic fermentations of D-xylose were performed by Actinobacillus succinogenes 130Z in a custom, biofilm reactor at dilution rates of 0.05, 0.10 and 0.30 h(-1). Succinic acid yields on xylose (0.55-0.68 g g(-1)), titres (10.9-29.4 g L(-1)) and productivities (1.5-3.4 g L(-1) h(-1)) were lower than those of a previous study on glucose, but product ratios (succinic acid/acetic acid = 3.0-5.0 g g(-1)) and carbohydrate consumption rates were similar. Also, mass balance closures on xylose were up to 18.2 % lower than those on glucose. A modified HPLC method revealed pyruvic acid excretion at appreciable concentrations (1.2-1.9 g L(-1)) which improved the mass balance closure by up to 16.8 %. Furthermore, redox balances based on the accounted xylose consumed and the excreted metabolites, indicated an overproduction of reducing power. The oxidative pentose phosphate pathway was shown to be a plausible source of the additional reducing power.

Glacier mass balance and its potential impacts in the Altai Mountains over the period 1990-2011

NASA Astrophysics Data System (ADS)

Zhang, Yong; Enomoto, Hiroyuki; Ohata, Tetsuo; Kitabata, Hideyuki; Kadota, Tsutomu; Hirabayashi, Yukiko

2017-10-01

The Altai Mountains contain 1281 glaciers covering an area of 1191 km2. These glaciers have undergone significant changes in glacial length and area over the past decade. However, mass changes of these glaciers and their impacts remain poorly understood. Here we present surface mass balances of all glaciers in the region for the period 1990-2011, using a glacier mass-balance model forced by the outputs of a regional climate model. Our results indicate that the mean specific mass balance for the whole region is about -0.69 m w.e. yr-1 over the entire period, and about 81.3% of these glaciers experience negative net mass balance. We detect an accelerated wastage of these glaciers in recent years, and marked differences in mass change and its sensitivity to climate change for different regions and size classes. In particular, higher mass loss and temperature sensitivity are observed for glaciers smaller than 0.5 km2. In addition to temperature rise, a decrease in precipitation in the western part of the region and an increase in precipitation in the eastern part likely contribute to significant sub-region differences in mass loss. With significant glacier wastage, the contribution of all glaciers to regional water resources and sea-level change becomes larger than before, but may not be a potential threat to human populations through impacts on water availability.

A Membrane Gas Separation Experiment for the Undergraduate Laboratory.

ERIC Educational Resources Information Center

Davis, Richard A.; Sandall, Orville C.

1991-01-01

Described is a membrane experiment that provides students with experience in fundamental engineering skills such as mass balances, modeling, and using the computer as a research tool. Included are the experimental design, theory, method of solution, sample calculations, and conclusions. (KR)

RECENT APPLICATIONS OF SOURCE APPORTIONMENT METHODS AND RELATED NEEDS

EPA Science Inventory

Traditional receptor modeling studies have utilized factor analysis (like principal component analysis, PCA) and/or Chemical Mass Balance (CMB) to assess source influences. The limitations with these approaches is that PCA is qualitative and CMB requires the input of source pr...

Annual Greenland Accumulation Rates (2009-2012) from Airborne Snow Radar

NASA Technical Reports Server (NTRS)

Koenig, Lora S.; Ivanoff, Alvaro; Alexander, Patrick M.; MacGregor, Joseph A.; Fettweis, Xavier; Panzer, Ben; Paden, John D.; Forster, Richard R.; Das, Indrani; McConnell, Joseph R.;

A Smartphone Inertial Balance

ERIC Educational Resources Information Center

Barrera-Garrido, Azael

2017-01-01

In order to measure the mass of an object in the absence of gravity, one useful tool for many decades has been the inertial balance. One of the simplest forms of inertial balance is made by two mass holders or pans joined together with two stiff metal plates, which act as springs.

Coil motion effects in watt balances: a theoretical check

NASA Astrophysics Data System (ADS)

Li, Shisong; Schlamminger, Stephan; Haddad, Darine; Seifert, Frank; Chao, Leon; Pratt, Jon R.

2016-04-01

A watt balance is a precision apparatus for the measurement of the Planck constant that has been proposed as a primary method for realizing the unit of mass in a revised International System of Units. In contrast to an ampere balance, which was historically used to realize the unit of current in terms of the kilogram, the watt balance relates electrical and mechanical units through a virtual power measurement and has far greater precision. However, because the virtual power measurement requires the execution of a prescribed motion of a coil in a fixed magnetic field, systematic errors introduced by horizontal and rotational deviations of the coil from its prescribed path will compromise the accuracy. We model these potential errors using an analysis that accounts for the fringing field in the magnet, creating a framework for assessing the impact of this class of errors on the uncertainty of watt balance results.

Mass and surface energy balance of A.P. Olsen ice cap, NE Greenland, from observations and modeling (1995-2011)

NASA Astrophysics Data System (ADS)

Hillerup Larsen, S.; Citterio, M.; Hock, R. M.; Ahlstrom, A. P.

2012-12-01

The A.P. Olsen Ice Cap (74.6 N, 21.5 W) in NE Greenland covers an area of 295 km2, is composed by two domes, of which the western is the largest, and spans an elevation range between 200 and 1450 m a.s.l. In this study we calculate the 2008-2011 annual glacier mass balance based on in situ observations, we model the surface energy balance over the same period, and we reconstruct annual glacier mass balance since 1995. We use GlacioBasis Monitoring Programme observations from a network of 15 ablation stakes and three automatic weather stations (AWS) at 600 m (ca. 100 m higher than the terminus) and at 840 m on the main glacier outlet of the western dome, and at 1430 m in the accumulation area. Accumulation is measured every year in springtime by snow radar surveys calibrated with manual probing and density profiles from snow pits. GlacioBasis data start in 2008, but a longer time series starting in 1995 is available from a weather station at 44 m a.s.l. close to Zackenberg Research Station, ca. 30 km further west. Shorter data series from three more AWS on land at 145 m, 410 m and 1283 m a.s.l. are used to estimate monthly average temperature lapse rates outside of the glacier boundary layer, and to detect the occurrence of temperature inversions. The surface energy mass balance is dominated by the radiative fluxes. We discuss the effect of shadows from the valley sides over parts of the tongue, especially early and late in the melt season when the sun is lower over the horizon, and analyze the modeled mass balance sensitivity to a 1 °C temperature increase. A temperature index model driven by the 1995-2008 time series and calibrated using post-2008 glacier mass balance measurements shows large interannual variability, with 5 of the most negative mass balance years of the entire 1995-2011period occurring between 2003 and 2008. In particular during 2008 the glacier experienced almost no net accumulation over the entire elevation range. This matches 2008 mass balance observations at Freya Glacier on Clavering Island, ca. 40 km SW of A.P. Olsen (WGMS Gl. Mass Bal. Bull. n. 11, 2011).

A 350-year reconstruction of the response of south Cascade Glacier to interannual and interdecadal climatic variability

Treesearch

Kailey W. Marcinkowski; David L. Peterson

2015-01-01

Mountain hemlock growth chronologies were used to reconstruct the mass balance of South Cascade Glacier, an alpine glacier in the North Cascade Range of Washington State. The net balance reconstruction spans 350 years, from 1659 to 2009. Summer and winter balances were reconstructed for 1346–2009 and 1615–2009, respectively. Relationships between mass balance and...

DEVELOPMENT OF AN EMISSION FACTOR FOR AMMONIA EMISSIONS FROM U.S. SWINE FARMS BASED ON FIELD TESTS AND APPLICATION OF A MASS BALANCE METHOD

EPA Science Inventory

This paper summarizes and discusses recent available U.S. and European information on
ammonia (NH3) emissions from swine farms and assesses the applicability for general use
in the United States. The emission rates for the swine barns calculated by various methods show
g...

50 years of mass balance observations at Vernagtferner, Eastern Alps

NASA Astrophysics Data System (ADS)

Braun, Ludwig; Mayer, Christoph

2016-04-01

The determination and monitoring of the seasonal and annual glacier mass balances of Vernagtferner, Austria, started in 1964 by the Commission of Glaciology, Bavarian Academy of Sciences. Detailed and continuous climate- and runoff measurements complement this mass balance series since 1974. Vernagtferner attracted the attention of scientists since the beginning of the 17th century due to its rapid advances and the resulting glacier lake outburst floods in the Ötztal valley. This is one reason for the first photogrammetric survey in 1889, which was followed by frequent topographic surveys, adding up to more than ten digital elevation models of the glacier until today. By including the known maximum glacier extent at the end of the Little Ice Age in 1845, the geodetic glacier volume balances cover a time span of almost 170 years. The 50 years of glacier mass balance and 40 years of water balance in the drainage basin are therefore embedded in a considerably longer period of glacier evolution, allowing an interpretation within an extended frame of climatology and ice dynamics. The direct mass balance observations cover not only the period of alpine-wide strong glacier mass loss since the beginning of the 1990s. The data also contain the last period of glacier advances between 1970 and 1990. The combination of the observed surface mass exchange and the determined periodic volumetric changes allows a detailed analysis of the dynamic reaction of the glacier over the period of half a century. The accompanying meteorological observations are the basis for relating these reactions to the climatic changes during this period. Vernagtferner is therefore one of the few glaciers in the world, where a very detailed glacier-climate reaction was observed for many decades and can be realistically reconstructed back to the end of the Little Ice Age.

Energy balance and runoff modelling of glaciers in the Kongsfjord basin in northwestern Svalbard

NASA Astrophysics Data System (ADS)

Kohler, J.; Pramanik, A.; van Pelt, W.

2016-12-01

Glaciers and ice caps cover 36,000 Km2 or 60% of the land area of the Svalbard archipelago. Roughly 60% of the glaciated area drains to the ocean through tidewater glacier fronts. Runoff from tidewater glaciers is posited to have a significant impact on fjord circulation and thereby on fjord ecosystems. Ocean circulation modelling underway in the Kongsfjord system requires specification of the freshwater amounts contributed by both tidewater and land-terminating glaciers in its basin. The total basin area of Kongsfjord is 1850 km2. We use a coupled surface energy-balance and firn model (Van Pelt et al. 2015) to calculate mass balance and runoff from the Kongsfjord glaciers for the period 1969-2015. Meteorological data from the nearby station at Ny-Ålesund is used for climate forcing in the model domain, with mass balance data at four glaciers in the Kongsfjord watershed used to calibrate model parameters. Precipitation and temperature lapse rates are adjusted on the study glaciers through repeated model runs at mass balance stake locations to match observed and modelled surface mass balance. Long-term discharge measurement at two sites in this region are used to validate the modelled runoff. Spatial and temporal evolution of melt, refreezing and runoff are analyzed, along with the vertical evolution of subsurface conditions. Reference: Van Pelt, W.J.J. & J. Kohler. 2015. Modelling the long-term mass balance and firn evolution of glaciers around Kongsfjorden, Svalbard. J. Glaciol, 61(228), 731-744. Glaciers and ice caps cover 36,000 Km2 or 60% of the land area of the Svalbard archipelago. Roughly 60% of the glaciated area drains to the ocean through tidewater glacier fronts. Runoff from tidewater glaciers is posited to have a significant impact on fjord circulation and thereby on fjord ecosystems. Ocean circulation modelling underway in the Kongsfjord system requires specification of the freshwater amounts contributed by both tidewater and land-terminating glaciers in its basin. The total basin area of Kongsfjord is 1850 km2. We use a coupled surface energy-balance and firn model (Van Pelt et al. 2015) to calculate mass balance and runoff from the Kongsfjord glaciers for the period 1969-2015. Meteorological data from the nearby station at Ny-Ålesund is used for climate forcing in the model domain, with mass balance data at four glaciers in the Kongsfjord watershed used to calibrate model parameters. Precipitation and temperature lapse rates are adjusted on the study glaciers through repeated model runs at mass balance stake locations to match observed and modelled surface mass balance. Long-term discharge measurement at two sites in this region are used to validate the modelled runoff. Spatial and temporal evolution of melt, refreezing and runoff are analyzed, along with the vertical evolution of subsurface conditions. Reference: Van Pelt, W.J.J. & J. Kohler. 2015. Modelling the long-term mass balance and firn evolution of glaciers around Kongsfjorden, Svalbard. J. Glaciol, 61(228), 731-744.

Greenland ice sheet mass balance: a review.

PubMed

Khan, Shfaqat A; Aschwanden, Andy; Bjørk, Anders A; Wahr, John; Kjeldsen, Kristian K; Kjær, Kurt H

2015-04-01

Over the past quarter of a century the Arctic has warmed more than any other region on Earth, causing a profound impact on the Greenland ice sheet (GrIS) and its contribution to the rise in global sea level. The loss of ice can be partitioned into processes related to surface mass balance and to ice discharge, which are forced by internal or external (atmospheric/oceanic/basal) fluctuations. Regardless of the measurement method, observations over the last two decades show an increase in ice loss rate, associated with speeding up of glaciers and enhanced melting. However, both ice discharge and melt-induced mass losses exhibit rapid short-term fluctuations that, when extrapolated into the future, could yield erroneous long-term trends. In this paper we review the GrIS mass loss over more than a century by combining satellite altimetry, airborne altimetry, interferometry, aerial photographs and gravimetry data sets together with modelling studies. We revisit the mass loss of different sectors and show that they manifest quite different sensitivities to atmospheric and oceanic forcing. In addition, we discuss recent progress in constructing coupled ice-ocean-atmosphere models required to project realistic future sea-level changes.

Modeled and measured glacier change and related glaciological, hydrological, and meteorological conditions at South Cascade Glacier, Washington, balance and water years 2006 and 2007

USGS Publications Warehouse

Bidlake, William R.; Josberger, Edward G.; Savoca, Mark E.

2010-01-01

Winter snow accumulation and summer snow and ice ablation were measured at South Cascade Glacier, Washington, to estimate glacier mass balance quantities for balance years 2006 and 2007. Mass balances were computed with assistance from a new model that was based on the works of other glacier researchers. The model, which was developed for mass balance practitioners, coupled selected meteorological and glaciological data to systematically estimate daily mass balance at selected glacier sites. The North Cascade Range in the vicinity of South Cascade Glacier accumulated approximately average to above average winter snow packs during 2006 and 2007. Correspondingly, the balance years 2006 and 2007 maximum winter snow mass balances of South Cascade Glacier, 2.61 and 3.41 meters water equivalent, respectively, were approximately equal to or more positive (larger) than the average of such balances since 1959. The 2006 glacier summer balance, -4.20 meters water equivalent, was among the four most negative since 1959. The 2007 glacier summer balance, -3.63 meters water equivalent, was among the 14 most negative since 1959. The glacier continued to lose mass during 2006 and 2007, as it commonly has since 1953, but the loss was much smaller during 2007 than during 2006. The 2006 glacier net balance, -1.59 meters water equivalent, was 1.02 meters water equivalent more negative (smaller) than the average during 1953-2005. The 2007 glacier net balance, -0.22 meters water equivalent, was 0.37 meters water equivalent less negative (larger) than the average during 1953-2006. The 2006 accumulation area ratio was less than 0.10, owing to isolated patches of accumulated snow that endured the 2006 summer season. The 2006 equilibrium line altitude was higher than the glacier. The 2007 accumulation area ratio and equilibrium line altitude were 0.60 and 1,880 meters, respectively. Accompanying the glacier mass losses were retreat of the terminus and reduction of total glacier area. The terminus retreated at a rate of about 13 meters per year during balance year 2006 and at a rate of about 8 meters per year during balance year 2007. Glacier area near the end of balance years 2006 and 2007 was 1.74 and 1.73 square kilometers, respectively. Runoff from the basin containing the glacier and from an adjacent nonglacierized basin was gaged during all or parts of water years 2006 and 2007. Air temperature, wind speed, precipitation, and incoming solar radiation were measured at selected locations on and near the glacier. Air-temperature over the glacier at a height of 2 meters generally was less than at the same altitude in the air mass away from the glacier. Cooling of the air by the glacier increased systematically with increasing ambient air temperature. Empirically based equations were developed to estimate 2-meter-height air temperature over the glacier at five sites from site altitude and temperature at a non-glacier reference site.

Mass-balance approach for assessing nitrate flux intidal wetlands -- lessons learned

EPA Science Inventory

Field experiments were carried out in 2010 and 2011 to assess the nitrate balance in a small tidal slough located in the Yaquina Estuary, Oregon. In 2010 we used a whole-slough, mass-balance approach, while a smaller scale, flume-like experiment in a tidal channel with a dense ...

On the impact of using downscaled reanalysis data instead of direct measurements for modeling the mass balance of a tropical glacier (Cordillera Blanca, Peru)

NASA Astrophysics Data System (ADS)

Galos, Stephan; Hofer, Marlis; Marzeion, Ben; Mölg, Thomas; Großhauser, Martin

2013-04-01

Due to their setting, tropical glaciers are sensitive indicators of mid-tropospheric meteorological variability and climate change. Furthermore these glaciers are of particular interest because they respond faster to climatic changes than glaciers located in mid- or high-latitudes. As long-term direct meteorological measurements in such remote environments are scarce, reanalysis data (e.g. ERA-Interim) provide a highly valuable source of information. Reanalysis datasets (i) enable a temporal extension of data records gained by direct measurements and (ii) provide information from regions where direct measurements are not available. In order to properly derive the physical exchange processes between glaciers and atmosphere from reanalysis data, downscaling procedures are required. In the present study we investigate if downscaled atmospheric variables (air temperature and relative humidity) from a reanalysis dataset can be used as input for a physically based, high resolution energy and mass balance model. We apply a well validated empirical-statistical downscaling model, fed with ERA-Interim data, to an automated weather station (AWS) on the surface of Glaciar Artesonraju (8.96° S | 77.63° W). The downscaled data is then used to replace measured air temperature and relative humidity in the input for the energy and mass balance model, which was calibrated using ablation data from stakes and a sonic ranger. In order to test the sensitivity of the modeled mass balance to the downscaled data, the results are compared to a reference model run driven solely with AWS data as model input. We finally discuss the results and present future perspectives for further developing this method.

Linking morphodynamic response with sediment mass balance on the Colorado River in Marble Canyon: issues of scale, geomorphic setting, and sampling design

USGS Publications Warehouse

Grams, Paul E.; Topping, David J.; Schmidt, John C.; Hazel, Joseph E.; Kaplinski, Matt

2013-01-01

Measurements of morphologic change are often used to infer sediment mass balance. Such measurements may, however, result in gross errors when morphologic changes over short reaches are extrapolated to predict changes in sediment mass balance for long river segments. This issue is investigated by examination of morphologic change and sediment influx and efflux for a 100 km segment of the Colorado River in Grand Canyon, Arizona. For each of four monitoring intervals within a 7 year study period, the direction of sand-storage response within short morphologic monitoring reaches was consistent with the flux-based sand mass balance. Both budgeting methods indicate that sand storage was stable or increased during the 7 year period. Extrapolation of the morphologic measurements outside the monitoring reaches does not, however, provide a reasonable estimate of the magnitude of sand-storage change for the 100 km study area. Extrapolation results in large errors, because there is large local variation in site behavior driven by interactions between the flow and local bed topography. During the same flow regime and reach-average sediment supply, some locations accumulate sand while others evacuate sand. The interaction of local hydraulics with local channel geometry exerts more control on local morphodynamic response than sand supply over an encompassing river segment. Changes in the upstream supply of sand modify bed responses but typically do not completely offset the effect of local hydraulics. Thus, accurate sediment budgets for long river segments inferred from reach-scale morphologic measurements must incorporate the effect of local hydraulics in a sampling design or avoid extrapolation altogether.

Balance rehabilitation: promoting the role of virtual reality in patients with diabetic peripheral neuropathy.

PubMed

Grewal, Gurtej S; Sayeed, Rashad; Schwenk, Michael; Bharara, Manish; Menzies, Robert; Talal, Talal K; Armstrong, David G; Najafi, Bijan

2013-01-01

Individuals with diabetic peripheral neuropathy frequently experience concomitant impaired proprioception and postural instability. Conventional exercise training has been demonstrated to be effective in improving balance but does not incorporate visual feedback targeting joint perception, which is an integral mechanism that helps compensate for impaired proprioception in diabetic peripheral neuropathy. This prospective cohort study recruited 29 participants (mean ± SD: age, 57 ± 10 years; body mass index [calculated as weight in kilograms divided by height in meters squared], 26.9 ± 3.1). Participants satisfying the inclusion criteria performed predefined ankle exercises through reaching tasks, with visual feedback from the ankle joint projected on a screen. Ankle motion in the mediolateral and anteroposterior directions was captured using wearable sensors attached to the participant's shank. Improvements in postural stability were quantified by measuring center of mass sway area and the reciprocal compensatory index before and after training using validated body-worn sensor technology. Findings revealed a significant reduction in center of mass sway after training (mean, 22%; P = .02). A higher postural stability deficit (high body sway) at baseline was associated with higher training gains in postural balance (reduction in center of mass sway) (r = -0.52, P < .05). In addition, significant improvement was observed in postural coordination between the ankle and hip joints (mean, 10.4%; P = .04). The present research implemented a novel balance rehabilitation strategy based on virtual reality technology. The method included wearable sensors and an interactive user interface for real-time visual feedback based on ankle joint motion, similar to a video gaming environment, for compensating impaired joint proprioception. These findings support that visual feedback generated from the ankle joint coupled with motor learning may be effective in improving postural stability in patients with diabetic peripheral neuropathy.

Biogenic carbon in combustible waste: waste composition, variability and measurement uncertainty.

PubMed

Larsen, Anna W; Fuglsang, Karsten; Pedersen, Niels H; Fellner, Johann; Rechberger, Helmut; Astrup, Thomas

2013-10-01

Obtaining accurate data for the contents of biogenic and fossil carbon in thermally-treated waste is essential for determination of the environmental profile of waste technologies. Relations between the variability of waste chemistry and the biogenic and fossil carbon emissions are not well described in the literature. This study addressed the variability of biogenic and fossil carbon in combustible waste received at a municipal solid waste incinerator. Two approaches were compared: (1) radiocarbon dating ((14)C analysis) of carbon dioxide sampled from the flue gas, and (2) mass and energy balance calculations using the balance method. The ability of the two approaches to accurately describe short-term day-to-day variations in carbon emissions, and to which extent these short-term variations could be explained by controlled changes in waste input composition, was evaluated. Finally, the measurement uncertainties related to the two approaches were determined. Two flue gas sampling campaigns at a full-scale waste incinerator were included: one during normal operation and one with controlled waste input. Estimation of carbon contents in the main waste types received was included. Both the (14)C method and the balance method represented promising methods able to provide good quality data for the ratio between biogenic and fossil carbon in waste. The relative uncertainty in the individual experiments was 7-10% (95% confidence interval) for the (14)C method and slightly lower for the balance method.

Multi-approach assessment of the spatial distribution of the specific yield: application to the Crau plain aquifer, France

NASA Astrophysics Data System (ADS)

Seraphin, Pierre; Gonçalvès, Julio; Vallet-Coulomb, Christine; Champollion, Cédric

2018-06-01

Spatially distributed values of the specific yield, a fundamental parameter for transient groundwater mass balance calculations, were obtained by means of three independent methods for the Crau plain, France. In contrast to its traditional use to assess recharge based on a given specific yield, the water-table fluctuation (WTF) method, applied using major recharging events, gave a first set of reference values. Then, large infiltration processes recorded by monitored boreholes and caused by major precipitation events were interpreted in terms of specific yield by means of a one-dimensional vertical numerical model solving Richards' equations within the unsaturated zone. Finally, two gravity field campaigns, at low and high piezometric levels, were carried out to assess the groundwater mass variation and thus alternative specific yield values. The range obtained by the WTF method for this aquifer made of alluvial detrital material was 2.9- 26%, in line with the scarce data available so far. The average spatial value of specific yield by the WTF method (9.1%) is consistent with the aquifer scale value from the hydro-gravimetric approach. In this investigation, an estimate of the hitherto unknown spatial distribution of the specific yield over the Crau plain was obtained using the most reliable method (the WTF method). A groundwater mass balance calculation over the domain using this distribution yielded similar results to an independent quantification based on a stable isotope-mixing model. This agreement reinforces the relevance of such estimates, which can be used to build a more accurate transient hydrogeological model.

Multi-approach assessment of the spatial distribution of the specific yield: application to the Crau plain aquifer, France

NASA Astrophysics Data System (ADS)

Seraphin, Pierre; Gonçalvès, Julio; Vallet-Coulomb, Christine; Champollion, Cédric

2018-03-01

Spatially distributed values of the specific yield, a fundamental parameter for transient groundwater mass balance calculations, were obtained by means of three independent methods for the Crau plain, France. In contrast to its traditional use to assess recharge based on a given specific yield, the water-table fluctuation (WTF) method, applied using major recharging events, gave a first set of reference values. Then, large infiltration processes recorded by monitored boreholes and caused by major precipitation events were interpreted in terms of specific yield by means of a one-dimensional vertical numerical model solving Richards' equations within the unsaturated zone. Finally, two gravity field campaigns, at low and high piezometric levels, were carried out to assess the groundwater mass variation and thus alternative specific yield values. The range obtained by the WTF method for this aquifer made of alluvial detrital material was 2.9- 26%, in line with the scarce data available so far. The average spatial value of specific yield by the WTF method (9.1%) is consistent with the aquifer scale value from the hydro-gravimetric approach. In this investigation, an estimate of the hitherto unknown spatial distribution of the specific yield over the Crau plain was obtained using the most reliable method (the WTF method). A groundwater mass balance calculation over the domain using this distribution yielded similar results to an independent quantification based on a stable isotope-mixing model. This agreement reinforces the relevance of such estimates, which can be used to build a more accurate transient hydrogeological model.

Improving the XAJ Model on the Basis of Mass-Energy Balance

NASA Astrophysics Data System (ADS)

Fang, Yuanhao; Corbari, Chiara; Zhang, Xingnan; Mancini, Marco

2014-11-01

Introduction: The Xin'anjiang(XAJ) model is a conceptual model developed by the group led by Prof. Ren-Jun Zhao, which takes the pan evaporation as one of its input and then computes the effective evapotranspiration (ET) of the catchment by mass balance. Such scheme can ensure a good performance of discharge simulation but has obvious defects, one of which is that the effective ET is spatially-constant over the computation unit, neglecting the spatial variation of variables that influence the effective ET and therefore the simulation of ET and SM by the XAJ model, comparing with discharge, is less reliable. In this study, The XAJ model was improved to employ both energy and mass balance to compute the ET following the energy-mass balance scheme of FEST-EWB. model.

Improving the XAJ Model on the Basis of Mass-Energy Balance

NASA Astrophysics Data System (ADS)

Fang, Yuanghao; Corbari, Chiara; Zhang, Xingnan; Mancini, Marco

2014-11-01

The Xin’anjiang(XAJ) model is a conceptual model developed by the group led by Prof. Ren-Jun Zhao, which takes the pan evaporation as one of its input and then computes the effective evapotranspiration (ET) of the catchment by mass balance. Such scheme can ensure a good performance of discharge simulation but has obvious defects, one of which is that the effective ET is spatially-constant over the computation unit, neglecting the spatial variation of variables that influence the effective ET and therefore the simulation of ET and SM by the XAJ model, comparing with discharge, is less reliable. In this study, The XAJ model was improved to employ both energy and mass balance to compute the ET following the energy-mass balance scheme of FEST-EWB. model.

Mass fraction assignment of folic acid in a high purity material

NASA Astrophysics Data System (ADS)

Westwood, Steven; Josephs, Ralf; Choteau, Tiphaine; Daireaux, Adeline; Stoppacher, Norbert; Wielgosz, Robert; Davies, Stephen; de Rego, Eliane; Wollinger, Wagner; Garrido, Bruno; Fernandes, Jane; Lima, Jonathan; Oliveira, Rodrigo; de Sena, Rodrigo; Windust, Anthony; Huang, Ting; Dai, Xinhua; Quan, Can; He, Haihong; Zhang, Wei; Wei, Chao; Li, Na; Gao, Dexin; Liu, Zhao; Lo, Man-fung; Wong, Wai-fun; Pfeifer, Dietmar; Koch, Matthias; Dorgerloh, Ute; Rothe, Robert; Philip, Rosemary; Hirari, Nobuyasu; Fazlin Rezali, Mohd; Salazar Arzate, Claudia Marcela; Pedraza Evelina Berenice, Mercado; Serrano Caballero, Victor; Arce Osuna, Mariana; Krylov, A.; Kharitonov, S.; Lopushanskaya, E.; Liu, Qinde; Tang Lin, Teo; Fernandes-Whaley, Maria; Quinn, Laura; Nhlapo, Nontete; Prevoo-Franzsen, Desiree; Archer, Marcelle; Kim, Byungjoo; Baek, Song-Yee; Lee, Sunyoung; Lee, Joonhee; Marbumrung, Sornkrit; Kankaew, Ponhatai; Chaorenpornpukdee, Kanokrat; Chaipet, Thitiphan; Shearman, Kittiya; Ceyhan Goren, Ahmet; Gunduz, Simay; Yilmaz, Hasibe; Un, Ilker; Bilsel, Gokhan; Clarkson, Cailean; Bedner, Mary; Camara, Johanna E.; Lang, Brian E.; Lippa, Katrice A.; Nelson, Michael A.; Toman, Blaza; Yu, Lee L.

2018-01-01

The comparison required the assignment of the mass fraction of folic acid present as the main component in the comparison sample. Performance in the comparison is representative of a laboratory's measurement capability for the purity assignment of organic compounds of medium structural complexity [molecular weight range 300–500] and high polarity (pKOW < ‑2). Methods used by the eighteen participating NMIs or DIs were based on a mass balance (summation of impurities) or qNMR approach, or the combination of data obtained using both methods. The qNMR results tended to give slightly lower values for the content of folic acid, albeit with larger associated uncertainties, compared with the results obtained by mass balance procedures. Possible reasons for this divergence are discussed in the report, without reaching a definitive conclusion as to their origin. The comparison demonstrates that for a structurally complex polar organic compound containing a high water content and presenting a number of additional analytical challenges, the assignment of the mass fraction content property value of the main component can reasonably be achieved with an associated relative standard uncertainty in the assigned value of 0.5% Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Postural alignment in children with Duchenne muscular dystrophy and its relationship with balance

PubMed Central

Baptista, Cyntia R. J. A.; Costa, Andreia A.; Pizzato, Tatiana M.; Souza, Francine B.; Mattiello-Sverzut, Ana C.

2014-01-01

Background In Duchenne muscular dystrophy, functional deficits seem to arise from body misalignment, deconditioning, and obesity secondary to weakness and immobility. The question remains about the effects of postural deviations on the functional balance of these children. Objectives To identify and quantify postural deviations in children with DMD in comparison to non-affected children (eutrophic and overweight/obese), exploring relationships between posture and function. Method This case-control study evaluated 29 participants aged 6 to 11 years: 10 DMD (DG), 10 eutrophic (EG), and 9 overweight/obese (OG). Digital photogrammetry and SAPo program were used to measure postural alignment and the Pediatric Balance Scale (PBS) was used to measure balance. The Kruskall-Wallis and Dunn post-hoc tests were used for inter-group comparison of posture and balance. Spearman's coefficient tested the correlation between postural and balance variables. Results The horizontal pelvic alignment data indicated that the anteversion of the DG was similar to that of the OG and twice that of the EG (p<0.05). Compared to the EG, the DG and OG showed an increased forward position of the center of mass (p<0.05). There was a moderate and weak correlation between the PBS score and horizontal pelvic alignment (0.58 and 0.47-left/right). The PBS showed a weak correlation with asymmetries in the sagittal plane (-0.39). The PBS scores for the OG and EG suggest that obesity did not have a deleterious effect on balance. Conclusions The balance deficit in children with DMD was accompanied by an increased forward position of the center of mass and significant pelvic anteversion that constitutes a compensatory strategy to guarantee similar performance to the children not affected by the disease. PMID:24838810

The importance of accurate glacier albedo for estimates of surface mass balance on Vatnajökull: Evaluating the surface energy budget in a Regional Climate Model with automatic weather station observations

NASA Astrophysics Data System (ADS)

Steffensen Schmidt, Louise; Aðalgeirsdóttir, Guðfinna; Guðmundsson, Sverrir; Langen, Peter L.; Pálsson, Finnur; Mottram, Ruth; Gascoin, Simon; Björnsson, Helgi

2017-04-01

The evolution of the surface mass balance of Vatnajökull ice cap, Iceland, from 1981 to the present day is estimated by using the Regional Climate Model HIRHAM5 to simulate the surface climate. A new albedo parametrization is used for the simulation, which describes the albedo with an exponential decay with time. In addition, it utilizes a new background map of the ice albedo created from MODIS data. The simulation is validated against observed daily values of weather parameters from five Automatic Weather Stations (AWSs) from 2001-2014, as well as mass balance measurements from 1995-2014. The modelled albedo is overestimated at the AWS sites in the ablation zone, which we attribute to an overestimation of the thickness of the snow layer and the model not accounting for dust and ash deposition during dust storms and volcanic eruptions. A comparison with the specific summer, winter, and annual mass balance for all Vatnajökull from 1995-2014 shows a good overall fit during the summer, with the model underestimating the balance by only 0.04 m w. eq. on average. The winter balance, on the other hand, is overestimated by 0.5 m w. eq. on average, mostly due to an overestimation of the precipitation at the highest areas of the ice cap. A simple correction of the accumulation at these points reduced the error to 0.15 m w. eq. The model captures the evolution of the specific mass balance well, for example it captures an observed shift in the balance in the mid-1990s, which gives us confidence in the results for the entire model run. Our results show the importance of bare ice albedo for modelled mass balance and that processes not currently accounted for in RCMs, such as dust storms, are an important source of uncertainty in estimates of the snow melt rate.

A 30-year record of surface mass balance (1966-95) and motion and surface altitude (1975-95) at Wolverine Glacier, Alaska

USGS Publications Warehouse

Mayo, Lawrence R.; Trabant, Dennis C.; March, Rod S.

2004-01-01

Scientific measurements at Wolverine Glacier, on the Kenai Peninsula in south-central Alaska, began in April 1966. At three long-term sites in the research basin, the measurements included snow depth, snow density, heights of the glacier surface and stratigraphic summer surfaces on stakes, and identification of the surface materials. Calculations of the mass balance of the surface strata-snow, new firn, superimposed ice, and old firn and ice mass at each site were based on these measurements. Calculations of fixed-date annual mass balances for each hydrologic year (October 1 to September 30), as well as net balances and the dates of minimum net balance measured between time-transgressive summer surfaces on the glacier, were made on the basis of the strata balances augmented by air temperature and precipitation recorded in the basin. From 1966 through 1995, the average annual balance at site A (590 meters altitude) was -4.06 meters water equivalent; at site B (1,070 meters altitude), was -0.90 meters water equivalent; and at site C (1,290 meters altitude), was +1.45 meters water equivalent. Geodetic determination of displacements of the mass balance stake, and glacier surface altitudes was added to the data set in 1975 to detect the glacier motion responses to variable climate and mass balance conditions. The average surface speed from 1975 to 1996 was 50.0 meters per year at site A, 83.7 meters per year at site B, and 37.2 meters per year at site C. The average surface altitudes were 594 meters at site A, 1,069 meters at site B, and 1,293 meters at site C; the glacier surface altitudes rose and fell over a range of 19.4 meters at site A, 14.1 meters at site B, and 13.2 meters at site C.

A comparative study of volatile contents of primitive arc bubble-bearing melt inclusions determined by Raman-spectroscopy and mass-balance versus experimental homogenization methods

NASA Astrophysics Data System (ADS)

Moore, L.; Mironov, N.; Portnyagin, M.; Gazel, E.; Bodnar, R. J.

2016-12-01

Primitive olivine-hosted melt inclusions (MI) are a useful means to estimate the pre-eruptive volatile contents of a volcanic melts but post-entrapment processes complicate this approach. In particular, crystallization of the host phase along the wall of the MI and diffusion of H+ through the host cause CO2 and potentially S or other volatiles to exsolve from the melt to a separate fluid bubble. Recently, experimental rehydration and Raman spectroscopy have become potential methods for restoring the volatile contents of MI by rehomogenization or through mass balance calculations respectively. In order to compare these two approaches, we have studied MI from a single suite of samples from Klyuchevsky volcano (Kamchatka Arc) that have been treated with both experimental rehydration and analyzed using Raman spectroscopy. The maximum MI CO2 contents are in agreement ( 4000 ppm) regardless of the method used to account for CO2 in the bubble, but there is significantly more scatter to lower values using the Raman method which can be attributed to uncertainty related to mass balance calculations and carbonate daughter minerals that have formed at the glass-bubble interface. The presence of S- and C-bearing daughter minerals on the surface of the bubble in unheated melt inclusions indicates that to obtain more confident results with Raman spectroscopy, naturally quenched MIs should be also shortly reheated to dissolve most or all the crystals at the glass-bubble interface. Concerning H2O, MI from the unheated tephra samples contain less H2O than rehydrated MI in lavas. Determining the original H2O content of rehydrated MI is difficult because the H2O concentration in the glass is controlled by the conditions during the rehydration experiment. Thus reconciling the initial H2O content in primitive arc MIs (and degree of H2O loss) still remains a challenging task.

Effects of Easy-to-Use Protein-Rich Energy Bar on Energy Balance, Physical Activity and Performance during 8 Days of Sustained Physical Exertion

PubMed Central

Tanskanen, Minna M.; Westerterp, Klaas R.; Uusitalo, Arja L.; Atalay, Mustafa; Häkkinen, Keijo; Kinnunen, Hannu O.; Kyröläinen, Heikki

2012-01-01

Background Previous military studies have shown an energy deficit during a strenuous field training course (TC). This study aimed to determine the effects of energy bar supplementation on energy balance, physical activity (PA), physical performance and well-being and to evaluate ad libitum fluid intake during wintertime 8-day strenuous TC. Methods Twenty-six men (age 20±1 yr.) were randomly divided into two groups: The control group (n = 12) had traditional field rations and the experimental (Ebar) group (n = 14) field rations plus energy bars of 4.1 MJ•day−1. Energy (EI) and water intake was recorded. Fat-free mass and water loss were measured with deuterium dilution and elimination, respectively. The energy expenditure was calculated using the intake/balance method and energy availability as (EI/estimated basal metabolic rate). PA was monitored using an accelerometer. Physical performance was measured and questionnaires of upper respiratory tract infections (URTI), hunger and mood state were recorded before, during and after TC. Results Ebar had a higher EI and energy availability than the controls. However, decreases in body mass and fat mass were similar in both groups representing an energy deficit. No differences were observed between the groups in PA, water balance, URTI symptoms and changes in physical performance and fat-free mass. Ebar felt less hunger after TC than the controls and they had improved positive mood state during the latter part of TC while controls did not. Water deficit associated to higher PA. Furthermore, URTI symptoms and negative mood state associated negatively with energy availability and PA. Conclusion An easy-to-use protein-rich energy bars did not prevent energy deficit nor influence PA during an 8-day TC. The high content of protein in the bars might have induced satiation decreasing energy intake from field rations. PA and energy intake seems to be primarily affected by other factors than energy supplementation such as mood state. PMID:23094083

Watt and joule balances

NASA Astrophysics Data System (ADS)

Robinson, Ian A.

2014-04-01

The time is fast approaching when the SI unit of mass will cease to be based on a single material artefact and will instead be based upon the defined value of a fundamental constant—the Planck constant—h . This change requires that techniques exist both to determine the appropriate value to be assigned to the constant, and to measure mass in terms of the redefined unit. It is important to ensure that these techniques are accurate and reliable to allow full advantage to be taken of the stability and universality provided by the new definition and to guarantee the continuity of the world's mass measurements, which can affect the measurement of many other quantities such as energy and force. Up to now, efforts to provide the basis for such a redefinition of the kilogram were mainly concerned with resolving the discrepancies between individual implementations of the two principal techniques: the x-ray crystal density (XRCD) method [1] and the watt and joule balance methods which are the subject of this special issue. The first three papers report results from the NRC and NIST watt balance groups and the NIM joule balance group. The result from the NRC (formerly the NPL Mk II) watt balance is the first to be reported with a relative standard uncertainty below 2 × 10-8 and the NIST result has a relative standard uncertainty below 5 × 10-8. Both results are shown in figure 1 along with some previous results; the result from the NIM group is not shown on the plot but has a relative uncertainty of 8.9 × 10-6 and is consistent with all the results shown. The Consultative Committee for Mass and Related Quantities (CCM) in its meeting in 2013 produced a resolution [2] which set out the requirements for the number, type and quality of results intended to support the redefinition of the kilogram and required that there should be agreement between them. These results from NRC, NIST and the IAC may be considered to meet these requirements and are likely to be widely debated prior to a decision on redefinition. The CCM had already recognized that agreement was close and has set in place a process whereby redefinition can take place by 2018. The final decision will be in the hands of the Conférence Générale des Poids et Mesures (CGPM) but the results reported here should aid a positive decision. Figure 1. Figure 1. Results from recent measurements of the Planck constant. The reference for the results h 90 is derived from the conventional values of the Josephson constant K J-90 and the von Klitzing constant R K-90. The factor of ten improvement in uncertainty of the NRC watt balance result, over that achieved by the same apparatus at NPL a few years earlier, can be understood as a factor of five improvement arising from the elimination of an effect discovered at NPL that could not be eliminated before shipment to Canada and a factor of two arising from the considerable improvements made by NRC. Once the kilogram has been redefined, the watt and joule balances will complete their transitions from instruments that are primarily of interest to the electrical community for determining the SI electrical units from the mechanical units, to the principal methods by which an individual National Measurement Institute (NMI) can make an independent determination of the SI unit of mass and thereby contribute to the maintenance of national and international mass scales. This special issue gives an introduction to the diversity of techniques which are required for the operation of watt and joule balances. However it does not contain a review of existing balances; this was a deliberate decision, as a number of such review papers have been published in the past five years [3-7] and it was felt that it was not yet time for another. The first technique considered is that of gravimetry; the watt balance measures the weight Mg of a mass M , and to convert the measured weight into a mass, the value of the acceleration due to gravity g must be known, at the time of the weighing and at the centre of gravity of the mass. The paper by Liard and his co-authors at NRC describes how they have made this essential measurement. The accuracy of the watt balance may also depend on the alignment of the apparatus. Two papers deal with this important issue. The first, by Sanchez and his co-authors at NRC, shows that their balance is insensitive to a range of alignments and concentrates on the essential alignments that contribute directly to the overall uncertainty of the apparatus. Thomas and his co-authors at LNE describe their technique for reducing uncertainties in their watt balance by aligning its coil in the field of the magnet to minimize both horizontal forces and torques about horizontal axes. The search for discrepancies between the results from watt balances has encouraged researchers to consider possible error mechanisms arising from the secondary electrical interactions between the coil of a watt balance and other parts of the apparatus. Researchers from INRIM have two such papers: one considering magnetic interactions and the other considering electrostatic interactions. It is essential that such investigations are carried out: both to prove that the problems are understood and for the guidance of those building the next generation of watt and joule balances. The next four papers describe aspects of the construction of watt balances. The BIPM watt balance group describe the principles behind their simultaneous measurement scheme for a watt balance. The balance that they are constructing can also be used in the conventional two-phase mode and their paper describes the relative advantages and disadvantages of the two modes of operation. In a watt balance there are some advantages to precise vertical movement of the coil. The METAS group describe the two mechanisms that they have tested to achieve such motion and give the reasons for the choice of mechanism for use in the balance that they are constructing. The KRISS watt balance group are in the initial phases of the design and construction of a watt balance and their paper provides valuable information on the design that they are building. The design of the main magnet of a watt balance is critical to its successful operation, and an important assumption of watt balance operation is that the field of the magnet in moving mode is equivalent to that in weighing mode. Sutton and Clarkson from MSL describe a novel magnet which is designed to address this issue. The international prototype of the kilogram is kept in air but, after redefinition, the best realizations of the mass unit will be in vacuum. In their paper Berry and Davidson from NPL describe progress in techniques which relate mass measured in vacuum to that measured in air. Such techniques will be essential for making the results of watt and joule balance measurements available to science and industry. Both the NIST and NPL Mark II (NRC) watt balances use knife edges to act as the pivots for the beam. Knife edges suffer from hysteresis which can produce systematic offsets during weighing. In their paper Choi (KRISS) and Robinson (NPL) describe the analysis of this problem using both finite element (FEM) techniques and a stand-alone balance designed for testing knife edges. The last two papers deal with the possible future of the watt balance technique. The BIPM simultaneous measurement scheme for the watt balance was originally conceived for operation at cryogenic temperatures with a superconducting coil. In their paper de Mirandes and her co-authors describe initial work on the principles of this superconducting variant of the BIPM watt balance and concentrate on the characteristics of the superconducting coil in comparison with those of a normal coil. The final paper is a good example of serendipity in which Kibble (Independent Consultant) was designing novel watt balances based on seismometer suspensions and Robinson (NPL) had derived a set of general expressions, which are required for a watt balance to be immune to a range of common misalignments but also lead to the design of watt balances with a range of coil motions. The combination of these techniques has led to the novel watt balance designs which are described. Finally I would like to thank: the editor of Metrologia and the editorial staff of IOP Publishing, the referees who have responded rapidly to requests and have kept the issue on schedule, and the authors who have taken the time to provide a range of papers showing the breadth of the work required to build and operate watt or joule balances. References [1] Andreas B et al 2011 Determination of the Avogadro constant by counting the atoms in a 28Si crystal Phys. Rev. Lett. 106 030801 [2] BIPM 2013 Report of the 14th Meeting of the CCM Sèvres pp 34-7 [3] Steiner R 2013 History and progress on accurate measurements of the Planck constant Rep. Prog. Phys. 76 016101 [4] Stock M 2013 Watt balance experiments for the determination of the Planck constant and the redefinition of the kilogram Metrologia 50 R1-16 [5] Li S, Han B, Li Z and Lan J 2012 Precisely measuring the Planck constant by electromechanical balances Measurement 45 1-13 [6] Eichenberger A, Genevès G and Gournay P 2009 Determination of the Planck constant by means of a watt balance Eur. Phys. J. Spec. Top. 172 363-83 [7] Robinson I A 2009 Toward the redefinition of the kilogram: measurements of Planck's constant using watt balances IEEE Trans. Instrum. Meas. 58 942-8

Ventilation rates in recently constructed U.S. school classrooms.

PubMed

Batterman, S; Su, F-C; Wald, A; Watkins, F; Godwin, C; Thun, G

2017-09-01

Low ventilation rates (VRs) in schools have been associated with absenteeism, poorer academic performance, and teacher dissatisfaction. We measured VRs in 37 recently constructed or renovated and mechanically ventilated U.S. schools, including LEED and EnergyStar-certified buildings, using CO 2 and the steady-state, build-up, decay, and transient mass balance methods. The transient mass balance method better matched conditions (specifically, changes in occupancy) and minimized biases seen in the other methods. During the school day, air change rates (ACRs) averaged 2.0±1.3 hour -1 , and only 22% of classrooms met recommended minimum ventilation rates. HVAC systems were shut off at the school day close, and ACRs dropped to 0.21±0.19 hour -1 . VRs did not differ by building type, although cost-cutting and comfort measures resulted in low VRs and potentially impaired IAQ. VRs were lower in schools that used unit ventilators or radiant heating, in smaller schools and in larger classrooms. The steady-state, build-up, and decay methods had significant limitations and biases, showing the need to confirm that these methods are appropriate. Findings highlight the need to increase VRs and to ensure that energy saving and comfort measures do not compromise ventilation and IAQ. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

A LEGO Watt balance: An apparatus to determine a mass based on the new SI

NASA Astrophysics Data System (ADS)

Chao, L. S.; Schlamminger, S.; Newell, D. B.; Pratt, J. R.; Seifert, F.; Zhang, X.; Sineriz, G.; Liu, M.; Haddad, D.

2015-11-01

A global effort to redefine our International System of Units (SI) is underway, and the change to the new system is expected to occur in 2018. Within the newly redefined SI, the present base units will still exist but be derived from fixed numerical values of seven reference constants. In particular, the unit of mass (the kilogram) will be realized through a fixed value of the Planck constant h. A so-called watt balance, for example, can then be used to realize the kilogram unit of mass within a few parts in 108. Such a balance has been designed and constructed at the National Institute of Standards and Technology. For educational outreach and to demonstrate the principle, we have constructed a LEGO tabletop watt balance capable of measuring a gram-level masses to 1% relative uncertainty. This article presents the design, construction, and performance of the LEGO watt balance and its ability to determine h.

The effect of cane use on the compensatory step following posterior perturbations.

PubMed

Hall, Courtney D; Jensen, Jody L

2004-08-01

The compensatory step is a critical component of the balance response and is impaired in older fallers. The purpose of this research was to examine whether utilization of a cane modified the compensatory step response following external posterior perturbations. Single subject withdrawal design was employed. Single subject statistical analysis--the standard deviation bandwidth-method--supplemented visual analysis of the data. Four older adults (range: 73-83 years) with balance impairment who habitually use a cane completed this study. Subjects received a series of sudden backward pulls that were large enough to elicit compensatory stepping. We examined the following variables both with and without cane use: timing of cane loading relative to step initiation and center of mass acceleration, stability margin, center of mass excursion and velocity, step length and width. No participant loaded the cane prior to initiation of the first compensatory step. There was no effect of cane use on the stability margin, nor was there an effect of cane use on center of mass excursion or velocity, or step length or width. These data suggest that cane use does not necessarily improve balance recovery following an external posterior perturbation when the individual is forced to rely on compensatory stepping. Instead these data suggest that the strongest factor in modifying step characteristics is experience with the perturbation.

Kinetic studies on batch cultivation of Trichoderma reesei and application to enhance cellulase production by fed-batch fermentation.

PubMed

Ma, Lijuan; Li, Chen; Yang, Zhenhua; Jia, Wendi; Zhang, Dongyuan; Chen, Shulin

2013-07-20

Reducing the production cost of cellulase as the key enzyme for cellulose hydrolysis to fermentable sugars remains a major challenge for biofuel production. Because of the complexity of cellulase production, kinetic modeling and mass balance calculation can be used as effective tools for process design and optimization. In this study, kinetic models for cell growth, substrate consumption and cellulase production in batch fermentation were developed, and then applied in fed-batch fermentation to enhance cellulase production. Inhibition effect of substrate was considered and a modified Luedeking-Piret model was developed for cellulase production and substrate consumption according to the growth characteristics of Trichoderma reesei. The model predictions fit well with the experimental data. Simulation results showed that higher initial substrate concentration led to decrease of cellulase production rate. Mass balance and kinetic simulation results were applied to determine the feeding strategy. Cellulase production and its corresponding productivity increased by 82.13% after employing the proper feeding strategy in fed-batch fermentation. This method combining mathematics and chemometrics by kinetic modeling and mass balance can not only improve cellulase fermentation process, but also help to better understand the cellulase fermentation process. The model development can also provide insight to other similar fermentation processes. Copyright © 2013 Elsevier B.V. All rights reserved.

Spent Nuclear Fuel (SNF) Project Canister Storage Building (CSB) Process Flow Diagram Mass Balance Calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

KLEM, M.J.

2000-05-11

The purpose of these calculations is to develop the material balances for documentation of the Canister Storage Building (CSB) Process Flow Diagram (PFD) and future reference. The attached mass balances were prepared to support revision two of the PFD for the CSB. The calculations refer to diagram H-2-825869.

A Mass Balance-Based Semiparametric Approach to Evaluate Neonatal Erythropoiesis.

PubMed

Kuruvilla, Denison J; Widness, John A; Nalbant, Demet; Schmidt, Robert L; Mock, Donald M; Veng-Pedersen, Peter

2016-01-01

Postnatal hemoglobin (Hb) production in anemic preterm infants is determined by several factors including the endogenous erythropoietin levels, allogeneic RBC transfusions administered to treat anemia, and developmental age. As a result, their postnatal Hb production rate can vary considerably. This work introduces a novel Hb mass balance-based semiparametric approach that utilizes infant blood concentrations of Hb from the first 30 postnatal days to estimate the amount of Hb produced and the erythropoiesis rate in newborn infants. The proposed method has the advantage of not relying on specific structural pharmacodynamic model assumptions to describe the Hb production, but instead utilizes simple mass balance principles and nonparametric regression analysis. The developed method was applied to the Hb data from 79 critically ill anemic very low birth weight preterm infants to evaluate the dynamic changes in erythropoiesis during the first month of life and to determine the inter-subject variability in Hb production. The estimated mean (±SD) cumulative amount of Hb produced by the infants over the first month of life was 6.6 ± 3.4 g (mean body weight, 0.768 kg), and the mean estimated body weight-scaled Hb production rate over the same period was 0.23 ± 0.12 g/day/kg. A significant positive correlation was observed between infant gestational age and the mean body weight-scaled Hb production rate over the first month of life (P < 0.05). We conclude that the proposed mathematical approach and its implementation provide a flexible framework to evaluate postnatal erythropoiesis in newborn infants.

Stabilised finite-element methods for solving the level set equation with mass conservation

NASA Astrophysics Data System (ADS)

Kabirou Touré, Mamadou; Fahsi, Adil; Soulaïmani, Azzeddine

2016-01-01

Finite-element methods are studied for solving moving interface flow problems using the level set approach and a stabilised variational formulation proposed in Touré and Soulaïmani (2012; Touré and Soulaïmani To appear in 2016), coupled with a level set correction method. The level set correction is intended to enhance the mass conservation satisfaction property. The stabilised variational formulation (Touré and Soulaïmani 2012; Touré and Soulaïmani, To appear in 2016) constrains the level set function to remain close to the signed distance function, while the mass conservation is a correction step which enforces the mass balance. The eXtended finite-element method (XFEM) is used to take into account the discontinuities of the properties within an element. XFEM is applied to solve the Navier-Stokes equations for two-phase flows. The numerical methods are numerically evaluated on several test cases such as time-reversed vortex flow, a rigid-body rotation of Zalesak's disc, sloshing flow in a tank, a dam-break over a bed, and a rising bubble subjected to buoyancy. The numerical results show the importance of satisfying global mass conservation to accurately capture the interface position.

On the predictability of protein database search complexity and its relevance to optimization of distributed searches.

PubMed

Deciu, Cosmin; Sun, Jun; Wall, Mark A

2007-09-01

We discuss several aspects related to load balancing of database search jobs in a distributed computing environment, such as Linux cluster. Load balancing is a technique for making the most of multiple computational resources, which is particularly relevant in environments in which the usage of such resources is very high. The particular case of the Sequest program is considered here, but the general methodology should apply to any similar database search program. We show how the runtimes for Sequest searches of tandem mass spectral data can be predicted from profiles of previous representative searches, and how this information can be used for better load balancing of novel data. A well-known heuristic load balancing method is shown to be applicable to this problem, and its performance is analyzed for a variety of search parameters.

Kinetics of inactivation and dilution effects on the mass balance of fungal phytopathogens in anaerobic digesters.

PubMed

Plöchl, Matthias; Heiermann, Monika; Rodemann, Bernd; Bandte, Martina; Büttner, Carmen

2014-01-15

Knowledge of fate and behavior of plant pathogens in the biogas production chain is limited and hampers the estimation and evaluation of the potential phytosanitary risk if digestate is spread on arable land as a fertilizer. Therefore, simulation is an appropriate tool to demonstrate the effects which influence the steady state of pathogen infected plant material in both digesters and digestate. Simple approaches of kinetics of inactivation and mass balances of infected material were carried out considering single-step as well as two-step digestion. The simulation revealed a very fast to fast reduction of infected material after a singular feeding, reaching a cutback to less than 1% of input within 4 days even for D90-values of 68 h. Steady state mass balances below input rate could be calculated with D90-values of less than 2 h at a continuous hourly feeding. At higher D90-values steady state mass balances exceed the input rate but are still clearly below the sum of input mass. Dilution further decreases mass balances to values 10(-5) to 10(-6) Mg m(-3) for first-step digestion and 10(-8) to 10(-9) for second-step. Copyright © 2013 Elsevier Ltd. All rights reserved.

Active balance system and vibration balanced machine

NASA Technical Reports Server (NTRS)

White, Maurice A. (Inventor); Qiu, Songgang (Inventor); Augenblick, John E. (Inventor); Peterson, Allen A. (Inventor)

2005-01-01

An active balance system is provided for counterbalancing vibrations of an axially reciprocating machine. The balance system includes a support member, a flexure assembly, a counterbalance mass, and a linear motor or an actuator. The support member is configured for attachment to the machine. The flexure assembly includes at least one flat spring having connections along a central portion and an outer peripheral portion. One of the central portion and the outer peripheral portion is fixedly mounted to the support member. The counterbalance mass is fixedly carried by the flexure assembly along another of the central portion and the outer peripheral portion. The linear motor has one of a stator and a mover fixedly mounted to the support member and another of the stator and the mover fixedly mounted to the counterbalance mass. The linear motor is operative to axially reciprocate the counterbalance mass.

Solar radiation, cloudiness and longwave radiation over low-latitude glaciers: implications for mass-balance modelling

NASA Astrophysics Data System (ADS)

Mölg, Thomas; Cullen, Nicolas J.; Kaser, Georg

Broadband radiation schemes (parameterizations) are commonly used tools in glacier mass-balance modelling, but their performance at high altitude in the tropics has not been evaluated in detail. Here we take advantage of a high-quality 2 year record of global radiation (G) and incoming longwave radiation (L↓) measured on Kersten Glacier, Kilimanjaro, East Africa, at 5873 m a.s.l., to optimize parameterizations of G and L↓. We show that the two radiation terms can be related by an effective cloud-cover fraction neff, so G or L↓ can be modelled based on neff derived from measured L↓ or G, respectively. At neff = 1, G is reduced to 35% of clear-sky G, and L↓ increases by 45-65% (depending on altitude) relative to clear-sky L↓. Validation for a 1 year dataset of G and L↓ obtained at 4850 m on Glaciar Artesonraju, Peruvian Andes, yields a satisfactory performance of the radiation scheme. Whether this performance is acceptable for mass-balance studies of tropical glaciers is explored by applying the data from Glaciar Artesonraju to a physically based mass-balance model, which requires, among others, G and L↓ as forcing variables. Uncertainties in modelled mass balance introduced by the radiation parameterizations do not exceed those that can be caused by errors in the radiation measurements. Hence, this paper provides a tool for inclusion in spatially distributed mass-balance modelling of tropical glaciers and/or extension of radiation data when only G or L↓ is measured.

40 CFR 98.174 - Monitoring and QA/QC requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... emissions using the carbon mass balance procedure in § 98.173(b)(1), you must: (1) Except as provided in... Standard Test Methods for Instrumental Determination of Carbon, Hydrogen, and Nitrogen in Laboratory... Carbon, Sulfur, Nitrogen, and Oxygen in Steel, Iron, Nickel, and Cobalt Alloys by Various Combustion and...

40 CFR 98.174 - Monitoring and QA/QC requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... emissions using the carbon mass balance procedure in § 98.173(b)(1), you must: (1) Except as provided in... Standard Test Methods for Instrumental Determination of Carbon, Hydrogen, and Nitrogen in Laboratory... Carbon, Sulfur, Nitrogen, and Oxygen in Steel, Iron, Nickel, and Cobalt Alloys by Various Combustion and...

40 CFR 98.174 - Monitoring and QA/QC requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... emissions using the carbon mass balance procedure in § 98.173(b)(1), you must: (1) Except as provided in... Standard Test Methods for Instrumental Determination of Carbon, Hydrogen, and Nitrogen in Laboratory... Carbon, Sulfur, Nitrogen, and Oxygen in Steel, Iron, Nickel, and Cobalt Alloys by Various Combustion and...

40 CFR 98.244 - Monitoring and QA/QC requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

... procedures specified in § 98.34(c). (b) If you use the mass balance methodology in § 98.243(c), use the... Test Methods for Instrumental Determination of Carbon, Hydrogen, and Nitrogen in Petroleum Products and... Instrumental Determination of Carbon, Hydrogen, and Nitrogen in Laboratory Samples of Coal (incorporated by...

40 CFR 98.174 - Monitoring and QA/QC requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

... emissions using the carbon mass balance procedure in § 98.173(b)(1), you must: (1) Except as provided in... Methods for Instrumental Determination of Carbon, Hydrogen, and Nitrogen in Laboratory Samples of Coal..., Nitrogen, and Oxygen in Steel, Iron, Nickel, and Cobalt Alloys by Various Combustion and Fusion Techniques...

40 CFR 98.244 - Monitoring and QA/QC requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

... procedures specified in § 98.34(c). (b) If you use the mass balance methodology in § 98.243(c), use the...) Standard Test Methods for Instrumental Determination of Carbon, Hydrogen, and Nitrogen in Petroleum... for Instrumental Determination of Carbon, Hydrogen, and Nitrogen in Laboratory Samples of Coal...

Disseminating the unit of mass from multiple primary realisations

NASA Astrophysics Data System (ADS)

Nielsen, Lars

2016-12-01

When a new definition of the kilogram has been adopted in 2018 as expected, the unit of mass will be realised by the watt balance method, the x-ray crystal density method or perhaps other primary methods still to be developed. So far, the standard uncertainties associated with the available primary methods are at least one order of magnitude larger than the standard uncertainty associated with mass comparisons using mass comparators, so differences in primary realisations of the kilogram are easily detected, whereas many National Metrology Institutes would have to increase their calibration and measurement capabilities (CMCs) if they were traceable to a single primary realisation. This paper presents a scheme for obtaining traceability to multiple primary realisations of the kilogram using a small group of stainless steel 1 kg weights, which are allowed to change their masses over time in a way known to be realistic, and which are calibrated and stored in air. An analysis of the scheme shows that if the relative standard uncertainties of future primary realisations are equal to the relative standard uncertainties of the present methods used to measure the Planck constant, the unit of mass can be disseminated with a standard uncertainty less than 0.015 mg, which matches the smallest CMCs currently claimed for the calibration of 1 kg weights.

Bioanalysis works in the IAA AMS facility: Comparison of AMS analytical method with LSC method in human mass balance study

NASA Astrophysics Data System (ADS)

Miyaoka, Teiji; Isono, Yoshimi; Setani, Kaoru; Sakai, Kumiko; Yamada, Ichimaro; Sato, Yoshiaki; Gunji, Shinobu; Matsui, Takao

2007-06-01

Institute of Accelerator Analysis Ltd. (IAA) is the first Contract Research Organization in Japan providing Accelerator Mass Spectrometry (AMS) analysis services for carbon dating and bioanalysis works. The 3 MV AMS machines are maintained by validated analysis methods using multiple control compounds. It is confirmed that these AMS systems have reliabilities and sensitivities enough for each objective. The graphitization of samples for bioanalysis is prepared by our own purification lines including the measurement of total carbon content in the sample automatically. In this paper, we present the use of AMS analysis in human mass balance and metabolism profiling studies with IAA 3 MV AMS, comparing results obtained from the same samples with liquid scintillation counting (LSC). Human samples such as plasma, urine and feces were obtained from four healthy volunteers orally administered a 14C-labeled drug Y-700, a novel xanthine oxidase inhibitor, of which radioactivity was about 3 MBq (85 μCi). For AMS measurement, these samples were diluted 100-10,000-fold with pure-water or blank samples. The results indicated that AMS method had a good correlation with LSC method (e.g. plasma: r = 0.998, urine: r = 0.997, feces: r = 0.997), and that the drug recovery in the excreta exceeded 92%. The metabolite profiles of plasma, urine and feces obtained with HPLC-AMS corresponded to radio-HPLC results measured at much higher radioactivity level. These results revealed that AMS analysis at IAA is useful to measure 14C-concentration in bioanalysis studies at very low radioactivity level.

Recent Innovations in Monitoring Suspended-Sediment Mass Balance of the Colorado River Ecosystem Below Glen Canyon Dam: A laser-Based Approach

NASA Astrophysics Data System (ADS)

Melis, T. S.; Topping, D. J.; Rubin, D. M.; Agrawal, Y. C.

2002-12-01

Intensive monitoring of suspended-sediment in the Colorado River ecosystem below Glen Canyon Dam is a priority for environmental management. Historically, the program has been logistically complicated, costly and limited in spatial and temporal resolution. These elements have contributed to relatively large uncertainties in mass-balance estimates of sediment export. To improve mass-balance estimates, the Grand Canyon Monitoring and Research Center is field testing new and existing technologies to develop a continuous suspended-sediment transport protocol. A recent innovation includes use of optical forward-scattering instruments, LISST, in combination with programmable pumping samplers. The LISST-100 (Laser In-Situ Scattering and Transmissometry) is both a particle-size analyzer (size range 2.5 to 500 microns) and a transmissometer capable of measuring variable concentrations, depending on particle size. A second innovation, the LISST-25X, is a recently developed variation of the instrumentation that allows sand to be measured separately from finer particles. This is achieved by use of shaped focal plane detectors that compute 2 distinct weighted sums of angular scattering by suspended particles. The LISST-25X currently collects volume-concentration and grain size (Sauter-mean-diameter) data for suspended particles at four sites below the dam. Unit values are derived by averaging 1000 individual measurements every 15-minutes (sampling about 1.1 liters of water per hour). The volume-to-mass conversion is made once average particle density has been gravimetrically determined through conventional methods. During high-concentration conditions, laser-transmission values (T) can fall outside of the user-defined minimal threshold (20

Glaciers of Europe

USGS Publications Warehouse

Williams, Richard S.; Ferrigno, Jane G.

1993-01-01

ALPS: AUSTRIAN: An overview is provided on the occurrence of the glaciers in the Eastern Alps of Austria and on the climatic conditions in this area, Historical documents on the glaciers have been available since the Middle Ages. Special glaciological observations and topographic surveys of individual glaciers were initiated as early as 1846. Recent data in an inventory based on aerial photographs taken in 1969 show 925 glaciers in the Austrian Alps with a total area of 542 square kilometers. Present research topics include studies of mass and energy balance, relations of glaciers and climate, physical glaciology, a complete inventory of the glaciers, and testing of remote sensing methods. The location of the glacier areas is shown on Landsat multispectral scanner images; the improved capabilities of the Landsat thematic mapper are illustrated with an example from the Oztaler Alpen group. ALPS: SWISS: According to a glacier inventory published in 1976, which is based on aerial photography of 1973, there are 1,828 glacier units in the Swiss Alps that cover a total area of 1fl42 square kilometers. The Rhonegletscher, currently the ninth largest in the country, was one of the first to be studied in detail. Its surface has been surveyed repeatedly; velocity profiles were measured, and the fluctuations of its terminus were mapped and recorded from 1874 to 1914. Recent research on the glacier has included climatological, hydrological, and massbalance studies. Glaciological research has been conducted on various other glaciers in Switzerland concerning glacier hydrology, glacier hazards, fluctuations of glacier termini, ice mechanics, ice cores, and mass balance. Good maps are available showing the extent of glaciers from the latter decades of the 19th century. More recently, the entire country has been mapped at scales of 1:25,000, 1:50,000, 1:100,000, 1:200,000, and 1:500,000. The 1:25,000-scale series very accurately represents the glaciers as well as locates supraglacial morainic debris and crevasses. The maps are revised every 6 years by use of aerial photogrammetric methods. The possibility of producing a glacier inventory by combining the topographic maps with Landsat digital and visual data is discussed. ALPS: FRENCH: The glaciers of the French Alps are distributed in four main groups and have a total area of 350 square kilometers. The northernmost group, on the Mont Blanc massif, has a glacier area of 110 square kilometers, which includes Met de Glace, which, with an area of 40 square kilometers, is the largest glacier in the Western Alps. Farther south, the Massif de la Vanoise contains 130 glaciers that have a total area of 85 square kilometers. The glaciers of the Grandes Rousses massif have a total area of 11 square kilometers. Lastly, the Massif du Pelvoux has a total glacier area of 120 square kilometers. Studies of glacier variations since 1600 A.D. have shown numerous fluctuations in glacier length. The glaciers on Mont Blanc that appear to show similar fluctuations in fact have different individual response times. Mass-balance measurements are presently being carried out on nine glaciers. The measurements on one of these glaciers, Glacier de Saint Sorlin, have been used to validate a linear statistical model for mass-balance variation. The model seems to give good results when extended over the entire region of French Alpine glaciers. New methods of mass-balance reconstructions by use of a continuity equation are discussed. Current satellite data have limited usefulness for glacier studies in the French Alps, with the exception of the method correlating changes in the elevation of snowline to changes in glacier mass balance. ALPS: ITALIAN: Research carried out by Italian glaciologists in support of the World Glacier Inventory project identified approximately 1,400 glaciers in the mountain groups of the Italian Alps. The total surface area of all glaciers, glacierets, and permanent snow fields in Italy with

Inertial Mass

ERIC Educational Resources Information Center

King, Kenneth P.

2007-01-01

The inertial balance is one device that can help students to quantify the quality of inertia--a body's resistance to a change in movement--in more generally understood terms of mass. In this hands-on activity, students use the inertial balance to develop a more quantitative idea of what mass means in an inertial sense. The activity also helps…

Quantifying the resolution level where the GRACE satellites can separate Greenland's glacial mass balance from surface mass balance

NASA Astrophysics Data System (ADS)

Bonin, J. A.; Chambers, D. P.

2015-09-01

Mass change over Greenland can be caused by either changes in the glacial dynamic mass balance (DMB) or the surface mass balance (SMB). The GRACE satellite gravity mission cannot directly separate the two physical causes because it measures the sum of the entire mass column with limited spatial resolution. We demonstrate one theoretical way to indirectly separate cumulative SMB from DMB with GRACE, using a least squares inversion technique with knowledge of the location of the glaciers. However, we find that the limited 60 × 60 spherical harmonic representation of current GRACE data does not provide sufficient resolution to adequately accomplish the task. We determine that at a maximum degree/order of 90 × 90 or above, a noise-free gravity measurement could theoretically separate the SMB from DMB signals. However, current GRACE satellite errors are too large at present to separate the signals. A noise reduction of a factor of 10 at a resolution of 90 × 90 would provide the accuracy needed for the interannual cumulative SMB and DMB to be accurately separated.

Quantifying the resolution level where the GRACE satellites can separate Greenland's glacial mass balance from surface mass balance

NASA Astrophysics Data System (ADS)

Bonin, J. A.; Chambers, D. P.

2015-02-01

Mass change over Greenland can be caused by either changes in the glacial mass balance (GMB) or the precipitation-based surface mass balance (SMB). The GRACE satellite gravity mission cannot directly separate the two physical causes because it measures the sum of the entire mass column with limited spatial resolution. We demonstrate one theoretical way to indirectly separate SMB from GMB with GRACE, using a least squares inversion technique with knowledge of the location of the glacier. However, we find that the limited 60 × 60 spherical harmonic representation of current GRACE data does not provide sufficient resolution to adequately accomplish the task. We determine that at a maximum degree/order of 90 × 90 or above, a noise-free gravity measurement could theoretically separate the SMB from GMB signals. However, current GRACE satellite errors are too large at present to separate the signals. A noise reduction of a factor of 9 at a resolution of 90 × 90 would provide the accuracy needed for the interannual SMB and GMB to be accurately separated.

Regionally Optimized GRACE Processing and Inter-comparison on the Antarctic Ice Sheet

NASA Astrophysics Data System (ADS)

Mohajerani, Y.; Velicogna, I.; Sutterley, T. C.; Rignot, E. J.

2017-12-01

The Antarctic ice sheet is losing mass at an accelerating rate, with a sea level contribution that changed from 0.08mm/yr from 1992 to 2001 to 0.4mm/yr from 2002 to 2011. While most of this contribution comes from West Antarctica, Totten Glacier has the largest discharge of ice in East Antarctica, with a sea level rise potential of 3.9 m. Furthermore, the drainage basin of Totten Glacier, along the neighboring Moscow University Glacier are below sea level, extending hundreds of kilometers inland. Therefore, obtaining regional estimates of both western and eastern Antarctic basins are of critical importance. The GRACE (Gravity Recovery and Climate Experiment) satellite has been providing mass balance time-series from geoid changes since 2002. Several mascon and harmonic GRACE solutions are available from different processing centers. Here, we evaluate the various solutions across the ice sheet and a new set of regionally optimized mascons to study the mass balance of Totten and Moscow University glaciers. We obtain a trend of -16.5±4.1Gt/yr with an acceleration of -2.0±1.8Gt/yr2 for the two glaciers for the period April 2002 to December 2016 using the Ivins et al (2013) GIA model (errors include leakage, GIA, and regression errors). We compare the results with the Mass Budget Method that combines ice discharge (D) and surface mass balance (SMB) from two models: 1) RACMO2.3, and 2) MAR3.6.4. MBM/RACMO2.3 shows the best agreement with the GRACE estimates. Within the common period from April 2002 to December 2015, the MBM/RACMO2.3 and MAR3.6.4 results are -15.6±1.8Gt/yr and -6.7±1.5Gt/yr respectively, while the GRACE time-series has a trend of -14.8±2.7 Gt/yr. We extend the study to the Getz Ice Shelf, the third largest ice shelf in West Antarctica after Ronne and Ross West ice shelves. We compare our gravity-derived mass estimates, the mass budget estimates, and the volume changes from altimetry data to compare the estimates and obtain a multi-sensor assessment of ice sheet mass balance.

Changes in ice dynamics along the northern Antarctic Peninsula

NASA Astrophysics Data System (ADS)

Seehaus, Thorsten; Marinsek, Sebastian; Cook, Alison; Van Wessem, Jan-Melchior; Braun, Matthias

2017-04-01

The climatic conditions along the Antarctic Peninsula have undergone considerable changes during the last 50 years. A period of pronounced air temperature rise, increasing ocean temperatures as well as changes in the precipitation pattern have been reported by various authors. Consequently, the glacial systems showed changes including widespread retreat, surface lowering as well as variations in flow speeds. During the last decades numerous ice shelves along the Antarctic Peninsula retreated, started to break-up or disintegrated completely. The loss of the buttressing effect caused tributary glaciers to accelerate with increasing ice discharge along the Antarctic Peninsula. Quantification of the mass changes is still subject to considerable errors although numbers derived from the different methods are converging. The aim is to study the reaction of glaciers at the northern Antarctic Peninsula to the changing climatic conditions and the readjustments of tributary glaciers to ice shelf disintegration, as well as to better quantify the ice mass loss and its temporal changes. We analysed time series of various satellite sensors (ERS-1/2 SAR, ENVISAT ASAR, RADARSAT-1, ALOS PALSAR, TerraSAR-X/TanDEM-X, ASTER, Landsat) to detect changes in ice dynamics of 74 glacier basins along the northern Antarctic Peninsula (<65°). Intensity feature tracking techniques were applied on data stacks from different SAR satellites over the last 20 years to infer temporal trends in glacier surface velocities. In combination with ice thickness reconstructions and modeled climatic mass balance fields regional imbalances were calculated. Variations in ice front position were mapped based on optical and SAR satellite data sets. Along the west coast of the northern Antarctic Peninsula an increase in flow speeds by 40% between 1992 and 2014 was observed, whereas glaciers on the east side (north of former Prince-Gustav Ice Shelf) showed a strong deceleration. Nearly all former ice shelf tributaries showed similar reactions to ice shelf disintegration, with a significant acceleration and frontal retreat after ice shelf break-up and a subsequent deceleration and front stabilization. In total an ice discharge of 17.93±6.22 Gt/a was estimated for the study region in the period 2010-2014. Regional mass balance estimates indicate nearly balanced mass budgets in the period 1992-1996 and positive imbalances in more recent years (2010-2014), dominated by the clearly positive mass balances along the west coast due to high climatic mass balances. The detailed multi-mission time series analysis of glacier changes supports the interpretation of the ongoing processes in this region and allows multi temporal imbalance estimates.

Balance Confidence Improves with Resistance or Agility training: Increase is not Correlated with Objective Changes in Fall Risk and Physical Abilities

PubMed Central

Liu-Ambrose, Teresa; Khan, Karim M; Eng, Janice J; Lord, SR; McKay, HA

2012-01-01

Background While the fear of falling is a common psychological consequence of falling, older adults who have not fallen also frequently report this fear. Fear of falling can lead to activity restriction that is self-imposed rather than due to actual physical impairments. Evidence suggests that exercise can significantly improve balance confidence, as measured by falls-related self-efficacy scales. However, there are no prospective reports that correlate change in balance confidence with changes in fall risk and physical abilities as induced by participating in a group-based exercise program. Objective The primary purpose of this prospective study was to examine the relationship between the change in balance confidence and the changes in fall risk and physical abilities in older women with confirmed low bone mass after 13 weeks of exercise participation. The secondary purpose of this study was to examine the relationship between the change in balance confidence and the change in physical activity level. Methods The sample comprised 98 women aged 75 to 85 years old women with low bone mass. Participants were randomly assigned to one of three groups: Resistance Training (n=32), Agility Training (n=34), and Stretching (sham) exercises (n=32). The 50-minute exercise classes for each study arm were held twice weekly at a local YMCA community centre. Results Both resistance training and agility training significantly improved balance confidence by 6% from baseline after 13 weeks. However, the change in balance confidence was only weakly correlated with improved general physical function and not significantly correlated with the changes in fall risk score, postural stability, gait speed, or physical activity level. As well, we observed balance confidence enhancement in the presence of increased fall risk or deterioration in physical abilities. Conclusions Two different types of exercise training improved balance confidence in older women with low bone mass. This change in balance confidence was significantly correlated with change in general physical function. Because of the observation of discordance between balance confidence change and changes in fall risk and physical abilities, those who design group-based exercise programs for community-dwelling older adults may wish to consider including an education component on factors that influence fear of falling. Objective changes in fall risk factors cannot be assumed to mirror change of fear of falling and physical abilities in older adults in the short-term. PMID:15477698

Critical discussion on the "observed" water balances of five sub-basins in the Everest region

NASA Astrophysics Data System (ADS)

Chevallier, P.; Eeckman, J.; Nepal, S.; Delclaux, F.; Wagnon, P.; Brun, F.; Koirala, D.

2017-12-01

The hydrometeorological components of five Dudh Koshi River sub-basins on the Nepalese side of the Mount Everest have been monitored during four hydrological years (2013-2017), with altitudes ranging from 2000 m to Everest top, areas between 4.65 and 1207 km², and proportions of glaciated areas between nil and 45%. This data set is completed with glacier mass balance observations. The analysis of the observed data and the resulting water balances show large uncertainties of different types: aleatory, epistemic or semantic, following the classification proposed by Beven (2016). The discussion is illustrated using results from two modeling approaches, physical (ISBA, Noilhan and Planton, 1996) and conceptual (J2000, Krause, 2001), as well as large scale glacier mass balances obtained by the way of a recent remote sensing processing method. References: Beven, K., 2016. Facets of uncertainty: epistemic uncertainty, non-stationarity, likelihood, hypothesis testing, and communication. Hydrological Sciences Journal 61, 1652-1665. doi:10.1080/02626667.2015.1031761 Krause, P., 2001. Das hydrologische Modellsystem J2000: Beschreibung und Anwendung in groen Flueinzugsgebieten, Schriften des Forschungszentrum Jülich. Reihe Umwelt/Environment; Band 29. Noilhan, J., Planton, S., 1989. A single parametrization of land surface processes for meteorological models. Monthly Weather Review 536-549.

Evaluation of the Wii Balance Board for Walking Aids Prediction: Proof-of-Concept Study in Total Knee Arthroplasty

PubMed Central

Pua, Yong-Hao; Clark, Ross A.; Ong, Peck-Hoon

2015-01-01

Background and Objectives To provide proof-of-concept for the validity of the Wii Balance Board (WBB) measures to predict the type of walking aids required by inpatients with a recent (≤4days) total knee arthroplasty (TKA). Methods A cross-sectional sample of 89 inpatients (mean age, 67.0±8years) with TKA was analyzed. A multivariable proportional odds prediction model was constructed using 8 pre-specified predictors – namely, age, sex, body mass index, knee pain, knee range-of-motion, active knee lag, and WBB-derived standing balance. The type of walking aids prescribed on day 4 post-surgery was the outcome of interest – an ordinal variable with 4 categories (walking stick, narrow- and broad-base quadstick, and walking frame). Results Women, increasing body mass index, and poorer standing balance were independently associated with greater odds for requiring walking aids with a larger base-of-support. The concordance-index of the prediction model was 0.74. The model comprising only WBB-derived standing balance had nearly half (44%) the explanatory power of the full model. Adding WBB-derived standing balance to conventional demographic and knee variables resulted in a continuous net reclassification index of 0.60 (95%CI,0.19-1.01), predominantly due to better identification of patients who required walking aids with a large base-of-support (sensitivity gain). Conclusions The WBB was able to provide quantitative measures of standing balance which could assist healthcare professionals in prescribing the appropriate type of walking aids for patients. Further investigation is needed to assess whether using the WBB could lead to meaningful changes in clinical outcomes such as falls. PMID:25615952

Isostasy for Geoscience Labs.

ERIC Educational Resources Information Center

Diecchio, Richard Joseph

1995-01-01

Presents simple laboratory experiments to help students understand the principle of buoyancy and mass balance. Buoyancy experiments can simulate lithospheric mass balance, crustal loading and unloading, and can be used to model differences between the oceanic and continental lithosphere. (MKR)

Association of Body Mass Index With Self-Report and Performance-Based Measures of Balance and Mobility

PubMed Central

Wert, David M.; Hile, Elizabeth S.; Studenski, Stephanie A.; Brach, Jennifer S.

2011-01-01

Background The incidence of obesity is increasing in older adults, with associated worsening in the burden of disability. Little is known about the impact of body mass index (BMI) on self-report and performance-based balance and mobility measures in older adults. Objective The purposes of this study were (1) to examine the association of BMI with measures of balance and mobility and (2) to explore potential explanatory factors. Design This was a cross-sectional, observational study. Methods Older adults (mean age=77.6 years) who participated in an ongoing observational study (N=120) were classified as normal weight (BMI=18.5–24.9 kg/m2), overweight (BMI=25.0–29.9 kg/m2), moderately obese (BMI=30.0–34.9 kg/m2), or severely obese (BMI≥35 kg/m2). Body mass index data were missing for one individual; thus, data for 119 participants were included in the analysis. Mobility and balance were assessed using self-report and performance-based measures and were compared among weight groups using analysis of variance and chi-square analysis for categorical data. Multiple linear regression analysis was used to examine the association among BMI, mobility, and balance after controlling for potential confounding variables. Results Compared with participants who were of normal weight or overweight, those with moderate or severe obesity were less likely to report their mobility as very good or excellent (52%, 55%, 39%, and 6%, respectively); however, there was no difference in self-report of balance among weight groups. Participants with severe obesity (n=17) had the lowest levels of mobility on the performance-based measures, followed by those who were moderately obese (n=31), overweight (n=42), and of normal weight (n=29). There were no differences on performance-based balance measures among weight groups. After controlling for age, sex, minority status, physical activity level, education level, and comorbid conditions, BMI still significantly contributed to mobility (β=−.02, adjusted R2=.41). Conclusions Although older adults with severe obesity were most impaired, those with less severe obesity also demonstrated significant decrements in mobility. PMID:21680770

An ultra-accurate numerical method in the design of liquid phononic crystals with hard inclusion

NASA Astrophysics Data System (ADS)

Li, Eric; He, Z. C.; Wang, G.; Liu, G. R.

2017-12-01

The phononics crystals (PCs) are periodic man-made composite materials. In this paper, a mass-redistributed finite element method (MR-FEM) is formulated to study the wave propagation within liquid PCs with hard inclusion. With a perfect balance between stiffness and mass in the MR-FEM model, the dispersion error of longitudinal wave is minimized by redistribution of mass. Such tuning can be easily achieved by adjusting the parameter r that controls the location of integration points of mass matrix. More importantly, the property of mass conservation in the MR-FEM model indicates that the locations of integration points inside or outside the element are immaterial. Four numerical examples are studied in this work, including liquid PCs with cross and circle hard inclusions, different size of inclusion and defect. Compared with standard finite element method, the numerical results have verified the accuracy and effectiveness of MR-FEM. The proposed MR-FEM is a unique and innovative numerical approach with its outstanding features, which has strong potentials to study the stress wave within multi-physics PCs.

Changes in the Mass Balance of the Greenland Ice Sheet in a Warming Climate During 2003-2009

NASA Technical Reports Server (NTRS)

Zwally, H. Jay; Luthcke, Scott

2010-01-01

Mass changes of the Greenland ice sheet (GIS) derived from ICESat and GRACE data both show that the net mass loss from GIS during 2003-2009 is about 175 Gt/year, which contributes 0.5mm/yr global sea-level rise. The rate of mass loss has increased significantly since the 1990's when the GIS was close to mass balance. Even though the GIS was close to mass balance during the 1990's, it was already showing characteristics of responding to8 warmer climate, specifically thinning at the margins and thickening inland at higher elevations. During 2003-2009, increased ice thinning due to increases in melting and acceleration of outlet glaciers began to strongly exceed the inland thickening from increases in accumulation. Over the entire GIS, the mass loss between the two periods, from increased melting and ice dynamics, increased by about 190 Gt/year while the mass gain, from increased precipitation and accumulation, increased by only about 15Gt/year. These ice changes occurred during a time when the temperature on GIS changed at rate of about 2K/decade. The distribution of elevation and mass changes derived from ICESat have high spatial resolution showing details over outlet glaciers, by drainage systems, and by elevation. However, information on the seasonal cycle of changes from ICESat data is limited, because the ICESat lasers were only operated during two to three campaigns per year of about 35 days duration each. In contrast, the temporal resolution of GRACE data, provided by the continuous data collection, is much better showing details of the seasonal cycle and the inter-annual variability. The differing sensitivity of the ICESat altimetry and the GRACE gravity methods to motion of the underlying bedrock from glacial isostatic adjustment (GIA) is used to evaluate the GIA corrections provided by models. The two data types are also combined to make estimates of the partitioning of the mass gains and losses among accumulation, melting, and ice discharge from outlet glaciers.

A Simple Watt Balance for the Absolute Determination of Mass

ERIC Educational Resources Information Center

Quinn, Terry; Quinn, Lucas; Davis, Richard

2013-01-01

A watt balance is an electromechanical device that allows a mass to be determined in terms of measurable electrical and mechanical quantities, themselves traceable to the fundamental constants of physics. International plans are well advanced to redefine the unit of mass, the kilogram, in terms of a fixed numerical value for the Planck constant. A…

Mass Balance. Operational Control Tests for Wastewater Treatment Facilities. Instructor's Manual [and] Student Workbook.

ERIC Educational Resources Information Center

Carnegie, John W.

This module describes the process used to determine solids mass and location throughout a waste water treatment plant, explains how these values are used to determine the solids mass balance around single treatment units and the entire system, and presents calculations of solids in pounds and sludge units. The instructor's manual contains a…

A better GRACE solution for improving the regional Greenland mass balance

NASA Astrophysics Data System (ADS)

Schrama, E.; Xu, Z.

2012-04-01

In most GRACE based researches, a variety of smoothing methods is employed to remove alternating bands of positive and negative stripes stretching in the north-south direction. Many studies have suggested to smooth the GRACE maps, on which mass variations are represented as equivalent water height (EWH). Such maps are capable of exposing the redistribution of earth surface mass over time. In Greenland the shrinking of the ice cap becomes significant in the last decade. Our present study confirms that the dominating melting trends are in the east and southeast coastal zones, however, the smoothed signals along the coastline in these areas do not represent the original but averaged measurements from GRACE satellites which means the signal strength indicating that negative mass variations are mixed with some positive signals that are very close to this area. An exact identification of the topographic edge is not possible and visually the EWH maps appear to be blurred. To improve this, we firstly used spherical harmonic coefficients of GRACE level-2 data from CSR-RL04 and produced a smoothed EWH map. Empirical Orthogonal Functions(EOF)/Principal Component Analysis(PCA) have been introduced as well, in order to extract the melting information associated with the recent warming climate. Next, the Greenland area is redefined by 16 basins and the corresponding melting zones are quantified respectively. Least Squares methods are invoked to interpolate the mass distribution function on each basin. In this way we are able to estimate more accurately regional ice melting rate and we sharpen the EWH map. After comparing our results with a hydrological model the combination SMB - D is established which contains the surface mass balance (SMB) and ice-discharge (D). A general agreement can be reached and it turns out this method is capable to enhance our understanding of the shrinking global cryosphere

Modelling the contribution of supraglacial ice cliffs to the mass-balance of glaciers in the Langtang catchment, Nepalese Himalaya

NASA Astrophysics Data System (ADS)

Buri, P.; Steiner, J. F.; Miles, E.; Ragettli, S.; Pellicciotti, F.

2017-12-01

Supraglacial cliffs are typical surface features of debris-covered glaciers worldwide, affecting surface evolution, and mass balance by providing a direct ice-atmosphere interface where melt rates can be very high. As a result, ice cliffs act as windows of energy transfer from the atmosphere to the ice, and enhance melt and mass losses of otherwise insulated ice. However, their contribution to glacier mass balance has never been quantified at the glacier scale, and all inference has been obtained from upscaling results of point-scale models or observations at select individual cliffs. Here we use a 3D, physically-based backwasting model to estimate the volume losses associated with the melting and backwasting of supraglacial ice cliffs for the entire debris-covered glacier area of the Langtang catchment. We estimate mass losses for the 2014 melt season and compare them to recent values of glacier mass balance determined from geodetic and numerical modelling approached. Cliff outlines and topography are derived from high-resolution stereo SPOT6-imagery from April 2014. Meteorological data to force the model are provided by automatic weather stations on- and off-glacier within the valley. The model simulates ice cliff backwasting by considering the cliff-atmosphere energy-balance, reburial by debris and the effects of adjacent ponds. In the melt season of 2014, cliffs' distribution and patterns of mass losses vary considerably from glacier to glacier, and we relate rates of volume loss to both glaciers' and cliffs' characteristics. Only cliffs with a northerly aspect account for substantial losses. Uncertainty in our estimates is due to the quality of the stereo DEM, uncertainties in the cliff delineation and the fact that we use a conservative approach to cliff delineation and discard very small cliffs and those for which uncertainty in topography is high. Despite these uncertainties, our work presents the first estimate of the importance of supraglacial ice-cliffs to total glacier mass-balance, and shows that the volume lost by backwasting of ice cliffs is a non-negligible term in the total glacier mass balance of debris-covered glaciers, providing a partial explanation of the higher-than-expected mass losses of debris-covered glaciers of High Mountain Asia.

Estimation of terpene content in loblolly pine biomass using a hybrid fast-GC and pyrolysis-molecular beam mass spectrometry method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harman-Ware, Anne E.; Davis, Mark F.; Peter, Gary F.

Terpenes can be used as renewable fuels and chemicals and quantifying their presence in biomass is becoming increasingly important. A novel method was developed to rapidly quantify total diterpenoid resin acids using pyrolysis-molecular beam mass spectrometry (py-MBMS). Pine sapling monoterpenes and diterpenoids were extracted from wood using a 1:1 (v/v) mixture of hexane and acetone and analyses were performed before and after extraction to determine the extraction efficiency of the solvent system. The resulting extract was analyzed for total diterpenoid content using py-MBMS and was combined with total monoterpene content that was determined using a low thermal mass modular acceleratedmore » column heater (LTM MACH) fast-GC/FID to measure the terpene content present in pine saplings. Oleoresin extruded from larger pine trees was used to validate mass balance closure of the terpene content in the extract solvent.« less

Estimation of terpene content in loblolly pine biomass using a hybrid fast-GC and pyrolysis-molecular beam mass spectrometry method

DOE PAGES

Harman-Ware, Anne E.; Davis, Mark F.; Peter, Gary F.; ...

2017-01-16

Terpenes can be used as renewable fuels and chemicals and quantifying their presence in biomass is becoming increasingly important. A novel method was developed to rapidly quantify total diterpenoid resin acids using pyrolysis-molecular beam mass spectrometry (py-MBMS). Pine sapling monoterpenes and diterpenoids were extracted from wood using a 1:1 (v/v) mixture of hexane and acetone and analyses were performed before and after extraction to determine the extraction efficiency of the solvent system. The resulting extract was analyzed for total diterpenoid content using py-MBMS and was combined with total monoterpene content that was determined using a low thermal mass modular acceleratedmore » column heater (LTM MACH) fast-GC/FID to measure the terpene content present in pine saplings. Oleoresin extruded from larger pine trees was used to validate mass balance closure of the terpene content in the extract solvent.« less

High-resolution DEMs for High-mountain Asia: A systematic, region-wide assessment of geodetic glacier mass balance and dynamics

NASA Astrophysics Data System (ADS)

Shean, D. E.; Arendt, A. A.; Osmanoglu, B.; Montesano, P.

2017-12-01

High Mountain Asia (HMA) constitutes the largest glacierized region outside of the Earth's polar regions. Although available observations are limited, long-term records indicate sustained regional glacier mass loss since 1850, with increased loss in recent decades. Recent satellite data (e.g., GRACE, ICESat-1) show spatially variable glacier mass balance, with significant mass loss in the Himalaya and Hindu Kush and slight mass gain in the Karakoram. We generated 4000 high-resolution digital elevation models (DEMs) from sub-meter commercial stereo imagery (DigitalGlobe WorldView/GeoEye) acquired over glaciers in High-mountain Asia from 2002-present (mostly 2013-present). We produced a regional 8-m DEM mosaic for 2015 and estimated 15-year geodetic mass balance for 40000 glaciers larger than 0.1 km2. We are combining with other regional DEM sources to systematically document the spatiotemporal evolution of glacier mass balance for the entire HMA region. We also generated monthly to interannual DEM and velocity time series for high-priority sites distributed across the region, with >15-20 DEMs available for some locations from 2010-present. These records document glacier dynamics, seasonal snow accumulation/redistribution, and processes that affect glacier mass balance (e.g., ice-cliff retreat, debris cover evolution). These efforts will provide basin-scale assessments of snow/ice melt runoff contributions for model cal/val and downstream water resources applications. We will continue processing all archived and newly available commercial stereo imagery for HMA, and will release all DEMs through the HiMAT DAAC.

Simulations of Fractal Star Cluster Formation. I. New Insights for Measuring Mass Segregation of Star Clusters with Substructure

NASA Astrophysics Data System (ADS)

Yu, Jincheng; Puzia, Thomas H.; Lin, Congping; Zhang, Yiwei

2017-05-01

We compare the existent methods, including the minimum spanning tree based method and the local stellar density based method, in measuring mass segregation of star clusters. We find that the minimum spanning tree method reflects more the compactness, which represents the global spatial distribution of massive stars, while the local stellar density method reflects more the crowdedness, which provides the local gravitational potential information. It is suggested to measure the local and the global mass segregation simultaneously. We also develop a hybrid method that takes both aspects into account. This hybrid method balances the local and the global mass segregation in the sense that the predominant one is either caused by dynamical evolution or purely accidental, especially when such information is unknown a priori. In addition, we test our prescriptions with numerical models and show the impact of binaries in estimating the mass segregation value. As an application, we use these methods on the Orion Nebula Cluster (ONC) observations and the Taurus cluster. We find that the ONC is significantly mass segregated down to the 20th most massive stars. In contrast, the massive stars of the Taurus cluster are sparsely distributed in many different subclusters, showing a low degree of compactness. The massive stars of Taurus are also found to be distributed in the high-density region of the subclusters, showing significant mass segregation at subcluster scales. Meanwhile, we also apply these methods to discuss the possible mechanisms of the dynamical evolution of the simulated substructured star clusters.

Simulations of Fractal Star Cluster Formation. I. New Insights for Measuring Mass Segregation of Star Clusters with Substructure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Jincheng; Puzia, Thomas H.; Lin, Congping

2017-05-10

We compare the existent methods, including the minimum spanning tree based method and the local stellar density based method, in measuring mass segregation of star clusters. We find that the minimum spanning tree method reflects more the compactness, which represents the global spatial distribution of massive stars, while the local stellar density method reflects more the crowdedness, which provides the local gravitational potential information. It is suggested to measure the local and the global mass segregation simultaneously. We also develop a hybrid method that takes both aspects into account. This hybrid method balances the local and the global mass segregationmore » in the sense that the predominant one is either caused by dynamical evolution or purely accidental, especially when such information is unknown a priori. In addition, we test our prescriptions with numerical models and show the impact of binaries in estimating the mass segregation value. As an application, we use these methods on the Orion Nebula Cluster (ONC) observations and the Taurus cluster. We find that the ONC is significantly mass segregated down to the 20th most massive stars. In contrast, the massive stars of the Taurus cluster are sparsely distributed in many different subclusters, showing a low degree of compactness. The massive stars of Taurus are also found to be distributed in the high-density region of the subclusters, showing significant mass segregation at subcluster scales. Meanwhile, we also apply these methods to discuss the possible mechanisms of the dynamical evolution of the simulated substructured star clusters.« less

Studying the Effects of Amazonian Land Cover Change on Glacier Mass Balance in the Tropical Andes

NASA Astrophysics Data System (ADS)

Mark, B. G.; Fernandez, A.; Gabrielli, P.; Montenegro, A.; Postigo, J.; Hellstrom, R. A.

2017-12-01

Recent research has highlighted several ongoing environmental changes occurring across Tropical South America, including Andean glacier retreat, drought, as well as changes in land-use and land-cover. As the regional climate of the area is mostly characterized by land-ocean interactions, the atmospheric convection in the Amazon, and the effect of the Andes on circulation patterns, it follows that changes in one of those regions may affect the other. Most scholars who have studied the causes of tropical glaciers' fluctuations have not analyzed the linkages with changes in the Amazon with the same attention paid to the influence of Pacific sea surface temperature. Here we study the response of glacier surface mass balance in the Cordillera Blanca, Peru (10°S), to a scenario where the Amazonian rainforest is replaced by savannas. We ran climatic simulations at 2-km spatial resolution utilizing the Weather Research and Forecasting (WRF) model considering two scenarios: (a) control (CRTL), with today's rainforest extent; and (b) land cover change (LCC), where all the rainforest was replaced by savanna. WRF output was in turn ingested into a glacier energy and mass balance (GEMB) model that we validate by reconstructing both the accumulated mass balance from available observations, and the altitudinal distribution of mass balance in the region. Seasonal comparison between CRTL and LCC scenarios indicates that forest replacement by savanna results in more positive glacier mass balance. This shift to more positive mass balance contrasts with a (WRF) modeled rise in the elevation of the freezing line (0°C) between 30 to 120 m for the LCC scenario. Our results are surprising because most previous studies have shown that reducing Amazon forest cover diminishes rainfall and increases temperature, suggesting that glaciers should lose mass. We hypothesize and discuss implications of possible land-atmospheric processes that might drive this tropical glacier response to Amazonian forest change, including: the large-scale influence of Amazonian albedo change on the interaction between the Walker and Hadley cells and the effect of mountain meteorology dynamics.

Formation of nonextractable soil residues: A stable isotope approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Richnow, H.H.; Eschenback, A.; Mahro, B.

1999-11-01

Stable carbon isotopic measurements were employed to characterize the transformation of a {sup 13}C-labeled polycyclic aromatic hydrocarbon (PAH), anthracene, in a closed soil bioreactor system. The {sup 13}C-label was used to calculate a carbon mass balance including mineralization and the formation of nonextractable soil-bound residues. Similar results were obtained from {sup 13}C-labeled carbon and {sup 14}C-labeled carbon mass balance calculations for separate batch experiments with labeled anthracene. In concentration ranges typical for real PAH-contaminated sites, the sensitivity of the {sup 13}C tracer method meets the requirements of classical radiotracer experiments. Therefore, the authors balancing method based on stable isotope-labeled chemicalsmore » may supplement or substitute radiotracer experiments under many circumstances. One major advantage of using stable isotope-labeled tracers is the possible application in transformation studies where the use of radioactive substances is of environmental concern. The transformation of {sup 13}C-labeled PAH into nonextractable residues clearly depends on the metabolic activity of the soil microflora and occurs during an early phase of biodegradation. Successive contamination of the soil by anthracene leads to a progressive adaptation of the microflora to a complete mineralization of anthracene in the soil. The extent of residue formation is controlled by the capability of the microflora to degrade the contaminant. Results of long-term experiments indicate that nonextractable residues are relatively stable over time.« less

40 CFR 98.244 - Monitoring and QA/QC requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... procedures specified in § 98.34(c). (b) If you use the mass balance methodology in § 98.243(c), use the... of Carbon, Hydrogen, and Nitrogen in Petroleum Products and Lubricants (incorporated by reference..., Hydrogen, and Nitrogen in Laboratory Samples of Coal (incorporated by reference, see § 98.7). (viii) Method...

40 CFR 98.244 - Monitoring and QA/QC requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... procedures specified in § 98.34(c). (b) If you use the mass balance methodology in § 98.243(c), use the... of Carbon, Hydrogen, and Nitrogen in Petroleum Products and Lubricants (incorporated by reference..., Hydrogen, and Nitrogen in Laboratory Samples of Coal (incorporated by reference, see § 98.7). (viii) Method...

40 CFR 98.244 - Monitoring and QA/QC requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... procedures specified in § 98.34(c). (b) If you use the mass balance methodology in § 98.243(c), use the... of Carbon, Hydrogen, and Nitrogen in Petroleum Products and Lubricants (incorporated by reference..., Hydrogen, and Nitrogen in Laboratory Samples of Coal (incorporated by reference, see § 98.7). (viii) Method...

40 CFR Table 2 of Subpart Bbbbbbb... - Initial Compliance Demonstration Methods With the Emission Reduction and PM Concentration...

Code of Federal Regulations, 2011 CFR

2011-07-01

... Emission Standards for Hazardous Air Pollutants for Area Sources: Chemical Preparations Industry Other... less; or c. Provide engineering calculations, such as mass balance and flow rate calculations, that demonstrate that the control device is capable of reducing PM concentration from the chemical preparations...

40 CFR Table 2 of Subpart Bbbbbbb... - Initial Compliance Demonstration Methods With the Emission Reduction and PM Concentration...

Code of Federal Regulations, 2010 CFR

2010-07-01

... Emission Standards for Hazardous Air Pollutants for Area Sources: Chemical Preparations Industry Other... less; or c. Provide engineering calculations, such as mass balance and flow rate calculations, that demonstrate that the control device is capable of reducing PM concentration from the chemical preparations...

40 CFR Table 2 of Subpart Bbbbbbb... - Initial Compliance Demonstration Methods With the Emission Reduction and PM Concentration...

Code of Federal Regulations, 2012 CFR

2012-07-01

... Emission Standards for Hazardous Air Pollutants for Area Sources: Chemical Preparations Industry Other... less; or c. Provide engineering calculations, such as mass balance and flow rate calculations, that demonstrate that the control device is capable of reducing PM concentration from the chemical preparations...

40 CFR Table 2 of Subpart Bbbbbbb... - Initial Compliance Demonstration Methods With the Emission Reduction and PM Concentration...

Code of Federal Regulations, 2014 CFR

2014-07-01

... Emission Standards for Hazardous Air Pollutants for Area Sources: Chemical Preparations Industry Other... less; or c. Provide engineering calculations, such as mass balance and flow rate calculations, that demonstrate that the control device is capable of reducing PM concentration from the chemical preparations...

40 CFR Table 2 of Subpart Bbbbbbb... - Initial Compliance Demonstration Methods With the Emission Reduction and PM Concentration...

Code of Federal Regulations, 2013 CFR

2013-07-01

... Emission Standards for Hazardous Air Pollutants for Area Sources: Chemical Preparations Industry Other... less; or c. Provide engineering calculations, such as mass balance and flow rate calculations, that demonstrate that the control device is capable of reducing PM concentration from the chemical preparations...

BUILDING FEATURES THAT INFLUENCE THE PENETRATION OF TOXIC GASES FROM THE AMBIENT TO THE INDOOR ENVIRONMENT

EPA Science Inventory

Strategies to reduce indoor exposures to certain toxic air contaminants suggested a study of the penetration of these toxics from the external atmosphere into an unoccupied research house. The mass balance method is applied to measure rates of sorption and re-emission of the con...

Airborne remote sensing and in situ measurements of atmospheric CO2 to quantify point source emissions

NASA Astrophysics Data System (ADS)

Krings, Thomas; Neininger, Bruno; Gerilowski, Konstantin; Krautwurst, Sven; Buchwitz, Michael; Burrows, John P.; Lindemann, Carsten; Ruhtz, Thomas; Schüttemeyer, Dirk; Bovensmann, Heinrich

2018-02-01

Reliable techniques to infer greenhouse gas emission rates from localised sources require accurate measurement and inversion approaches. In this study airborne remote sensing observations of CO2 by the MAMAP instrument and airborne in situ measurements are used to infer emission estimates of carbon dioxide released from a cluster of coal-fired power plants. The study area is complex due to sources being located in close proximity and overlapping associated carbon dioxide plumes. For the analysis of in situ data, a mass balance approach is described and applied, whereas for the remote sensing observations an inverse Gaussian plume model is used in addition to a mass balance technique. A comparison between methods shows that results for all methods agree within 10 % or better with uncertainties of 10 to 30 % for cases in which in situ measurements were made for the complete vertical plume extent. The computed emissions for individual power plants are in agreement with results derived from emission factors and energy production data for the time of the overflight.

Establishment of the purity values of carbohydrate certified reference materials using quantitative nuclear magnetic resonance and mass balance approach.

PubMed

Quan, Can

2014-06-15

This work described the assignment of purity values to six carbohydrate certified reference materials, including glucose, fructose, galactose, lactose, xylose and sucrose, according to the ISO Guides 34 and 35. The CRMs' purity values were assigned based on the weighted average of quantitative nuclear magnetic resonance method and mass balance approach with high resolution liquid chromatography - evaporative light scattering detection. All the six CRMs with following value amount fractions: glucose (GBW10062) at a certified purity P ± U (k=2) of (0.99 ± 0.005)%; fructose (GBW10063) at (0.99 ± 0.005)%; galactose (GBW10064) at (0.99 ± 0.007)%; lactose (GBW10065) at (0.99 ± 0.008)%; xylose (GBW10066) at (0.99 ± 0.007)% and sucrose (GBW10067) at (0.99 ± 0.008)%, respectively were certified. The homogeneity of the CRMs was determined by an in-house validated liquid chromatographic method. Potential degradation during storage was also investigated and a shelf-life based on this value was established. Copyright © 2013 Elsevier Ltd. All rights reserved.

Estimates of Ground-Water Recharge in Wadis of Arid, Mountainous Areas Using the Chloride Mass-Balance Approach

NASA Astrophysics Data System (ADS)

Wood, W. W.; Wood, W. W.

2001-05-01

Evaluation of ground-water supply in arid areas requires estimation of annual recharge. Traditional physical-based hydrologic estimates of ground-water recharge result in large uncertainties when applied in arid, mountainous environments because of infrequent, intense rainfall events, destruction of water-measuring structures associated with those events, and consequent short periods of hydrologic records. To avoid these problems and reduce the uncertainty of recharge estimates, a chloride mass-balance (CMB) approach was used to provide a time-integrated estimate. Seven basins exhibiting dry-stream beds (wadis) in the Asir and Hijaz Mountains, western Saudi Arabia, were selected to evaluate the method. Precipitation among the basins ranged from less than 70 mm/y to nearly 320 mm/y. Rain collected from 35 locations in these basins averaged 2.0 mg/L chloride. Ground water from 140 locations in the wadi alluvium averaged 200 mg/L chloride. This chloride concentration ratio of precipitation to ground water suggests that on average, approximately 1 percent of the rainfall is recharged, while the remainder is lost to evaporation. Ground-water recharge from precipitation in individual basins ranged from less than 1 to nearly 4 percent and was directly proportional to total precipitation. Independent calculations of recharge using Darcy's Law were consistent with these findings and are within the range typically found in other arid areas of the world. Development of ground water has lowered the water level beneath the wadis and provided more storage thus minimizing chloride loss from the basin by river discharge. Any loss of chloride from the basin results in an overestimate of the recharge flux by the chloride-mass balance approach. In well-constrained systems recharge in arid, mountainous areas where the mass of chloride entering and leaving the basin is known or can be reasonably estimated, the CMB approach provides a rapid, inexpensive method for estimating time-integrated ground-water recharge.

Mass, heat and freshwater fluxes in the South Indian Ocean

NASA Technical Reports Server (NTRS)

Fu, Lee-Lueng

1986-01-01

Six hydrographic sections were used to examine the circulation and property fluxes in the South Indian Ocean from 10 to 32 deg S. The calculations were made by applying an inverse method to the data. In the interior of the South Indian Ocean, the geostrophic flow is generally northward. At 18 deg S, the northward interior mass flux is balanced by the southward Ekman mass flux at the surface, whereas at 32 deg S the northward interior mass flux is balanced by the southward mass flux of the Agulhas Current. There is a weak, southward mass flux of 6 x 10 to the 9th kg/s in the Mozambique Channel. The rate of water exchange between the Pacific Ocean and the Indian Ocean is dependent on the choice of the initial reference level used in the inverse calculation. The choice of 1500 m, the depth of the deep oxygen minimum, has led to a flux of water from the Pacific Ocean to the Indian Ocean at a rate of 6.6 x 10 to the 9th kg/s. Heat flux calculations indicate that the Indian Ocean is exporting heat to the rest of the world's oceans at a rate of -0.69 x 10 to the 15th W at 18 deg S and -0.25 x 10 to the 15th W at 32 deg S (negative values being southward).

Mercury Emission Measurement at a CFB Plant

DOE Office of Scientific and Technical Information (OSTI.GOV)

John Pavlish; Jeffrey Thompson; Lucinda Hamre

2009-02-28

In response to pending regulation to control mercury emissions in the United States and Canada, several projects have been conducted to perform accurate mass balances at pulverized coal (pc)-fired utilities. Part of the mercury mass balance always includes total gaseous mercury as well as a determination of the speciation of the mercury emissions and a concentration bound to the particulate matter. This information then becomes useful in applying mercury control strategies, since the elemental mercury has traditionally been difficult to control by most technologies. In this instance, oxidation technologies have proven most beneficial for increased capture. Despite many years ofmore » mercury measurement and control projects at pc-fired units, far less work has been done on circulating fluidized-bed (CFB) units, which are able to combust a variety of feedstocks, including cofiring coal with biomass. Indeed, these units have proven to be more problematic because it is very difficult to obtain a reliable mercury mass balance. These units tend to have very different temperature profiles than pc-fired utility boilers. The flexibility of CFB units also tends to be an issue when a mercury balance is determined, since the mercury inputs to the system come from the bed material and a variety of fuels, which can have quite variable chemistry, especially for mercury. In addition, as an integral part of the CFB operation, the system employs a feedback loop to circulate the bed material through the combustor and the solids collection system (the primary cyclone), thereby subjecting particulate-bound metals to higher temperatures again. Despite these issues, CFB boilers generally emit very little mercury and show good native capture. The Energy & Environmental Research Center is carrying out this project for Metso Power in order to characterize the fate of mercury across the unit at Rosebud Plant, an industrial user of CFB technology from Metso. Appropriate solids were collected, and flue gas samples were obtained using the Ontario Hydro method, mercury continuous emission monitors, and sorbent trap methods. In addition, chlorine and fluorine were determined for solids and in the flue gas stream. Results of this project have indicated a very good mercury mass balance for Rosebud Plant, indicating 105 {+-} 19%, which is well within acceptable limits. The mercury flow through the system was shown to be primarily in with the coal and out with the flue gas, which falls outside of the norm for CFB boilers.« less

Wii balance board exercise improves balance and lower limb muscle strength of overweight young adults.

PubMed

Siriphorn, Akkradate; Chamonchant, Dannaovarat

2015-01-01

[Purpose] The potential health benefits of the Nintendo Wii balance board exercise have been widely investigated. However, no study has been conducted to examine the benefits of Wii exercise for overweight young adults. The aim of this study was to investigate the effect of exercise performed on a Nintendo Wii balance board on the balance and lower limb muscle strength in overweight young adults. [Subjects and Methods] Within-subject repeated measures analysis was used. Sixteen young adults (aged 21.87±1.13 years, body mass index 24.15 ± 0.50 kg/m(2)) were recruited. All subjects performed an exercise program on a Wii balance board for 8 weeks (30 min/session, twice a week for 8 weeks). A NeuroCom Balance Master and a hand-held dynamometer were used to measure balance performance and lower limb muscle strength. [Results] According to the comparison of pre- and post-intervention measurements, the Wii balance board exercise program significantly improved the limit of stability parameters. There was also a significant increase in strength of four lower-limb muscle groups: the hip flexor, knee flexor, ankle dorsiflexor and ankle plantarflexor. [Conclusion] These findings suggest that a Wii balance board exercise program can be used to improve the balance and lower limb muscle strength of overweight young adults.

Supplementing an energy adequate, higher protein diet with protein does not enhance fat-free mass restoration after short-term severe negative energy balance.

PubMed

Berryman, C E; Sepowitz, J J; McClung, H L; Lieberman, H R; Farina, E K; McClung, J P; Ferrando, A A; Pasiakos, S M

2017-06-01

Negative energy balance during military operations can be severe and result in significant reductions in fat-free mass (FFM). Consuming supplemental high-quality protein following such military operations may accelerate restoration of FFM. Body composition (dual-energy X-ray absorptiometry) and whole body protein turnover (single-pool [ 15 N]alanine method) were determined before (PRE) and after 7 days (POST) of severe negative energy balance during military training in 63 male US Marines (means ± SD, 25 ± 3 yr, 84 ± 9 kg). After POST measures were collected, volunteers were randomized to receive higher protein (HIGH: 1,103 kcal/day, 133 g protein/day), moderate protein (MOD: 974 kcal/day, 84 g protein/day), or carbohydrate-based low protein control (CON: 1,042 kcal/day, 7 g protein/day) supplements, in addition to a self-selected, ad libitum diet, for the 27-day intervention (REFED). Measurements were repeated POST-REFED. POST total body mass (TBM; -5.8 ± 1.0 kg, -7.0%), FFM (-3.1 ± 1.6 kg, -4.7%), and net protein balance (-1.7 ± 1.1 g protein·kg -1 ·day -1 ) were lower and proteolysis (1.1 ± 1.9 g protein·kg -1 ·day -1 ) was higher compared with PRE ( P < 0.05). Self-selected, ad libitum dietary intake during REFED was similar between groups (3,507 ± 730 kcal/day, 2.0 ± 0.5 g protein·kg -1 ·day -1 ). However, diets differed by protein intake due to supplementation (CON: 2.0 ± 0.4, MOD: 3.2 ± 0.7, and HIGH: 3.5 ± 0.7 g·kg -1 ·day -1 ; P < 0.05) but not total energy (4,498 ± 725 kcal/day). All volunteers, independent of group assignment, achieved positive net protein balance (0.4 ± 1.0 g protein·kg -1 ·day -1 ) and gained TBM (5.9 ± 1.7 kg, 7.8%) and FFM (3.6 ± 1.8 kg, 5.7%) POST-REFED compared with POST ( P < 0.05). Supplementing ad libitum, energy-adequate, higher protein diets with additional protein may not be necessary to restore FFM after short-term severe negative energy balance. NEW & NOTEWORTHY This article demonstrates 1 ) the majority of physiological decrements incurred during military training (e.g., total and fat-free mass loss), with the exception of net protein balance, resolve and return to pretraining values after 27 days and 2 ) protein supplementation, in addition to an ad libitum, higher protein (~2.0 g·kg -1 ·day -1 ), energy adequate diet, is not necessary to restore fat-free mass following short-term severe negative energy balance.

A comparative study of energy balance among housewives of Ludhiana city.

PubMed

Kaur, N; Mann, S K; Sidhu, P; Sangha, J K

1997-01-01

Energy gap is the main nutritional factor which affects work efficiency in all age groups. The low intake of food results in impaired working efficiency and a low level of vitality. Energy balance was evaluated among 30 healthy, nonpregnant, nonlactating housewives aged 29-40 years drawn from the campus of Punjab Agricultural University and its surrounding areas. The women's mean overall energy intake was 1777 +or- 31 kcal/day, 87% of the ICMR (1990) recommended allowances. Total energy expenditure was measured using a computer-based Nutriguide program of Song et al., Caltrac, FAO/WHO/UNU (1985) equations based upon body weight, and an ICMR (1990) prediction equation also based upon body weight. Statistical analysis identified a significant difference in the energy expenditure measured by all 4 methods except between the FAO/WHO/UNU and ICMR prediction equations. The overall energy balance was maximum and positive according to Caltrac at 4.5 kcal/day. The energy expenditure measured by the Nutriguide, FAO/WHO/UNU, and ICMR methods was significantly correlated to weight. Energy intake was significantly and highly correlated to energy balance in all of the 4 methods. While the subjects were overweight when compared with Life Insurance Corporation of India (1965) Standards, the women's body mass index of 23.11 kg/sq.m was within the normal range.

Stochastic weighted particle methods for population balance equations with coagulation, fragmentation and spatial inhomogeneity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Kok Foong; Patterson, Robert I.A.; Wagner, Wolfgang

2015-12-15

Graphical abstract: -- Highlights: •Problems concerning multi-compartment population balance equations are studied. •A class of fragmentation weight transfer functions is presented. •Three stochastic weighted algorithms are compared against the direct simulation algorithm. •The numerical errors of the stochastic solutions are assessed as a function of fragmentation rate. •The algorithms are applied to a multi-dimensional granulation model. -- Abstract: This paper introduces stochastic weighted particle algorithms for the solution of multi-compartment population balance equations. In particular, it presents a class of fragmentation weight transfer functions which are constructed such that the number of computational particles stays constant during fragmentation events. Themore » weight transfer functions are constructed based on systems of weighted computational particles and each of it leads to a stochastic particle algorithm for the numerical treatment of population balance equations. Besides fragmentation, the algorithms also consider physical processes such as coagulation and the exchange of mass with the surroundings. The numerical properties of the algorithms are compared to the direct simulation algorithm and an existing method for the fragmentation of weighted particles. It is found that the new algorithms show better numerical performance over the two existing methods especially for systems with significant amount of large particles and high fragmentation rates.« less

Mass Property Measurements of the Mars Science Laboratory Rover

NASA Technical Reports Server (NTRS)

Fields, Keith

2012-01-01

The NASA/JPL Mars Science Laboratory (MSL) spacecraft mass properties were measured on a spin balance table prior to launch. This paper discusses the requirements and issues encountered with the setup, qualification, and testing using the spin balance table, and the idiosyncrasies encountered with the test system. The final mass measurements were made in the Payload Hazardous Servicing Facility (PHSF) at Kennedy Space Center on the fully assembled and fueled spacecraft. This set of environmental tests required that the control system for the spin balance machine be at a remote location, which posed additional challenges to the operation of the machine

The Martian climate: Energy balance models with CO2/H2O atmospheres

NASA Technical Reports Server (NTRS)

Hoffert, M. I.

1985-01-01

Coupled equations are developed for mass and heat transport in a seasonal Mars model with condensation and sublimation of CO2 at the polar caps. Topics covered include physical considerations of planetary as mass and energy balance; effects of phase changes at the surface on mass and heat flux; atmospheric transport and governing equations; and numerical analysis.

Long-term variability in sugarcane bagasse feedstock compositional methods: Sources and magnitude of analytical variability

DOE PAGES

Templeton, David W.; Sluiter, Justin B.; Sluiter, Amie; ...

2016-10-18

In an effort to find economical, carbon-neutral transportation fuels, biomass feedstock compositional analysis methods are used to monitor, compare, and improve biofuel conversion processes. These methods are empirical, and the analytical variability seen in the feedstock compositional data propagates into variability in the conversion yields, component balances, mass balances, and ultimately the minimum ethanol selling price (MESP). We report the average composition and standard deviations of 119 individually extracted National Institute of Standards and Technology (NIST) bagasse [Reference Material (RM) 8491] run by seven analysts over 7 years. Two additional datasets, using bulk-extracted bagasse (containing 58 and 291 replicates each),more » were examined to separate out the effects of batch, analyst, sugar recovery standard calculation method, and extractions from the total analytical variability seen in the individually extracted dataset. We believe this is the world's largest NIST bagasse compositional analysis dataset and it provides unique insight into the long-term analytical variability. Understanding the long-term variability of the feedstock analysis will help determine the minimum difference that can be detected in yield, mass balance, and efficiency calculations. The long-term data show consistent bagasse component values through time and by different analysts. This suggests that the standard compositional analysis methods were performed consistently and that the bagasse RM itself remained unchanged during this time period. The long-term variability seen here is generally higher than short-term variabilities. It is worth noting that the effect of short-term or long-term feedstock compositional variability on MESP is small, about $0.03 per gallon. The long-term analysis variabilities reported here are plausible minimum values for these methods, though not necessarily average or expected variabilities. We must emphasize the importance of training and good analytical procedures needed to generate this data. As a result, when combined with a robust QA/QC oversight protocol, these empirical methods can be relied upon to generate high-quality data over a long period of time.« less

Long-term variability in sugarcane bagasse feedstock compositional methods: Sources and magnitude of analytical variability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Templeton, David W.; Sluiter, Justin B.; Sluiter, Amie

In an effort to find economical, carbon-neutral transportation fuels, biomass feedstock compositional analysis methods are used to monitor, compare, and improve biofuel conversion processes. These methods are empirical, and the analytical variability seen in the feedstock compositional data propagates into variability in the conversion yields, component balances, mass balances, and ultimately the minimum ethanol selling price (MESP). We report the average composition and standard deviations of 119 individually extracted National Institute of Standards and Technology (NIST) bagasse [Reference Material (RM) 8491] run by seven analysts over 7 years. Two additional datasets, using bulk-extracted bagasse (containing 58 and 291 replicates each),more » were examined to separate out the effects of batch, analyst, sugar recovery standard calculation method, and extractions from the total analytical variability seen in the individually extracted dataset. We believe this is the world's largest NIST bagasse compositional analysis dataset and it provides unique insight into the long-term analytical variability. Understanding the long-term variability of the feedstock analysis will help determine the minimum difference that can be detected in yield, mass balance, and efficiency calculations. The long-term data show consistent bagasse component values through time and by different analysts. This suggests that the standard compositional analysis methods were performed consistently and that the bagasse RM itself remained unchanged during this time period. The long-term variability seen here is generally higher than short-term variabilities. It is worth noting that the effect of short-term or long-term feedstock compositional variability on MESP is small, about $0.03 per gallon. The long-term analysis variabilities reported here are plausible minimum values for these methods, though not necessarily average or expected variabilities. We must emphasize the importance of training and good analytical procedures needed to generate this data. As a result, when combined with a robust QA/QC oversight protocol, these empirical methods can be relied upon to generate high-quality data over a long period of time.« less

The Inside Scoop: Intermodel comparison of englacial layers in the central West Antarctic Ice Sheet and how simulations compare to the real deal

NASA Astrophysics Data System (ADS)

Muldoon, G.; Jackson, C. S.; Young, D. A.; Blankenship, D. D.

2016-12-01

Understanding mass balance and volumetric change of glaciers are extremely important in areas where the majority of the population depends on cryospheric sources for the livelihood. Ladakh is one of the coldest and the aridest region of India. The majority of the population live in mountain pockets where the only source of water is snow and glacier melt for agriculture and domestic use. Stok village catchment (52 km2) has seven very small glaciers with an area ranging between 0.2-1.05 km2 at an elevation above 5300m a.s.l (GSI 2009). These glaciers contribute to a stream feeding Stok village of 274 ( 1469 individuals) households and a portion of Chuchot village before joining the Indus River. Ironically very limited studies have been carried out so far in this region, making it even more urgent to monitor the health of the glaciers in this region. With the changing climate, booming of the tourism industry and scarcity of water resources during the spring season, there is a shift in the livelihood of the region towards other option leading to a negative impact on the environment and over exploitation of natural resources. In this study we present analysis of measured annual mass balances for the period 2015-2017 and reconstruction of annual mass balances since 1969 to 2015 of Stok glacier located on the north eastern slope of Zanskar range in Ladakh region of western Himalayas. Direct glaciological methods were used to obtain annual mass balance for 2015-2017 and for reconstruction of annual mass balances, Classical Temperature Index model were used with the help of meteorological data from Indian Meteorological Department. The data gaps were filled with the help of several modelled datasets viz. HAR (High Asia Reanalysis), REMO, and Climate Research Unit (CRU) TS2.1 dataset. We also present catchment wide change in volume of the glaciers since 1969 to 2015. Declassified satellite images and Landsat images were used to obtain the change in volume of the glacier with the help of already established empirical relationships. Since the region has a large number of such catchments (mountain pockets) therefore understanding one such catchment (e.g. Stok village catchment) will surely help policy making on a larger scale. Acknowledgement: Authors thank UGC UPOE II (project) for the support

Impact of monsoonal rainfall on specific mass balance in ablation zone of Chhota Shigri Glacier in 2008, Himachal Pradesh, India

NASA Astrophysics Data System (ADS)

Sharma, P.; Ramanathan, A.; Linda, A.; Wagnon, P.; Arnod, Y.; Jose, P. G.; Chevallier, P.

2009-04-01

The Mass Balance of the Chhota Shigri glacier (32.2°N, 77.5°E; 15.7 km2, 4050 to 6263m a.m.s.l., 9 km long) located in Lahaul and Spiti valley, Himachal Pradesh, India has been monitored from 2002 to 2008 using glaciological method. In 2008, an additional field survey during 3- 10th August was undertaken to understand the impact of monsoonal rainfall on specific mass balance at various points on the ablation zone of this glacier that is alternatively influenced by the Indian monsoon and the mid-latitude westerlies. Specific Annual Mass Balance is negative (0.93 mweq), Equilibrium Line Altitude (ELA) is 5120m and Accumulation Area Ratio (AAR) is 38% in the 2007-08 hydrological year. In 2008 data obtained from nearest Weather station at Keylong show that the monsoon hit the Spiti valley in the middle of June (15 days earlier than normal date ) .The results reveal that 70% of total specific mass balance occurred by the first week of August indicating that most of the melting occurred in the first half of ablation season, dominated by monsoonal rainfall. The rainfall may accelerate ablation rate by supplying ( heat ) energy even it is very low and exposing bare dirty ice thereby decreasing albedo. In part A of the glacier, the mean vertical gradient of ablation up to August 08 is 0.67 m w.e. 100 m-1 between 4350 and 4850 m a.s.l., (area free of debris) and for part B, it is 0.41 m w.e. 100 m-1 between 4600m a.s.l. and 5000m a.s.l. From August 08 up to 1st week of October, mean vertical gradient of the ablation for part A is 0.54m w.e. 100 m-1 and it is 0.61 m w.e. 100 m-1 in part B for the same altitude ranges. Below 4350m a.s.l. the whole glacier is covered by debris and the melting rate is significantly reduced. Overall, ablation rate is influenced by rainfall, incoming solar radiation and debris cover.

Contrasts between chemical and physical estimates of baseflow help discern multiple sources of water contributing to rivers

NASA Astrophysics Data System (ADS)

Cartwright, I.; Gilfedder, B.; Hofmann, H.

2013-05-01

This study compares geochemical and physical methods of estimating baseflow in the upper reaches of the Barwon River, southeast Australia. Estimates of baseflow from physical techniques such as local minima and recursive digital filters are higher than those based on chemical mass balance using continuous electrical conductivity (EC). Between 2001 and 2011 the baseflow flux calculated using chemical mass balance is between 1.8 × 103 and 1.5 × 104 ML yr-1 (15 to 25% of the total discharge in any one year) whereas recursive digital filters yield baseflow fluxes of 3.6 × 103 to 3.8 × 104 ML yr-1 (19 to 52% of discharge) and the local minimum method yields baseflow fluxes of 3.2 × 103 to 2.5 × 104 ML yr-1 (13 to 44% of discharge). These differences most probably reflect how the different techniques characterise baseflow. Physical methods probably aggregate much of the water from delayed sources as baseflow. However, as many delayed transient water stores (such as bank return flow or floodplain storage) are likely to be geochemically similar to surface runoff, chemical mass balance calculations aggregate them with the surface runoff component. The mismatch between geochemical and physical estimates is greatest following periods of high discharge in winter, implying that these transient stores of water feed the river for several weeks to months. Consistent with these interpretations, modelling of bank storage indicates that bank return flows provide water to the river for several weeks after flood events. EC vs. discharge variations during individual flow events also imply that an inflow of low EC water stored within the banks or on the floodplain occurs as discharge falls. The joint use of physical and geochemical techniques allows a better understanding of the different components of water that contribute to river flow, which is important for the management and protection of water resources.

The recycling of heavy-metalcontaining wastes: Mass balances and economical estimations

NASA Astrophysics Data System (ADS)

Antrekowitsch, J.; Steinlechner, S.

2011-01-01

As environmental legislation has become stricter in recent decades, efforts for treating residues have also increased. The existing pyrometallurgical reprocessing methods for metal-containing wastes recover mainly only one valuable metal or produce low-grade byproducts. The aim of developing an economic process has to be the simultaneous recovery of more than one valuable metal and increased product quality. In the case of zinccontaining residues the goal has to be a high-quality zinc product. Moreover, the target is a nearly zero waste process and, accordingly, small amounts of generated residues. In this paper four possible secondary raw materials are compared regarding their mass and energy balance for a treatment in a carbon-containing metal bath. Furthermore, an evaluation of the economy is given for a neutral leaching residue, Waelz kiln slag, dust from secondary copper industry as well as an electro arc furnace dust from carbon steel production.

Evaluation of glacier mass balance by observing variations in transient snowline positions. [Jostedalsbreen ice cap, Norway

NASA Technical Reports Server (NTRS)

Oestrem, G. (Principal Investigator)

1973-01-01

The author has identified the following significant results. The transient snowline on five outlet glaciers from the Jostedalsbreen ice-cap in Southwestern Norway could be determined from ERTS-1 image 1336-10260, when bands MSS 5, 6, and 7 were combined in an additive color viewer. The snowline was situated at a very low altitude at the time of imagery (24 June 1973) indicating that glacier melt was behind normal schedule, a fact that has a hydrologic bearing: one could expect less melt water in the streams. The idea to use ERTS-1 imagery in snowline determinations proved realistic and relatively easy to apply in practice. The method will be useful to estimate the glaciers' mass balance for large areas, provided some ground truth observations are made. Images from the end of the melt season are of course vital in this work.

Evaluation of three methods of different levels of complexity to represent the interactions between the Greenland ice sheet and the atmosphere at the century time scale.

NASA Astrophysics Data System (ADS)

Le clec'h, Sébastien; Fettweis, Xavier; Quiquet, Aurelien; Dumas, Christophe; Kageyama, Masa; Charbit, Sylvie; Ritz, Catherine

2017-04-01

Based on numerous studies showing implications of polar ice sheets on the climate system, the climate community recommended the development of methods to account for feedbacks between polar ice sheets and the other climate components. In this study we used three methods of different levels of complexity to represent the interactions between a Greenland ice sheet model (GRISLI) and a regional atmospheric model (MAR) under the RCP8.5 scenario. The simplest method, i.e. uncoupled, does not account for interactions between both models. In this method MAR computes varying atmospheric conditions using the same present-day observed Greenland ice sheet topography and extent. The outputs are then used to force GRISLI. The second method is a one-way coupling method in which the MAR outputs are corrected to account for topography changes before their transfer to GRISLI. The third method is a fully coupled method allowing the full representation of interactions between MAR and GRISLI. In this case, the ice sheet topography and its extent as seen by the atmospheric model is updated for each ice sheet model time step. The three methods are evaluated regarding the Greenland ice sheet response from 2000 to 2150. As expected, the uncoupled method shows a coastal thinning of the ice sheet due to a decreasing surface mass balance for coastal regions related to increased mean surface temperature. The one-way coupling and the full coupling methods tend to amplify the surface mass balance due to surface elevation feedback. The uncoupled method tends to underestimate the Greenland ice sheet volume reduction compared to both coupling methods over 150 years. This underestimation is of the same order of magnitude of the ice loss from the Greenland peripheral glaciers at the end of the 21st century. As for the uncoupled method, the thinning of the ice sheet occurs in coastal regions for both coupling methods. However compared to the one-way coupling method, the fully coupled method tends to increase the spatial variability of the surface mass balance changes through time. Our results also indicate that differences between the two coupling methods increase with time, which suggests that the choice of the method should depend on the timescale considered. Beyond century scale projections the fully coupled method is necessary in order to avoid underestimation of the ice sheet volume reduction, whilst the one-way method seems to be sufficient to represent the interactions between the atmosphere and the GrIS for projections by the end of the century.

Assessing the impact of dairy waste lagoons on groundwater quality using a spatial analysis of vadose zone and groundwater information in a coastal phreatic aquifer.

PubMed

Baram, S; Kurtzman, D; Ronen, Z; Peeters, A; Dahan, O

2014-01-01

Dairy waste lagoons are considered to be point sources of groundwater contamination by chloride (Cl(-)), different nitrogen-species and pathogens/microorganisms. The objective of this work is to introduce a methodology to assess the past and future impacts of such lagoons on regional groundwater quality. The method is based on a spatial statistical analysis of Cl(-) and total nitrogen (TN) concentration distributions in the saturated and the vadose (unsaturated) zones. The method provides quantitative data on the relation between the locations of dairy lagoons and the spatial variability in Cl(-) and TN concentrations in groundwater. The method was applied to the Beer-Tuvia region, Israel, where intensive dairy farming has been practiced for over 50 years above the local phreatic aquifer. Mass balance calculations accounted for the various groundwater recharge and abstraction sources and sinks in the entire region. The mass balances showed that despite the small surface area covered by the dairy lagoons in this region (0.8%), leachates from lagoons have contributed 6.0% and 12.6% of the total mass of Cl(-) and TN (mainly as NO3(-)-N) added to the aquifer. The chemical composition of the aquifer and vadose zone water suggested that irrigated agricultural activity in the region is the main contributor of Cl(-) and TN to the groundwater. A low spatial correlation between the Cl(-) and NO3(-)-N concentrations in the groundwater and the on-land location of the dairy farms strengthened this assumption, despite the dairy waste lagoon being a point source for groundwater contamination by Cl(-) and NO3(-)-N. Mass balance calculations, for the vadose zone of the entire region, indicated that drying of the lagoons would decrease the regional groundwater salinization process (11% of the total Cl(-) load is stored under lagoons). A more considerable reduction in the groundwater contamination by NO3(-)-N is expected (25% of the NO3(-)-N load is stored under lagoons). Results demonstrate that analyzing vadose zone and groundwater data by spatial statistical analysis methods can significantly contribute to the understanding of the relations between groundwater contaminating sources, and to assessing appropriate remediation steps. Copyright © 2013 Elsevier Ltd. All rights reserved.

Fine Particle Sources and Cardiorespiratory Morbidity: An Application of Chemical Mass Balance and Factor Analytical Source-Apportionment Methods

PubMed Central

Sarnat, Jeremy A.; Marmur, Amit; Klein, Mitchel; Kim, Eugene; Russell, Armistead G.; Sarnat, Stefanie E.; Mulholland, James A.; Hopke, Philip K.; Tolbert, Paige E.

2008-01-01

Background Interest in the health effects of particulate matter (PM) has focused on identifying sources of PM, including biomass burning, power plants, and gasoline and diesel emissions that may be associated with adverse health risks. Few epidemiologic studies, however, have included source-apportionment estimates in their examinations of PM health effects. We analyzed a time-series of chemically speciated PM measurements in Atlanta, Georgia, and conducted an epidemiologic analysis using data from three distinct source-apportionment methods. Objective The key objective of this analysis was to compare epidemiologic findings generated using both factor analysis and mass balance source-apportionment methods. Methods We analyzed data collected between November 1998 and December 2002 using positive-matrix factorization (PMF), modified chemical mass balance (CMB-LGO), and a tracer approach. Emergency department (ED) visits for a combined cardiovascular (CVD) and respiratory disease (RD) group were assessed as end points. We estimated the risk ratio (RR) associated with same day PM concentrations using Poisson generalized linear models. Results There were significant, positive associations between same-day PM2.5 (PM with aero-dynamic diameter ≤ 2.5 μm) concentrations attributed to mobile sources (RR range, 1.018–1.025) and biomass combustion, primarily prescribed forest burning and residential wood combustion, (RR range, 1.024–1.033) source categories and CVD-related ED visits. Associations between the source categories and RD visits were not significant for all models except sulfate-rich secondary PM2.5 (RR range, 1.012–1.020). Generally, the epidemiologic results were robust to the selection of source-apportionment method, with strong agreement between the RR estimates from the PMF and CMB-LGO models, as well as with results from models using single-species tracers as surrogates of the source-apportioned PM2.5 values. Conclusions Despite differences among the source-apportionment methods, these findings suggest that modeled source-apportioned data can produce robust estimates of acute health risk. In Atlanta, there were consistent associations across methods between PM2.5 from mobile sources and biomass burning with both cardiovascular and respiratory ED visits, and between sulfate-rich secondary PM2.5 with respiratory visits. PMID:18414627

A Geochemical Mass-Balance Method for Base-Flow Separation, Upper Hillsborough River Watershed, West-Central Florida, 2003-2005 and 2009

USGS Publications Warehouse

Kish, G.R.; Stringer, C.E.; Stewart, M.T.; Rains, M.C.; Torres, A.E.

2010-01-01

Geochemical mass-balance (GMB) and conductivity mass-balance (CMB) methods for hydrograph separation were used to determine the contribution of base flow to total stormflow at two sites in the upper Hillsborough River watershed in west-central Florida from 2003-2005 and at one site in 2009. The chemical and isotopic composition of streamflow and precipitation was measured during selected local and frontal low- and high-intensity storm events and compared to the geochemical and isotopic composition of groundwater. Input for the GMB method included cation, anion, and stable isotope concentrations of surface water and groundwater, whereas input for the CMB method included continuous or point-sample measurement of specific conductance. The surface water is a calcium-bicarbonate type water, which closely resembles groundwater geochemically, indicating that much of the surface water in the upper Hillsborough River basin is derived from local groundwater discharge. This discharge into the Hillsborough River at State Road 39 and at Hillsborough River State Park becomes diluted by precipitation and runoff during the wet season, but retains the calcium-bicarbonate characteristics of Upper Floridan aquifer water. Field conditions limited the application of the GMB method to low-intensity storms but the CMB method was applied to both low-intensity and high-intensity storms. The average contribution of base flow to total discharge for all storms ranged from 31 to 100 percent, whereas the contribution of base flow to total discharge during peak discharge periods ranged from less than 10 percent to 100 percent. Although calcium, magnesium, and silica were consistent markers of Upper Floridan aquifer chemistry, their use in calculating base flow by the GMB method was limited because the frequency of point data collected in this study was not sufficient to capture the complete hydrograph from pre-event base-flow to post-event base-flow concentrations. In this study, pre-event water represented somewhat diluted groundwater. Streamflow conductivity integrates the concentrations of the major ions, and the logistics of acquiring specific conductance at frequent time intervals are less complicated than data collection, sample processing, shipment, and analysis of water samples in a laboratory. The acquisition of continuous specific conductance data reduces uncertainty associated with less-frequently collected geochemical point data.

Development of the ECLSS Sizing Analysis Tool and ARS Mass Balance Model Using Microsoft Excel

NASA Technical Reports Server (NTRS)

McGlothlin, E. P.; Yeh, H. Y.; Lin, C. H.

1999-01-01

The development of a Microsoft Excel-compatible Environmental Control and Life Support System (ECLSS) sizing analysis "tool" for conceptual design of Mars human exploration missions makes it possible for a user to choose a certain technology in the corresponding subsystem. This tool estimates the mass, volume, and power requirements of every technology in a subsystem and the system as a whole. Furthermore, to verify that a design sized by the ECLSS Sizing Tool meets the mission requirements and integrates properly, mass balance models that solve for component throughputs of such ECLSS systems as the Water Recovery System (WRS) and Air Revitalization System (ARS) must be developed. The ARS Mass Balance Model will be discussed in this paper.

Quantitation of tissue loss during prolonged space flight

NASA Technical Reports Server (NTRS)

Leonard, J. I.; Leach, C. S.; Rambaut, P. C.

1983-01-01

An analysis of data from the three Skylab missions was performed to assess the lean body mass (LBM) and fat components of inflight body weight loss. Six methods for determining LBM were employed based on changes in total body water, total body potassium, nitrogen balance, potassium balance, and stereophotometric-body density. Those based solely on body potassium, and potassium and nitrogen balances (when expressed as shifts from preflight control), consistently overestimated LBM loss unless appropriate corrections were made. The average results from the various methods indicated that of a mean inflight total body weight loss of 2.7 + or - 0.3 kg (SD) for all nine crewmembers, more than half (1.5 + or - 0.3 kg) can be attributed to loss of LBM (including 1.1 kg body water), the remainder (1.2 + or - 0.3 kg) being derived from fat stores. The reduction of LBM appeared to be complete after the first month of flight and thereafter was largely independent of mission duration, diet, and exercise.

Mercury mass balance in Lake Michigan--the knowns and unknowns

EPA Science Inventory

LM2-Mercury, a mercury mass balance model, was developed to simulate and evaluate the transport, fate, and biogeochemical transformations of mercury in Lake Michigan. The model simulates total suspended solids (TSS), disolved organic carbon (DOC), and total, elemental, divalent, ...

Composition of Meridiani Hematite-rich Spherules: A Mass-Balance Mixing-Model Approach

NASA Astrophysics Data System (ADS)

Jolliff, B. L.; Athena Science Team

2005-03-01

A mass-balance model using APXS data and microscopic images indicates that the composition of spherules ("blueberries"), found at the Meridiani site by the Mars Exploration Rover Opportunity and thought to be concretions, contain ~45-60 wt% hematite.

Delineating spring recharge areas in a fractured sandstone aquifer (Luxembourg) based on pesticide mass balance

NASA Astrophysics Data System (ADS)

Farlin, J.; Drouet, L.; Gallé, T.; Pittois, D.; Bayerle, M.; Braun, C.; Maloszewski, P.; Vanderborght, J.; Elsner, M.; Kies, A.

2013-06-01

A simple method to delineate the recharge areas of a series of springs draining a fractured aquifer is presented. Instead of solving the flow and transport equations, the delineation is reformulated as a mass balance problem assigning arable land in proportion to the pesticide mass discharged annually in a spring at minimum total transport cost. The approach was applied to the Luxembourg Sandstone, a fractured-rock aquifer supplying half of the drinking water for Luxembourg, using the herbicide atrazine. Predictions of the recharge areas were most robust in situations of strong competition by neighbouring springs while the catchment boundaries for isolated springs were extremely sensitive to the parameter controlling flow direction. Validation using a different pesticide showed the best agreement with the simplest model used, whereas using historical crop-rotation data and spatially distributed soil-leaching data did not improve predictions. The whole approach presents the advantage of integrating objectively information on land use and pesticide concentration in spring water into the delineation of groundwater recharge zones in a fractured-rock aquifer.

Numerical simulation of advective-dispersive multisolute transport with sorption, ion exchange and equilibrium chemistry

USGS Publications Warehouse

Lewis, F.M.; Voss, C.I.; Rubin, Jacob

1986-01-01

A model was developed that can simulate the effect of certain chemical and sorption reactions simultaneously among solutes involved in advective-dispersive transport through porous media. The model is based on a methodology that utilizes physical-chemical relationships in the development of the basic solute mass-balance equations; however, the form of these equations allows their solution to be obtained by methods that do not depend on the chemical processes. The chemical environment is governed by the condition of local chemical equilibrium, and may be defined either by the linear sorption of a single species and two soluble complexation reactions which also involve that species, or binary ion exchange and one complexation reaction involving a common ion. Partial differential equations that describe solute mass balance entirely in the liquid phase are developed for each tenad (a chemical entity whose total mass is independent of the reaction process) in terms of their total dissolved concentration. These equations are solved numerically in two dimensions through the modification of an existing groundwater flow/transport computer code. (Author 's abstract)

[Sarcopenic obesity and physical fitness in octogenarians: the multi-center EXERNET Project].

PubMed

Muñoz-Arribas, Alberto; Mata, Esmeralda; Pedrero-Chamizo, Raquel; Espino, Luis; Gusi, Narcis; Villa, Gerardo; Gonzalez-Gross, Marcela; Casajús, José Antonio; Ara, Ignacio; Gómez-Cabello, Alba

2013-11-01

The aim of this study was to analyze the usefulness of different fitness test to detect the risk of sarcopenic obesity (SO) in octogenarian people. 306 subjects (76 men, 230 women) with a mean age of 82.5 ± 2.3 years from the Multi-center EXERNET Project sample fulfilled the inclusion criteria. Body composition was assessed in all subjects by bioelectrical impedance. Four groups were created based on the percentage of fat mass and muscle mass: 1) normal, 2) high fat mass, 3) low muscle mass and 4) SO. Physical fitness was assessed using 8 different tests modified from the batteries “Senior Fitness Test” and Eurofit (EXERNET battery). The risk of suffering SO depending on the fitness level was studied by logistic regression. Among the studied physical fitness tests, those that better predicted the risk of SO were leg strength, arm strength, agility, walking speed and balance in men; 95% CI [(0.606-0.957) (0.496-0.882), (0.020-2.014), (0.17-1.39), (0.913-1.002), all p < 0.05, except balance test (p = 0.07)] and balance test and agility in women; (95% CI [(0.928-1.002) (0.983-1.408), (both p = 0.07)]. Adequate levels of physical fitness are associated with a lower risk of SO. Some easy fitness tests seem to be useful for the detection of SO in those cases where the body-composition required methods for diagnosis are not available. Copyright AULA MEDICA EDICIONES 2013. Published by AULA MEDICA. All rights reserved.

Optimized balance rehabilitation training strategy for the elderly through an evaluation of balance characteristics in response to dynamic motions

PubMed Central

Jung, HoHyun; Chun, Keyoung Jin; Hong, Jaesoo; Lim, Dohyung

2015-01-01

Balance is important in daily activities and essential for maintaining an independent lifestyle in the elderly. Recent studies have shown that balance rehabilitation training can improve the balance ability of the elderly, and diverse balance rehabilitation training equipment has been developed. However, there has been little research into optimized strategies for balance rehabilitation training. To provide an optimized strategy, we analyzed the balance characteristics of participants in response to the rotation of a base plate on multiple axes. Seven male adults with no musculoskeletal or nervous system-related diseases (age: 25.5±1.7 years; height: 173.9±6.4 cm; body mass: 71.3±6.5 kg; body mass index: 23.6±2.4 kg/m2) were selected to investigate the balance rehabilitation training using customized rehabilitation equipment. Rotation of the base plate of the equipment was controlled to induce dynamic rotation of participants in the anterior–posterior, right-diagonal, medial–lateral, and left-diagonal directions. We used a three-dimensional motion capture system employing infrared cameras and the Pedar Flexible Insoles System to characterize the major lower-extremity joint angles, center of body mass, and center of pressure. We found statistically significant differences between the changes in joint angles in the lower extremities in response to dynamic rotation of the participants (P<0.05). The maximum was greater with anterior–posterior and medial–lateral dynamic rotation than with that in other directions (P<0.05). However, there were no statistically significant differences in the frequency of center of body mass deviations from the base of support (P>0.05). These results indicate that optimizing rotation control of the base plate of balance rehabilitation training equipment to induce anterior–posterior and medial–lateral dynamic rotation preferentially can lead to effective balance training. Additional tests with varied speeds and ranges of angles of base plate rotation are expected to be useful as well as an analysis of the balance characteristics considering a balance index that reflects the muscle activity and cooperative characteristics. PMID:26508847

Effects of easy-to-use protein-rich energy bar on energy balance, physical activity and performance during 8 days of sustained physical exertion.

PubMed

Tanskanen, Minna M; Westerterp, Klaas R; Uusitalo, Arja L; Atalay, Mustafa; Häkkinen, Keijo; Kinnunen, Hannu O; Kyröläinen, Heikki

2012-01-01

Previous military studies have shown an energy deficit during a strenuous field training course (TC). This study aimed to determine the effects of energy bar supplementation on energy balance, physical activity (PA), physical performance and well-being and to evaluate ad libitum fluid intake during wintertime 8-day strenuous TC. Twenty-six men (age 20±1 yr.) were randomly divided into two groups: The control group (n = 12) had traditional field rations and the experimental (Ebar) group (n = 14) field rations plus energy bars of 4.1 MJ•day(-1). Energy (EI) and water intake was recorded. Fat-free mass and water loss were measured with deuterium dilution and elimination, respectively. The energy expenditure was calculated using the intake/balance method and energy availability as (EI/estimated basal metabolic rate). PA was monitored using an accelerometer. Physical performance was measured and questionnaires of upper respiratory tract infections (URTI), hunger and mood state were recorded before, during and after TC. Ebar had a higher EI and energy availability than the controls. However, decreases in body mass and fat mass were similar in both groups representing an energy deficit. No differences were observed between the groups in PA, water balance, URTI symptoms and changes in physical performance and fat-free mass. Ebar felt less hunger after TC than the controls and they had improved positive mood state during the latter part of TC while controls did not. Water deficit associated to higher PA. Furthermore, URTI symptoms and negative mood state associated negatively with energy availability and PA. An easy-to-use protein-rich energy bars did not prevent energy deficit nor influence PA during an 8-day TC. The high content of protein in the bars might have induced satiation decreasing energy intake from field rations. PA and energy intake seems to be primarily affected by other factors than energy supplementation such as mood state.

LINKING GREAT WATERSHEDS WITH LAKE MICHIGAN: THE LAKE MICHIGAN MASS BALANCE STUDY

EPA Science Inventory

An overview of the Lake Michigan Mass Balance Study -- which is focusing on atrazine, PCBs, nutrients, suspended solids, trans-nonachlor, and mercury. The relative contribution of contaminants to Lake Michigan will be examined for all major watersheds in the basin. - - - Further ...

LAKE MICHIGAN MASS BALANCE STUDY: PROGNOSIS FOR PCBS

EPA Science Inventory

The Lake Michigan Mass Balance Study was conducted to measure and model nutrients, atrazine, PCBs, trans-nonachlor, and mercury to gain a better understanding of the transport and fate of these substances within the system and to aid managers in the environmental decision-making ...

Influence of foundation mass and surface roughness on dynamic response of beam on dynamic foundation subjected to the moving load

NASA Astrophysics Data System (ADS)

Tran Quoc, Tinh; Khong Trong, Toan; Luong Van, Hai

2018-04-01

In this paper, Improved Moving Element Method (IMEM) is used to analyze the dynamic response of Euler-Bernoulli beam structures on the dynamic foundation model subjected to the moving load. The effects of characteristic foundation model parameters such as Winkler stiffness, shear layer based on the Pasternak model, viscoelastic dashpot and characteristic parameter of mass on foundation. Beams are modeled by moving elements while the load is fixed. Based on the principle of the publicly virtual balancing and the theory of moving element method, the motion differential equation of the system is established and solved by means of the numerical integration based on the Newmark algorithm. The influence of mass on foundation and the roughness of the beam surface on the dynamic response of beam are examined in details.

In-Situ Mass Balance Measurements and Morphology Study of Patsio Glacier, Himachal Pradesh, Western Himalaya

NASA Astrophysics Data System (ADS)

Angchuk, T.; AL, R.; Mandal, A.; Soheb, M.; Bahuguna, I. M.; Singh, V.; Linda, A.

2016-12-01

The present ongoing study is oriented to do the detailed study of the Patsio glacier which is in the Bhaga Basin, Lahaul, Himachal Pradesh. Patsio glacier is a compound valley glacier survived by two prominent tributaries namely Eastern and Western. The two tributaries are facing opposite to each other. The Western tributary facing almost eastward shows higher melting as compared to Eastern tributary facing northwest. This is probably due to solar radiation and sunshine hour, as Western tributary receives high solar radiation and for longer duration. A series of supraglacial lakes which were connected to each other through supra channels were observed on the upper part of the ablation zone at an altitude range of 5100 m and 5300 m amsl. A dead ice covered with thick debris was observed below the current terminus. Despite the large variability of the mass balance in the different seasons Patsio glacier annual balance for the year 2012-2013 was found to be 0.04 ± 0.40 m w.e. the low values signifies that glacier has lost significant amount of mass in recent past and now it is near to the equilibrium state. Seasonal mass balance of Patsio glacier has shown wide range of variability in the mass balances. Patsio glacier receives most of the accumulation during the winter months and duration is long whereas, ablation season is short but quite significant. Monthly and daily variation has depicted that peak ablation months are July and August. The daily ablation in the month of August 2013 was found to be around 5 cm per day, probably due to air temperature. To have a clear picture of the meteorological parameters and its relation with glacier an AWS has set up on the Patsio glacier at an altitude of 5050 m amsl in June 2014. Seasonal mass balance gradients show that gradient was high during the early and late ablation seasons as compared to peak ablation season. The mass balance for the year 2010-2011 was slightly positive.

Gulkana Glacier, Alaska-Mass balance, meteorology, and water measurements, 1997-2001

USGS Publications Warehouse

March, Rod S.; O'Neel, Shad

2011-01-01

The measured winter snow, maximum winter snow, net, and annual balances for 1997-2001 in the Gulkana Glacier basin are determined at specific points and over the entire glacier area using the meteorological, hydrological, and glaciological data. We provide descriptions of glacier geometry to aid in estimation of conventional and reference surface mass balances and descriptions of ice motion to aid in the understanding of the glacier's response to its changing geometry. These data provide annual estimates for area altitude distribution, equilibrium line altitude, and accumulation area ratio during the study interval. New determinations of historical area altitude distributions are given for 1900 and annually from 1966 to 2001. As original weather instrumentation is nearing the end of its deployment lifespan, we provide new estimates of overlap comparisons and precipitation catch efficiency. During 1997-2001, Gulkana Glacier showed a continued and accelerated negative mass balance trend, especially below the equilibrium line altitude where thinning was pronounced. Ice motion also slowed, which combined with the negative mass balance, resulted in glacier retreat under a warming climate. Average annual runoff augmentation by glacier shrinkage for 1997-2001 was 25 percent compared to the previous average of 13 percent, in accordance with the measured glacier volume reductions.

Particle-Size-Grouping Model of Precipitation Kinetics in Microalloyed Steels

NASA Astrophysics Data System (ADS)

Xu, Kun; Thomas, Brian G.

2012-03-01

The formation, growth, and size distribution of precipitates greatly affects the microstructure and properties of microalloyed steels. Computational particle-size-grouping (PSG) kinetic models based on population balances are developed to simulate precipitate particle growth resulting from collision and diffusion mechanisms. First, the generalized PSG method for collision is explained clearly and verified. Then, a new PSG method is proposed to model diffusion-controlled precipitate nucleation, growth, and coarsening with complete mass conservation and no fitting parameters. Compared with the original population-balance models, this PSG method saves significant computation and preserves enough accuracy to model a realistic range of particle sizes. Finally, the new PSG method is combined with an equilibrium phase fraction model for plain carbon steels and is applied to simulate the precipitated fraction of aluminum nitride and the size distribution of niobium carbide during isothermal aging processes. Good matches are found with experimental measurements, suggesting that the new PSG method offers a promising framework for the future development of realistic models of precipitation.

Field measurements and modeling to resolve m2 to km2 CH4 emissions for a complex urban source: An Indiana landfill study

USDA-ARS?s Scientific Manuscript database

Large uncertainties for landfill CH4 emissions due to spatial and temporal variabilities remain unresolved by short-term field campaigns and historic GHG inventory models. Using four field methods (aircraft-based mass balance, tracer correlation, vertical radial plume mapping, and static chambers) ...

Mass balance of Mars' residual south polar cap from CTX images and other data

NASA Astrophysics Data System (ADS)

Thomas, P. C.; Calvin, W.; Cantor, B.; Haberle, R.; James, P. B.; Lee, S. W.

2016-04-01

Erosion of pits in the residual south polar cap (RSPC) of Mars concurrent with deposition and fluctuating cap boundaries raises questions about the mass balance and long term stability of the cap. Determining a mass balance by measurement of a net gain or loss of atmospheric CO2 by direct pressure measurements (Haberle, R.M. et al. [2014]. Secular climate change on Mars: An update using one Mars year of MSL pressure data. American Geophysical Union (Fall). Abstract 3947), although perhaps the most direct method, has so far given ambiguous results. Estimating volume changes from imaging data faces challenges, and has previously been attempted only in isolated areas of the cap. In this study we use 6 m/pixel Context Imager (CTX) data from Mars year 31 to map all the morphologic units of the RSPC, expand the measurement record of pit erosion rates, and use high resolution images to place limits on vertical changes in the surface of the residual cap. We find the mass balance in Mars years 9-31 to be -6 to +4 km3/♂y, or roughly -0.039% to +0.026% of the mean atmospheric CO2 mass/♂y. The indeterminate sign results chiefly from uncertainty in the amounts of deposition or erosion on the upper surfaces of deposits (as opposed to scarp retreat). Erosion and net deposition in this period appear to be controlled by summertime planetary scale dust events, the largest occurring in MY 9, another, smaller one in MY 28. The rates of erosion and the deposition observed since MY 9 appear to be consistent with the types of deposits and erosional behavior found in most of the residual cap. However, small areas (<10%) of the cap are distinguished by their greater thickness, polygonal troughs, and embayed contacts with thinner units. These deposits may require extended periods (>100 ♂y) of depositional and/or erosional conditions different from those occurring in the period since MY 9, although these environmental differences could be subtle.

Elevation Change of Drangajokull, Iceland, from Cloud-Cleared ICESat Repeat Profiles and GPS Ground-Survey Data

NASA Technical Reports Server (NTRS)

Shuman, Christopher A.; Sigurdsson, Oddur; Williams, Richard, Jr.; Hall, Dorothy K.

2009-01-01

Located on the Vestfirdir Northwest Fjords), DrangaJokull is the northernmost ice map in Iceland. Currently, the ice cap exceeds 900 m in elevation and covered an area of approx.l46 sq km in August 2004. It was about 204 sq km in area during 1913-1914 and so has lost mass during the 20th century. Drangajokull's size and accessibility for GPS surveys as well as the availability of repeat satellite altimetry profiles since late 2003 make it a good subject for change-detection analysis. The ice cap was surveyed by four GPS-equipped snowmobiles on 19-20 April 2005 and has been profiled in two places by Ice, Cloud. and land Elevation Satellite (ICESat) 'repeat tracks,' fifteen times from late to early 2009. In addition, traditional mass-balance measurements have been taken seasonally at a number of locations across the ice cap and they show positive net mass balances in 2004/2005 through 2006/2007. Mean elevation differences between the temporally-closest ICESat profiles and the GPS-derived digital-elevation model (DEM)(ICESat - DEM) are about 1.1 m but have standard deviations of 3 to 4 m. Differencing all ICESat repeats from the DEM shows that the overall elevation difference trend since 2003 is negative with losses of as much as 1.5 m/a from same season to same season (and similar elevation) data subsets. However, the mass balance assessments by traditional stake re-measurement methods suggest that the elevation changes where ICESat tracks 0046 and 0307 cross Drangajokull are not representative of the whole ice cap. Specifically, the area has experienced positive mass balance years during the time frame when ICESat data indicates substantial losses. This analysis suggests that ICESat-derived elevations may be used for multi-year change detection relative to other data but suggests that large uncertainties remain. These uncertainties may be due to geolocation uncertainty on steep slopes and continuing cloud cover that limits temporal and spatial coverage across the area.

An Analysis of Mass Balance of Chilean Glaciers

NASA Astrophysics Data System (ADS)

Ambinakudige, S.; Tetteh, L.

2013-12-01

Glaciers in Chile range from very small glacierets found on the isolated volcanoes of northern Chile to the 13,000 sq.km Southern Patagonian Ice Field. Regular monitoring of these glaciers is very important as they are considered as sensitive indicators of climate change. Millions of people's lives are dependent on these glaciers for fresh water and irrigation purpose. In this study, mass balances of several Chilean glaciers were estimated using Aster satellite images between 2007 and 2012. Highly accurate DEMs were created with supplementary information from IceSat data. The result indicated a negative mass balance for many glaciers indicating the need for further monitoring of glaciers in the Andes.

Enforcing elemental mass and energy balances for reduced order models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma, J.; Agarwal, K.; Sharma, P.

2012-01-01

Development of economically feasible gasification and carbon capture, utilization and storage (CCUS) technologies requires a variety of software tools to optimize the designs of not only the key devices involved (e., g., gasifier, CO{sub 2} adsorber) but also the entire power generation system. High-fidelity models such as Computational Fluid Dynamics (CFD) models are capable of accurately simulating the detailed flow dynamics, heat transfer, and chemistry inside the key devices. However, the integration of CFD models within steady-state process simulators, and subsequent optimization of the integrated system, still presents significant challenges due to the scale differences in both time and length,more » as well the high computational cost. A reduced order model (ROM) generated from a high-fidelity model can serve as a bridge between the models of different scales. While high-fidelity models are built upon the principles of mass, momentum, and energy conservations, ROMs are usually developed based on regression-type equations and hence their predictions may violate the mass and energy conservation laws. A high-fidelity model may also have the mass and energy balance problem if it is not tightly converged. Conservations of mass and energy are important when a ROM is integrated to a flowsheet for the process simulation of the entire chemical or power generation system, especially when recycle streams are connected to the modeled device. As a part of the Carbon Capture Simulation Initiative (CCSI) project supported by the U.S. Department of Energy, we developed a software framework for generating ROMs from CFD simulations and integrating them with Process Modeling Environments (PMEs) for system-wide optimization. This paper presents a method to correct the results of a high-fidelity model or a ROM such that the elemental mass and energy are conserved perfectly. Correction factors for the flow rates of individual species in the product streams are solved using a minimization algorithm based on Lagrangian multiplier method. Enthalpies of product streams are also modified to enforce the energy balance. The approach is illustrated for two ROMs, one based on a CFD model of an entrained-flow gasifier and the other based on the CFD model of a multiphase CO{sub 2} adsorber.« less

Estimating Temporal Redistribution of Surface Melt Water into Upper Stratigraphy of the Juneau Icefield, Alaska

NASA Astrophysics Data System (ADS)

Wilner, J.; Smith, B.; Moore, T.; Campbell, S. W.; Slavin, B. V.; Hollander, J.; Wolf, J.

2015-12-01

The redistribution of winter accumulation from surface melt into firn or deeper layers (i.e. internal accumulation) remains a poorly understood component of glacier mass balance. Winter accumulation is usually quantified prior to summer melt, however the time window between accumulation and the onset of melt is minimal so this is not always possible. Studies which are initiated following the onset of summer melt either neglect sources of internal accumulation or attempt to estimate melt (and therefore winter accumulation uncertainty) through a variety of modeling methods. Here, we used ground-penetrating radar (GPR) repeat common midpoint (CMP) surveys with supporting common offset surveys, mass balance snow pits, and probing to estimate temporal changes in water content within the winter accumulation and firn layers of the southern Juneau Icefield, Alaska. In temperate glaciers, radio-wave velocity is primarily dependent on water content and snow or firn density. We assume density changes are temporally slow relative to water flow through the snow and firn pack, and therefore infer that changing radio-wave velocities measured by successive CMP surveys result from flux in surface melt through deeper layers. Preliminary CMP data yield radio-wave velocities of 0.15 to 0.2 m/ns in snowpack densities averaging 0.56 g cm-3, indicating partially to fully saturated snowpack (4-9% water content). Further spatial-temporal analysis of CMP surveys is being conducted. We recommend that repeat CMP surveys be conducted over a longer time frame to estimate stratigraphic water redistribution between the end of winter accumulation and maximum melt season. This information could be incorporated into surface energy balance models to further understanding of the influence of internal accumulation on glacier mass balance.

THE LAKE MICHIGAN MASS BALANCE PROJECT: QUALITY ASSURANCE PLAN FOR MATHEMATICAL MODELLING

EPA Science Inventory

This report documents the quality assurance process for the development and application of the Lake Michigan Mass Balance Models. The scope includes the overall modeling framework as well as the specific submodels that are linked to form a comprehensive synthesis of physical, che...

40 CFR 1065.307 - Linearity verification.

Code of Federal Regulations, 2014 CFR

2014-07-01

... measurement (such as a scale, balance, or mass comparator) at the inlet to the fuel-measurement system. Use a... nitrogen. Select gas divisions that you typically use. Use a selected gas division as the measured value.... (9) Mass. For linearity verification for gravimetric PM balances, use external calibration weights...

Great Lakes water quality scenario models: Operational feasibility -Lake Michigan Mass Balance models

EPA Science Inventory

An overview of the Lake Michigan Mass Balance models were provided (eutrophication/nutrients, atrazine, mercury, and PCBs) with emphasis on the PCB model post-audit and forecast for Lake Trout. Provided were modeling construct, model description, and primary results. An assessm...

OVERVIEW AND STATUS OF LAKE MICHIGAN MASS BALANCE MODELLING PROJECT

EPA Science Inventory

With most of the data available from the Lake Michigan Mass Balance Project field program, the modeling efforts have begun in earnest. The tributary and atmospheric load estimates are or will be completed soon, so realistic simulations for calibration are beginning. A Quality Ass...

ATMOSPHERIC MERCURY DEPOSITION TO LAKE MICHIGAN DURING THE LAKE MICHIGAN MASS BALANCE STUDY

EPA Science Inventory

Wet and dry mercury (Hg) deposition were calculated to Lake Michigan using a hybrid receptor modeling framework. The model utilized mercury monitoring data collected during the Lake Michigan Mass Balance Study and the Atmospheric Exchange Over Lakes and Oceans Study together w...

A POLLUTION REDUCTION METHODOLOGY FOR CHEMICAL PROCESS SIMULATORS

EPA Science Inventory

A pollution minimization methodology was developed for chemical process design using computer simulation. It is based on a pollution balance that at steady state is used to define a pollution index with units of mass of pollution per mass of products. The pollution balance has be...

Multi-year analysis of distributed glacier mass balance modelling and equilibrium line altitude on King George Island, Antarctic Peninsula

NASA Astrophysics Data System (ADS)

Falk, Ulrike; López, Damián A.; Silva-Busso, Adrián

2018-04-01

The South Shetland Islands are located at the northern tip of the Antarctic Peninsula (AP). This region was subject to strong warming trends in the atmospheric surface layer. Surface air temperature increased about 3 K in 50 years, concurrent with retreating glacier fronts, an increase in melt areas, ice surface lowering and rapid break-up and disintegration of ice shelves. The positive trend in surface air temperature has currently come to a halt. Observed surface air temperature lapse rates show a high variability during winter months (standard deviations up to ±1.0 K (100 m)-1) and a distinct spatial heterogeneity reflecting the impact of synoptic weather patterns. The increased mesocyclonic activity during the wintertime over the past decades in the study area results in intensified advection of warm, moist air with high temperatures and rain and leads to melt conditions on the ice cap, fixating surface air temperatures to the melting point. Its impact on winter accumulation results in the observed negative mass balance estimates. Six years of continuous glaciological measurements on mass balance stake transects as well as 5 years of climatological data time series are presented and a spatially distributed glacier energy balance melt model adapted and run based on these multi-year data sets. The glaciological surface mass balance model is generally in good agreement with observations, except for atmospheric conditions promoting snow drift by high wind speeds, turbulence-driven snow deposition and snow layer erosion by rain. No drift in the difference between simulated mass balance and mass balance measurements can be seen over the course of the 5-year model run period. The winter accumulation does not suffice to compensate for the high variability in summer ablation. The results are analysed to assess changes in meltwater input to the coastal waters, specific glacier mass balance and the equilibrium line altitude (ELA). The Fourcade Glacier catchment drains into Potter cove, has an area of 23.6 km2 and is glacierized to 93.8 %. Annual discharge from Fourcade Glacier into Potter Cove is estimated to q ¯ = 25±6 hm3 yr-1 with the standard deviation of 8 % annotating the high interannual variability. The average ELA calculated from our own glaciological observations on Fourcade Glacier over the time period 2010 to 2015 amounts to 260±20 m. Published studies suggest rather stable conditions of slightly negative glacier mass balance until the mid-1980s with an ELA of approx. 150 m. The calculated accumulation area ratio suggests dramatic changes in the future extent of the inland ice cap for the South Shetland Islands.

Efficient fractionation of spruce by SO(2)-ethanol-water treatment: closed mass balances for carbohydrates and sulfur.

PubMed

Iakovlev, Mikhail; van Heiningen, Adriaan

2012-08-01

SO(2)-ethanol-water (SEW) lignocellulosic fractionation has the potential to overcome the present techno-economic barriers that hinder the commercial implementation of renewable transportation fuel production. In this study, SEW fractionation of spruce wood chips is examined for its ability to separate the main wood components, hemicelluloses, lignin, and cellulose, and the potential to recover SO(2) and ethanol from the spent fractionation liquid. Therefore, overall sulfur and carbohydrate mass balances are established. 95-97 % of the charged SO(2) remains in the liquid and can be fully recovered by distillation. During fractionation, hemicelluloses and lignin are effectively dissolved, whereas cellulose is preserved in the solid (fibre) phase. Hemicelluloses are hydrolysed, producing up to 50 % monomeric sugars, whereas dehydration and oxidation of carbohydrates are insignificant. The latter is proven by the closed carbohydrate material balances as well as by the near absence of corresponding by-products (furfural, hydroxymethylfurfural (HMF) and aldonic acids). In addition, acid methanolysis/GC and acid hydrolysis/high performance anion exchange chromatography (HPAEC) methods for the carbohydrate determination are compared. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Multi channel thermal hydraulic analysis of gas cooled fast reactor using genetic algorithm

NASA Astrophysics Data System (ADS)

Drajat, R. Z.; Su'ud, Z.; Soewono, E.; Gunawan, A. Y.

2012-05-01

There are three analyzes to be done in the design process of nuclear reactor i.e. neutronic analysis, thermal hydraulic analysis and thermodynamic analysis. The focus in this article is the thermal hydraulic analysis, which has a very important role in terms of system efficiency and the selection of the optimal design. This analysis is performed in a type of Gas Cooled Fast Reactor (GFR) using cooling Helium (He). The heat from nuclear fission reactions in nuclear reactors will be distributed through the process of conduction in fuel elements. Furthermore, the heat is delivered through a process of heat convection in the fluid flow in cooling channel. Temperature changes that occur in the coolant channels cause a decrease in pressure at the top of the reactor core. The governing equations in each channel consist of mass balance, momentum balance, energy balance, mass conservation and ideal gas equation. The problem is reduced to finding flow rates in each channel such that the pressure drops at the top of the reactor core are all equal. The problem is solved numerically with the genetic algorithm method. Flow rates and temperature distribution in each channel are obtained here.

Energy balance and mass conservation in reduced order models of fluid flows

NASA Astrophysics Data System (ADS)

Mohebujjaman, Muhammad; Rebholz, Leo G.; Xie, Xuping; Iliescu, Traian

2017-10-01

In this paper, we investigate theoretically and computationally the conservation properties of reduced order models (ROMs) for fluid flows. Specifically, we investigate whether the ROMs satisfy the same (or similar) energy balance and mass conservation as those satisfied by the Navier-Stokes equations. All of our theoretical findings are illustrated and tested in numerical simulations of a 2D flow past a circular cylinder at a Reynolds number Re = 100. First, we investigate the ROM energy balance. We show that using the snapshot average for the centering trajectory (which is a popular treatment of nonhomogeneous boundary conditions in ROMs) yields an incorrect energy balance. Then, we propose a new approach, in which we replace the snapshot average with the Stokes extension. Theoretically, the Stokes extension produces an accurate energy balance. Numerically, the Stokes extension yields more accurate results than the standard snapshot average, especially for longer time intervals. Our second contribution centers around ROM mass conservation. We consider ROMs created using two types of finite elements: the standard Taylor-Hood (TH) element, which satisfies the mass conservation weakly, and the Scott-Vogelius (SV) element, which satisfies the mass conservation pointwise. Theoretically, the error estimates for the SV-ROM are sharper than those for the TH-ROM. Numerically, the SV-ROM yields significantly more accurate results, especially for coarser meshes and longer time intervals.

Analysis of a GRACE Global Mascon Solution for Gulf of Alaska Glaciers

NASA Technical Reports Server (NTRS)

Arendt, Anthony; Luthcke, Scott B.; Gardner, Alex; O'Neel, Shad; Hill, David; Moholdt, Geir; Abdalati, Waleed

2013-01-01

We present a high-resolution Gravity Recovery and Climate Experiment (GRACE) mascon solution for Gulf of Alaska (GOA) glaciers and compare this with in situ glaciological, climate and other remote-sensing observations. Our GRACE solution yields a GOA glacier mass balance of -6511 Gt a(exp.-1) for the period December 2003 to December 2010, with summer balances driving the interannual variability. Between October/November 2003 and October 2009 we obtain a mass balance of -6111 Gt a(exp. -1) from GRACE, which compares well with -6512 Gt a(exp. -1) from ICESat based on hypsometric extrapolation of glacier elevation changes. We find that mean summer (June-August) air temperatures derived from both ground and lower-troposphere temperature records were good predictors of GRACE-derived summer mass balances, capturing 59% and 72% of the summer balance variability respectively. Large mass losses during 2009 were likely due to low early melt season surface albedos, measured by the Moderate Resolution Imaging Spectroradiometer (MODIS) and likely associated with the 31 March 2009 eruption of Mount Redoubt, southwestern Alaska. GRACE data compared well with in situ measurements atWolverine Glacier (maritime Alaska), but poorly with those at Gulkana Glacier (interior Alaska). We conclude that, although GOA mass estimates from GRACE are robust over the entire domain, further constraints on subregional and seasonal estimates are necessary to improve fidelity to ground observations.

Analysis of a GRACE global mascon solution for Gulf of Alaska glaciers

USGS Publications Warehouse

Arendt, Anthony; Luthcke, Scott; Gardner, Alex; O'Neel, Shad; Hill, David; Moholdt, Geir; Abdalati, Waleed

2013-01-01

We present a high-resolution Gravity Recovery and Climate Experiment (GRACE) mascon solution for Gulf of Alaska (GOA) glaciers and compare this with in situ glaciological, climate and other remote-sensing observations. Our GRACE solution yields a GOA glacier mass balance of –65 ± 11 Gt a–1 for the period December 2003 to December 2010, with summer balances driving the interannual variability. Between October/November 2003 and October 2009 we obtain a mass balance of –61 ± 11 Gt a–1 from GRACE, which compares well with –65 ± 12 Gt a–1 from ICESat based on hypsometric extrapolation of glacier elevation changes. We find that mean summer (June–August) air temperatures derived from both ground and lower-troposphere temperature records were good predictors of GRACE-derived summer mass balances, capturing 59% and 72% of the summer balance variability respectively. Large mass losses during 2009 were likely due to low early melt season surface albedos, measured by the Moderate Resolution Imaging Spectroradiometer (MODIS) and likely associated with the 31 March 2009 eruption of Mount Redoubt, southwestern Alaska. GRACE data compared well with in situ measurements at Wolverine Glacier (maritime Alaska), but poorly with those at Gulkana Glacier (interior Alaska). We conclude that, although GOA mass estimates from GRACE are robust over the entire domain, further constraints on subregional and seasonal estimates are necessary to improve fidelity to ground observations.

Mass balance approaches to understanding evolution of dripwater chemistry

NASA Astrophysics Data System (ADS)

Fairchild, I. J.; Baker, A.; Andersen, M. S.; Treble, P. C.

2015-12-01

Forward and inverse modelling of dripwater chemistry is a fast-developing area in speleothem science. Such approaches can incorporate theoretical, parameterized or observed relationships between forcing factors and water composition, but at the heart is mass balance: a fundamental principle that provides important constraints. Mass balance has been used in speleothem studies to trace the evolution of dissolved inorganic carbon and carbon isotopes from soil to cave, and to characterize the existence and quantification of prior calcite precipitation (PCP) based on ratios of Mg and Sr to Ca. PCP effects can dominate slow drips, whereas fast drips are more likely to show a residual variability linked to soil-biomass processes. A possible configuration of a more complete mass balance model is illustrated in the figure. Even in humid temperate climates, evapotranspiration can be 50% of total atmospheric precipitation leading to substantially raised salt contents and there can be significant exchange with biomass. In more arid settings, at least seasonal soil storage of salts is likely. Golgotha Cave in SW Australia is in a Mediterranean climate with a strong summer soil moisture deficit. The land surface is forested leading to large ion fluxes related to vegetation. There are also periodic disturbances related to fire. Mass balance approaches have been applied to an 8-year monitoring record. Inter-annual trends of elements coprecipitated in speleothems from fast drips are predicted to be dominated by biomass effects.

On Land Ice Mass Change in Southernmost South America, Antarctic Peninsula and Coastal Antarctica consistent with GRACE, GPS and Reconstructed Ice History for Past 1000 years.

NASA Astrophysics Data System (ADS)

Ivins, Erik; Wiese, David; Watkins, Michael; Yuan, Dah-Ning; Landerer, Felix; Simms, Alex; Boening, Carmen

2014-05-01

The improved spatial coverage provided by high-quality Global Positioning System observing systems on exposed bedrock has allowed these space geodetic experiments to play an increasingly important role in constraining both glacial isostatic adjustment (GIA) processes and viscoelastic responses to present-day glacial mass changes (PGMC). Improved constraints on models of ice mass change in the Southern Hemisphere at present-day, during the Little Ice Age, and during the Late Holocene are invaluable for reconciling climate and sea-level variability on a global scale during the present solar radiation forcing and Milankovic orbital configuration. Studies by Jacobs et al. (1992), Whitehouse et al. (2012), King et al. (2012), Boening et al (2012), and others, support the contention that GRACE observations of both GIA and PGMC in the Southern Hemisphere are dominated by the geography and climate of coastal environments. This makes the proper masking of those environments for GRACE-determinations of secular mass balance especially sensitive, and downscaling, rescaling, and use of correlation mascon methods a non-trivial part of the analysis. Here we employ two analysis methods to determine the mass balances of the Antarctic Peninsula and Patagonia and incorporate GPS observations of ongoing uplift for GIA correction into both. Using data that roughly span 2002-2013, we determine -25 ± 5 Gt/yr for the uncorrected Antarctic Peninsula (AP) and -12 Gt/yr for southern Patagonia and the Cordillera Darwin (PCD). With corrections for GIA these are increased to -34 ± 8 Gt/yr for AP and -22 ± 6 Gt/yr for PCD.

Simulating ice thickness and velocity evolution of Upernavik Isstrøm 1849-2017 with ISSM

NASA Astrophysics Data System (ADS)

Haubner, K.; Box, J.; Schlegel, N.; Larour, E. Y.; Morlighem, M.; Solgaard, A.; Kjeldsen, K. K.; Larsen, S. H.; Rignot, E. J.; Dupont, T. K.; Kjaer, K. H.

2017-12-01

Tidewater terminus changes have a significant influence on glacier velocity and mass balance and impact therefore Greenland's ice mass balance. Improving glacier front changes in ice sheet models helps understanding the processes that are driving glacier mass changes and improves predictions on Greenland's mass loss. We use the level set based moving boundary capability (Bondzio et al., 2016) included in the Ice Sheet System Model ISSM to reconstruct velocity and thickness changes on Upernavik Isstrøm, Greenland from 1849 to 2017. During the simulation, we use various data sets. For the model initialization, trim line data and an observed calving front position determine the shape of the ice surface elevation. The terminus changes are prescribed by observations. Data sets like the GIMP DEM, ArcticDEM, IceBridge surface elevation and ice surface velocities from the ESA project CCI and NASA project MEaSUREs help evaluating the simulation performance. The simulation is sensitive to the prescribed terminus changes, showing an average acceleration along the three flow lines between 50% and 190% from 1849 to 2017. Simulated ice surface velocity and elevation between 1990 and 2012 are within +/-20% of observations (GIMP, ArcticDEM, IceBridge, CCI and MEaSUREs). Simulated mass changes indicate increased dynamical ice loss from 1932 onward, amplified by increased negative SMB anomalies after 1998. More detailed information about methods and findings can be found in Haubner et al., 2017 (in TC discussion, describing simulation results between 1849-2012). Future goals are the comparison of ice surface velocity changes simulated with prescribed terminus retreat against other retreat schemes (Morlighem et al., 2016; Levermann et al., 2012; Bondzio et al., 2017) and applying the method onto other tidewater glaciers.

Characterization and Modeling of a Control Moment Gyroscope

DTIC Science & Technology

2015-03-26

parallel, and angular directions [16]. The rotor is powered by a brushless DC motor rated to 557.9 mN-m (4.938 in-lbf) [4]. The motor has Hall effect ...mass balance installed on rotor housing Gimbal Balancing Test Procedures. To evaluate the effectiveness of the mass balance, the gimbal was tested...in which the rotor is running The vehicle-level model test (Section 4.9) predicts the effects of CMG gear lash on overall vehicle performance. Gear

Influence of Persistent Wind Scour on the Surface Mass Balance of Antarctica

NASA Technical Reports Server (NTRS)

Das, Indrani; Bell, Robin E.; Scambos, Ted A.; Wolovick, Michael; Creyts, Timothy T.; Studinger, Michael; Fearson, Nicholas; Nicolas, Julien P.; Lenaerts, Jan T. M.; vandenBroeke, Michiel R.

2013-01-01

Accurate quantification of surface snow accumulation over Antarctica is a key constraint for estimates of the Antarctic mass balance, as well as climatic interpretations of ice-core records. Over Antarctica, near-surface winds accelerate down relatively steep surface slopes, eroding and sublimating the snow. This wind scour results in numerous localized regions (< or = 200 sq km) with reduced surface accumulation. Estimates of Antarctic surface mass balance rely on sparse point measurements or coarse atmospheric models that do not capture these local processes, and overestimate the net mass input in wind-scour zones. Here we combine airborne radar observations of unconformable stratigraphic layers with lidar-derived surface roughness measurements to identify extensive wind-scour zones over Dome A, in the interior of East Antarctica. The scour zones are persistent because they are controlled by bedrock topography. On the basis of our Dome A observations, we develop an empirical model to predict wind-scour zones across the Antarctic continent and find that these zones are predominantly located in East Antarctica. We estimate that approx. 2.7-6.6% of the surface area of Antarctica has persistent negative net accumulation due to wind scour, which suggests that, across the continent, the snow mass input is overestimated by 11-36.5 Gt /yr in present surface-mass-balance calculations.

Research concerning the balancing of a plane mechanism

NASA Astrophysics Data System (ADS)

Bădoiu, D.; Petrescu, M. G.; Antonescu, N. N.; Toma, G.

2018-01-01

By statically balancing of the plane mechanisms and especially those functioning at high speeds is being pursued the decrease of the value of the resultant force of all inertia forces that work on the component elements, thus obtaining a significant decrease in vibrations and shocks during the functioning. On the other hand, the existence of balancing masses which ensure the balancing of the mechanism leads to increased gauge and its mass. In this paper are presented some possibilities of statically balancing a plane mechanism which is composed of three independent contours. First is analyzed the case when the mechanism is totally balanced. Then a solution is proposed for a partial balancing of the mechanism based on the balancing of the first harmonic of the inertia force developed in a piston of the mechanism. Finally, are presented some simulation results concerning the variation of the value of the resultant inertia force during a cinematic cycle when the mechanism is unbalanced and when it is partially balanced. Also, it is analyzed the variation of the motor moment when the mechanism is unbalanced and when is totally and partially balanced.

Surface mass balance contributions to acceleration of Antarctic ice mass loss during 2003-2013

NASA Astrophysics Data System (ADS)

Seo, Ki-Weon; Wilson, Clark R.; Scambos, Ted; Kim, Baek-Min; Waliser, Duane E.; Tian, Baijun; Kim, Byeong-Hoon; Eom, Jooyoung

2015-05-01

Recent observations from satellite gravimetry (the Gravity Recovery and Climate Experiment (GRACE) mission) suggest an acceleration of ice mass loss from the Antarctic Ice Sheet (AIS). The contribution of surface mass balance changes (due to variable precipitation) is compared with GRACE-derived mass loss acceleration by assessing the estimated contribution of snow mass from meteorological reanalysis data. We find that over much of the continent, the acceleration can be explained by precipitation anomalies. However, on the Antarctic Peninsula and other parts of West Antarctica, mass changes are not explained by precipitation and are likely associated with ice discharge rate increases. The total apparent GRACE acceleration over all of the AIS between 2003 and 2013 is -13.6 ± 7.2 Gt/yr2. Of this total, we find that the surface mass balance component is -8.2 ± 2.0 Gt/yr2. However, the GRACE estimate appears to contain errors arising from the atmospheric pressure fields used to remove air mass effects. The estimated acceleration error from this effect is about 9.8 ± 5.8 Gt/yr2. Correcting for this yields an ice discharge acceleration of -15.1 ± 6.5 Gt/yr2.

Surface Mass Balance Contributions to Acceleration of Antarctic Ice Mass Loss during 2003- 2013

NASA Astrophysics Data System (ADS)

Seo, K. W.; Wilson, C. R.; Scambos, T. A.; Kim, B. M.; Waliser, D. E.; Tian, B.; Kim, B.; Eom, J.

2015-12-01

Recent observations from satellite gravimetry (the GRACE mission) suggest an acceleration of ice mass loss from the Antarctic Ice Sheet (AIS). The contribution of surface mass balance changes (due to variable precipitation) is compared with GRACE-derived mass loss acceleration by assessing the estimated contribution of snow mass from meteorological reanalysis data. We find that over much of the continent, the acceleration can be explained by precipitation anomalies. However, on the Antarctic Peninsula and other parts of West Antarctica mass changes are not explained by precipitation and are likely associated with ice discharge rate increases. The total apparent GRACE acceleration over all of the AIS between 2003 and 2013 is -13.6±7.2 GTon/yr2. Of this total, we find that the surface mass balance component is -8.2±2.0 GTon/yr2. However, the GRACE estimate appears to contain errors arising from the atmospheric pressure fields used to remove air mass effects. The estimated acceleration error from this effect is about 9.8±5.8 GTon/yr2. Correcting for this yields an ice discharge acceleration of -15.1±6.5 GTon/yr2.

Independent effects of adding weight and inertia on balance during quiet standing.

PubMed

Costello, Kerry Elizabeth; Matrangola, Sara Louise; Madigan, Michael Lawrence

2012-04-16

Human balance during quiet standing is influenced by adding mass to the body with a backpack, with symmetrically-applied loads to the trunk, or with obesity. Adding mass to the body increases both the weight and inertia of the body, which theoretically could provide counteracting effects on body dynamics and balance. Understanding the independent effects of adding weight and inertia on balance may provide additional insight into human balance that could lead to novel advancements in balance training and rehabilitation. Therefore, the purpose of this study was to investigate the independent effects of adding weight and inertia on balance during quiet standing. Sixteen normal-weight young adult participants stood as still as possible on a custom-built backboard apparatus under four experimental conditions: baseline, added inertia only, added weight only, and added inertia and weight. Adding inertia by itself had no measurable effect on center of pressure movement or backboard movement. Adding weight by itself increased center of pressure movement (indicated greater effort by the postural control system to stand as still as possible) and backboard movement (indicating a poorer ability of the body to stand as still as possible). Adding inertia and weight at the same time increased center of pressure movement but did not increase backboard movement compared to the baseline condition. Adding inertia and adding weight had different effects on balance. Adding inertia by itself had no effect on balance. Adding weight by itself had a negative effect on balance. When adding inertia and weight at the same time, the added inertia appeared to lessen (but did not eliminate) the negative effect of adding weight on balance. These results improve our fundamental understanding of how added mass influences human balance.

Assessment and Optimization of the Accuracy of an Aircraft-Based Technique Used to Quantify Greenhouse Gas Emission Rates from Point Sources

NASA Astrophysics Data System (ADS)

Shepson, P. B.; Lavoie, T. N.; Kerlo, A. E.; Stirm, B. H.

2016-12-01

Understanding the contribution of anthropogenic activities to atmospheric greenhouse gas concentrations requires an accurate characterization of emission sources. Previously, we have reported the use of a novel aircraft-based mass balance measurement technique to quantify greenhouse gas emission rates from point and area sources, however, the accuracy of this approach has not been evaluated to date. Here, an assessment of method accuracy and precision was performed by conducting a series of six aircraft-based mass balance experiments at a power plant in southern Indiana and comparing the calculated CO2 emission rates to the reported hourly emission measurements made by continuous emissions monitoring systems (CEMS) installed directly in the exhaust stacks at the facility. For all flights, CO2 emissions were quantified before CEMS data were released online to ensure unbiased analysis. Additionally, we assess the uncertainties introduced to the final emission rate caused by our analysis method, which employs a statistical kriging model to interpolate and extrapolate the CO2 fluxes across the flight transects from the ground to the top of the boundary layer. Subsequently, using the results from these flights combined with the known emissions reported by the CEMS, we perform an inter-model comparison of alternative kriging methods to evaluate the performance of the kriging approach.

At-line process analytical technology (PAT) for more efficient scale up of biopharmaceutical microfiltration unit operations.

PubMed

Watson, Douglas S; Kerchner, Kristi R; Gant, Sean S; Pedersen, Joseph W; Hamburger, James B; Ortigosa, Allison D; Potgieter, Thomas I

2016-01-01

Tangential flow microfiltration (MF) is a cost-effective and robust bioprocess separation technique, but successful full scale implementation is hindered by the empirical, trial-and-error nature of scale-up. We present an integrated approach leveraging at-line process analytical technology (PAT) and mass balance based modeling to de-risk MF scale-up. Chromatography-based PAT was employed to improve the consistency of an MF step that had been a bottleneck in the process used to manufacture a therapeutic protein. A 10-min reverse phase ultra high performance liquid chromatography (RP-UPLC) assay was developed to provide at-line monitoring of protein concentration. The method was successfully validated and method performance was comparable to previously validated methods. The PAT tool revealed areas of divergence from a mass balance-based model, highlighting specific opportunities for process improvement. Adjustment of appropriate process controls led to improved operability and significantly increased yield, providing a successful example of PAT deployment in the downstream purification of a therapeutic protein. The general approach presented here should be broadly applicable to reduce risk during scale-up of filtration processes and should be suitable for feed-forward and feed-back process control. © 2015 American Institute of Chemical Engineers.

California's Snow Gun and its implications for mass balance predictions under greenhouse warming

NASA Astrophysics Data System (ADS)

Howat, I.; Snyder, M.; Tulaczyk, S.; Sloan, L.

2003-12-01

Precipitation has received limited treatment in glacier and snowpack mass balance models, largely due to the poor resolution and confidence of precipitation predictions relative to temperature predictions derived from atmospheric models. Most snow and glacier mass balance models rely on statistical or lapse rate-based downscaling of general or regional circulation models (GCM's and RCM's), essentially decoupling sub-grid scale, orographically-driven evolution of atmospheric heat and moisture. Such models invariably predict large losses in the snow and ice volume under greenhouse warming. However, positive trends in the mass balance of glaciers in some warming maritime climates, as well as at high elevations of the Greenland Ice Sheet, suggest that increased precipitation may play an important role in snow- and glacier-climate interactions. Here, we present a half century of April snowpack data from the Sierra Nevada and Cascade mountains of California, USA. This high-density network of snow-course data indicates that a gain in winter snow accumulation at higher elevations has compensated loss in snow volume at lower elevations by over 50% and has led to glacier expansion on Mt. Shasta. These trends are concurrent with a region-wide increase in winter temperatures up to 2° C. They result from the orographic lifting and saturation of warmer, more humid air leading to increased precipitation at higher elevations. Previous studies have invoked such a "Snow Gun" effect to explain contemporaneous records of Tertiary ocean warming and rapid glacial expansion. A climatological context of the California's "snow gun" effect is elucidated by correlation between the elevation distribution of April SWE observations and the phase of the Pacific Decadal Oscillation and the El Nino Southern Oscillation, both controlling the heat and moisture delivered to the U.S. Pacific coast. The existence of a significant "Snow Gun" effect presents two challenges to snow and glacier mass balance modeling. Firstly, the link between amplification of orographic precipitation and the temporal evolution of ocean-climate oscillations indicates that prediction of future mass balance trends requires consideration of the timing and amplitude of such oscillations. Only recently have ocean-atmosphere models begun to realistically produce such temporal variability. Secondly, the steepening snow mass-balance elevation-gradient associated with the "Snow Gun" implies greater spatial variability in balance with warming. In a warming climate, orographic processes at a scale finer that the highest resolution RCM (>20km grid) become increasingly important and predictions based on lower elevations become increasingly inaccurate for higher elevations. Therefore, thermodynamic interaction between atmospheric heat, moisture and topography must be included in downscaling techniques. In order to demonstrate the importance of the thermodynamic downscaling in mass balance predictions, we nest a high-resolution (100m grid), coupled Orographic Precipitation and Surface Energy balance Model (OPSEM) into the RegC2.5 RCM (40 km grid) and compare results. We apply this nesting technique to Mt. Shasta, California, an area of high topography (~4000m) relative to its RegCM2.5 grid elevation (1289m). These models compute average April snow volume under present and doubled-present Atmospheric CO2 concentrations. While the RegCM2.5 regional model predicts an 83% decrease in April SWE, OPSEM predicts a 16% increase. These results indicate that thermodynamic interactions between the atmosphere and topography at sub- RCM grid resolution must be considered in mass balance models.

A genetic algorithm approach to estimate glacier mass variations from GRACE data

NASA Astrophysics Data System (ADS)

Reimond, Stefan; Klinger, Beate; Krauss, Sandro; Mayer-Gürr, Torsten

2017-04-01

The application of a genetic algorithm (GA) to the inference of glacier mass variations with a point-mass modeling method is described. GRACE K-band ranging data (available since April 2002) processed at the Graz University of Technology serve as input for this study. The reformulation of the point-mass inversion method in terms of an optimization problem is motivated by two reasons: first, an improved choice of the positions of the modeled point-masses (with a particular focus on the depth parameter) is expected to increase the signal-to-noise ratio. Considering these coordinates as additional unknown parameters (besides from the mass change magnitudes) results in a highly non-linear optimization problem. The second reason is that the mass inversion from satellite tracking data is an ill-posed problem, and hence regularization becomes necessary. The main task in this context is the determination of the regularization parameter, which is typically done by means of heuristic selection rules like, e.g., the L-curve criterion. In this study, however, the challenge of selecting a suitable balancing parameter (or even a matrix) is tackled by introducing regularization to the overall optimization problem. Based on this novel approach, estimations of ice-mass changes in various alpine glacier systems (e.g. Svalbard) are presented and compared to existing results and alternative inversion methods.

40 CFR 1065.307 - Linearity verification.

Code of Federal Regulations, 2010 CFR

2010-07-01

... different flow rates. Use a gravimetric reference measurement (such as a scale, balance, or mass comparator... the gas-division system to divide the span gas with purified air or nitrogen. Select gas divisions... PM balance, m max refers to the typical mass of a PM filter. (ii) For linearity verification of...

MODELLING SEDIMENT TRANSPORT FOR THE LAKE MICHIGAN MASS BALANCE PROJECT

EPA Science Inventory

A sediment transport model is one component of the overall ensemble of models being developed for the Lake Michigan Mass Balance. The SEDZL model is being applied to simulate the fine-grained sediment transport in Lake Michigan for the 1982-1983 and 1994-1995 periods. Model perf...

AN OVERVIEW OF THE LAKE MICHIGAN MASS BALANCE MODELING PROJECT: BACKGROUND, ACCOMPLISHMENTS, AND FUTURE WORK

EPA Science Inventory

Modeling associated with the Lake Michigan Mass Balance Project (LMMBP) is being conducted using WASP-type water quality models to gain a better understanding of the ecosystem transport and fate of polychlorinated biphenyls (PCBs), atrazine, mercury, and trans-nonachlor in Lake M...

POLLUTION BALANCE: A NEW METHODOLOGY FOR MINIMIZING WASTE PRODUCTION IN MANUFACTURING PROCESSES.

EPA Science Inventory

A new methodolgy based on a generic pollution balance equation, has been developed for minimizing waste production in manufacturing processes. A "pollution index," defined as the mass of waste produced per unit mass of a product, has been introduced to provide a quantitative meas...

40 CFR 98.246 - Data reporting requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... values are not to be used in the mass balance calculation. (11) If you determine carbon content or... use the mass balance methodology in § 98.243(c), you must report the information specified in... of petrochemical produced, names of other products, and names of carbon-containing feedstocks. (3...

40 CFR 98.246 - Data reporting requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... values are not to be used in the mass balance calculation. (11) If you determine carbon content or... use the mass balance methodology in § 98.243(c), you must report the information specified in... of petrochemical produced, names of other products, and names of carbon-containing feedstocks. (3...

40 CFR 98.246 - Data reporting requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... values are not to be used in the mass balance calculation. (11) If you determine carbon content or... use the mass balance methodology in § 98.243(c), you must report the information specified in... of petrochemical produced, names of other products, and names of carbon-containing feedstocks. (3...

MICHTOX: A MASS BALANCE AND BIOACCUMULATION MODEL FOR TOXIC CHEMICALS IN LAKE MICHIGAN

EPA Science Inventory

MICHTOX is a toxic chemical mass balance and bioaccumulation model for Lake Michigan. It was developed for USEPA's Region V in support of the Lake Michigan Lake-wide Management Plan (LaMP) to provide guidance on expected water quality improvements in response to critical pollutan...

MASS BALANCE MODELLING OF PCBS IN THE FOX RIVER/GREEN BAY COMPLEX

EPA Science Inventory

The USEPA Office of Research and Development developed and applies a multimedia, mass balance modeling approach to the Fox River/Green Bay complex to aid managers with remedial decision-making. The suite of models were applied to PCBs due to the long history of contamination and ...

Using Bayesian methods to predict climate impacts on groundwater availability and agricultural production in Punjab, India

NASA Astrophysics Data System (ADS)

Russo, T. A.; Devineni, N.; Lall, U.

2015-12-01

Lasting success of the Green Revolution in Punjab, India relies on continued availability of local water resources. Supplying primarily rice and wheat for the rest of India, Punjab supports crop irrigation with a canal system and groundwater, which is vastly over-exploited. The detailed data required to physically model future impacts on water supplies agricultural production is not readily available for this region, therefore we use Bayesian methods to estimate hydrologic properties and irrigation requirements for an under-constrained mass balance model. Using measured values of historical precipitation, total canal water delivery, crop yield, and water table elevation, we present a method using a Markov chain Monte Carlo (MCMC) algorithm to solve for a distribution of values for each unknown parameter in a conceptual mass balance model. Due to heterogeneity across the state, and the resolution of input data, we estimate model parameters at the district-scale using spatial pooling. The resulting model is used to predict the impact of precipitation change scenarios on groundwater availability under multiple cropping options. Predicted groundwater declines vary across the state, suggesting that crop selection and water management strategies should be determined at a local scale. This computational method can be applied in data-scarce regions across the world, where water resource management is required to resolve competition between food security and available resources in a changing climate.

Mountain Glaciers and Ice Caps

USGS Publications Warehouse

Ananichheva, Maria; Arendt, Anthony; Hagen, Jon-Ove; Hock, Regine; Josberger, Edward G.; Moore, R. Dan; Pfeffer, William Tad; Wolken, Gabriel J.

2011-01-01

Projections of future rates of mass loss from mountain glaciers and ice caps in the Arctic focus primarily on projections of changes in the surface mass balance. Current models are not yet capable of making realistic forecasts of changes in losses by calving. Surface mass balance models are forced with downscaled output from climate models driven by forcing scenarios that make assumptions about the future rate of growth of atmospheric greenhouse gas concentrations. Thus, mass loss projections vary considerably, depending on the forcing scenario used and the climate model from which climate projections are derived. A new study in which a surface mass balance model is driven by output from ten general circulation models (GCMs) forced by the IPCC (Intergovernmental Panel on Climate Change) A1B emissions scenario yields estimates of total mass loss of between 51 and 136 mm sea-level equivalent (SLE) (or 13% to 36% of current glacier volume) by 2100. This implies that there will still be substantial glacier mass in the Arctic in 2100 and that Arctic mountain glaciers and ice caps will continue to influence global sea-level change well into the 22nd century.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghosh, Debojyoti; Constantinescu, Emil M.

The numerical simulation of meso-, convective-, and microscale atmospheric flows requires the solution of the Euler or the Navier-Stokes equations. Nonhydrostatic weather prediction algorithms often solve the equations in terms of derived quantities such as Exner pressure and potential temperature (and are thus not conservative) and/or as perturbations to the hydrostatically balanced equilibrium state. This paper presents a well-balanced, conservative finite difference formulation for the Euler equations with a gravitational source term, where the governing equations are solved as conservation laws for mass, momentum, and energy. Preservation of the hydrostatic balance to machine precision by the discretized equations is essentialmore » because atmospheric phenomena are often small perturbations to this balance. The proposed algorithm uses the weighted essentially nonoscillatory and compact-reconstruction weighted essentially nonoscillatory schemes for spatial discretization that yields high-order accurate solutions for smooth flows and is essentially nonoscillatory across strong gradients; however, the well-balanced formulation may be used with other conservative finite difference methods. The performance of the algorithm is demonstrated on test problems as well as benchmark atmospheric flow problems, and the results are verified with those in the literature.« less

Construction of a new watt balance with the goal to realize the kilogram in the US

NASA Astrophysics Data System (ADS)

Schlamminger, Stephan; Haddad, Darine; Seifert, Frank; Chao, Leon; Newell, David; Pratt, Jon

2015-04-01

A watt balance is a mechanical device that compares mechanical power to electrical power. Since electrical power is measured using quantum physics by employing the Josephson effect and the Quantum Hall effect, electrical power can be measured as a product of a known factor, two frequencies, and the Planck constant h. Mechanical power is given by mgv , where m is the mass of a weight, g the local acceleration, and v the velocity. Hence, the watt balance provides a link between mass and Planck's constant. Currently several watt balances worldwide are employed to measure h. A redefinition of the international system of units (SI) is currently in discussion and may become reality as early as 2018. In the new SI, the numerical value of the Planck constant will be fixed and the watt balance is a means to realize the unit of mass. Researchers at NIST are preparing for a new SI and we have started in 2011 with plans to design a new watt balance capable of realizing the kilogram with relative uncertainties of a few parts in 108. Construction of the new watt balance has started in 2014. In my talk, I will show some of the latest results achieved with this apparatus.

Leak rate measurements for satellite subsystems and residual gas analysis during space environment tests. [thermal vacuum and solar simulation tests

NASA Technical Reports Server (NTRS)

Nuss, H. E.

1975-01-01

The measuring and evaluation procedure for the determination of leak rates of satellite subsystems with a quadrupole mass spectrometer, and the results of the residual gas analysis are described. The method selected for leak rate determination was placing the system into a vacuum chamber and furnishing the chamber with a mass spectrometer and calibrated leaks. The residual gas of a thermal vacuum test facility, in which the thermal balance test radiation input was simulated by a heated canister, was analyzed with the mass spectrometer in the atomic mass unit range up to 300 amu. In addition to the measurements during the space environment tests, mass spectrometric studies were performed with samples of spacecraft materials. The studies were carried out during tests for the projects HELIOS, AEROS B and SYMPHONIE.

Development of a mass balance model for estimating PCB export from the lower Fox River to Green Bay

DOE Office of Scientific and Technical Information (OSTI.GOV)

Velleux, M.; Endicott, D.

A mass balance approach was used to model contaminant cycling in the lower Fox River from the DePere Dam to Green Bay. The objectives of this research were (1) to estimate present contaminant export from the Fox River to Green Bay, and (2) to quantify contaminant transport and fate pathways in the lower river for the study period. Specifically, a model describing the transport, fate, and export of chlorides, total suspended solids, total PCBs, and six PCB congeners for the lower Fox River was developed. Field data collected as part of the U.S. Environmental Protection Agency's Green Bay Mass Balancemore » Study were used to calibrate the model. Model results suggest that the transport of inplace pollutants significantly contributed to the cumulative export of total PCBs over this period. Estimated total PCB transport in the Fox River during 1989 increased 60% between the dam and river mouth due to the resuspension of lower river sediments. Total suspended solids and PCB predictions are most sensitive to particle transport parameters, particularly the settling and resuspension velocities. The significant components of the total PCB mass balance are import (loading over the DePere Dam), settling, resuspension, and export to Green Bay. Volatilization, porewater transport, and point source input were not significant to the mass balance. Present point source discharges to the river are not significant total PCB sources, collectively contributing less than 6 kg of PCB to the river during the mass balance period.« less

Methods of analysis for complex organic aerosol mixtures from urban emission sources of particulate carbon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mazurek, M.A.; Hildemann, L.M.; Cass, G.R.

1990-04-01

Extractable organic compounds having between 6 to 40 carbon atoms comprise an important mass fraction of the fine particulate matter samples from major urban emission sources. Depending on the emission source type, this solvent-soluble fraction accounts for <20% to 100% of the total organic aerosol mass, as measured by quantitative high-resolution has chromatography (HRGC) with flame ionization detection. In addition to total extract quantitation, HRGC can be applied to further analyses of the mass distributions of elutable organics present in the complex aerosol extract mixtures, thus generating profiles that serve as fingerprints'' for the sources of interest. This HRGC analyticalmore » method is applied to emission source samples that contain between 7 to 12,000 {mu}g/filter organic carbon. It is shown to be a sensitive technique for analysis of carbonaceous aerosol extract mixtures having diverse mass loadings and species distributions. This study describes the analytical chemical methods that have been applied to: the construction of chemical mass balances based on the mass of fine organic aerosol emitted for major urban sources of particulate carbon; and the generation of discrete emission source chemical profiles derived from chromatographic characteristics of the organic aerosol components. 21 refs., 1 fig., 2 tabs.« less

Passive shimming of a superconducting magnet using the L1-norm regularized least square algorithm.

PubMed

Kong, Xia; Zhu, Minhua; Xia, Ling; Wang, Qiuliang; Li, Yi; Zhu, Xuchen; Liu, Feng; Crozier, Stuart

2016-02-01

The uniformity of the static magnetic field B0 is of prime importance for an MRI system. The passive shimming technique is usually applied to improve the uniformity of the static field by optimizing the layout of a series of steel shims. The steel pieces are fixed in the drawers in the inner bore of the superconducting magnet, and produce a magnetizing field in the imaging region to compensate for the inhomogeneity of the B0 field. In practice, the total mass of steel used for shimming should be minimized, in addition to the field uniformity requirement. This is because the presence of steel shims may introduce a thermal stability problem. The passive shimming procedure is typically realized using the linear programming (LP) method. The LP approach however, is generally slow and also has difficulty balancing the field quality and the total amount of steel for shimming. In this paper, we have developed a new algorithm that is better able to balance the dual constraints of field uniformity and the total mass of the shims. The least square method is used to minimize the magnetic field inhomogeneity over the imaging surface with the total mass of steel being controlled by an L1-norm based constraint. The proposed algorithm has been tested with practical field data, and the results show that, with similar computational cost and mass of shim material, the new algorithm achieves superior field uniformity (43% better for the test case) compared with the conventional linear programming approach. Copyright © 2016 Elsevier Inc. All rights reserved.

A Simple, Low-cost, and Robust System to Measure the Volume of Hydrogen Evolved by Chemical Reactions with Aqueous Solutions

PubMed Central

Brack, Paul; Dann, Sandie; Wijayantha, K. G. Upul; Adcock, Paul; Foster, Simon

2016-01-01

There is a growing research interest in the development of portable systems which can deliver hydrogen on-demand to proton exchange membrane (PEM) hydrogen fuel cells. Researchers seeking to develop such systems require a method of measuring the generated hydrogen. Herein, we describe a simple, low-cost, and robust method to measure the hydrogen generated from the reaction of solids with aqueous solutions. The reactions are conducted in a conventional one-necked round-bottomed flask placed in a temperature controlled water bath. The hydrogen generated from the reaction in the flask is channeled through tubing into a water-filled inverted measuring cylinder. The water displaced from the measuring cylinder by the incoming gas is diverted into a beaker on a balance. The balance is connected to a computer, and the change in the mass reading of the balance over time is recorded using data collection and spreadsheet software programs. The data can then be approximately corrected for water vapor using the method described herein, and parameters such as the total hydrogen yield, the hydrogen generation rate, and the induction period can also be deduced. The size of the measuring cylinder and the resolution of the balance can be changed to adapt the setup to different hydrogen volumes and flow rates. PMID:27584581

Estimating Regional Mass Balance of Himalayan Glaciers Using Hexagon Imagery: An Automated Approach

NASA Astrophysics Data System (ADS)

Maurer, J. M.; Rupper, S.

2013-12-01

Currently there is much uncertainty regarding the present and future state of Himalayan glaciers, which supply meltwater for river systems vital to more than 1.4 billion people living throughout Asia. Previous assessments of regional glacier mass balance in the Himalayas using various remote sensing and field-based methods give inconsistent results, and most assessments are over relatively short (e.g., single decade) timescales. This study aims to quantify multi-decadal changes in volume and extent of Himalayan glaciers through efficient use of the large database of declassified 1970-80s era Hexagon stereo imagery. Automation of the DEM extraction process provides an effective workflow for many images to be processed and glacier elevation changes quantified with minimal user input. The tedious procedure of manual ground control point selection necessary for block-bundle adjustment (as ephemeral data is not available for the declassified images) is automated using the Maximally Stable Extremal Regions algorithm, which matches image elements between raw Hexagon images and georeferenced Landsat 15 meter panchromatic images. Additional automated Hexagon DEM processing, co-registration, and bias correction allow for direct comparison with modern ASTER and SRTM elevation data, thus quantifying glacier elevation and area changes over several decades across largely inaccessible mountainous regions. As consistent methodology is used for all glaciers, results will likely reveal significant spatial and temporal patterns in regional ice mass balance. Ultimately, these findings could have important implications for future water resource management in light of environmental change.

The physical basis of glacier volume-area scaling

USGS Publications Warehouse

Bahr, D.B.; Meier, M.F.; Peckham, S.D.

1997-01-01

Ice volumes are known for only a few of the roughly 160,000 glaciers worldwide but are important components of many climate and sea level studies which require water flux estimates. A scaling analysis of the mass and momentum conservation equations shows that glacier volumes can be related by a power law to more easily observed glacier surface areas. The relationship requires four closure choices for the scaling behavior of glacier widths, slopes, side drag and mass balance. Reasonable closures predict a volume-area scaling exponent which is consistent with observations, giving a physical and practical basis for estimating ice volumes. Glacier volume is insensitive to perturbations in the mass balance scaling, but changes in average accumulation area ratios reflect significant changes in the scaling of both mass balance and ice volume. Copyright 1997 by the American Geophysical Union.

Use of the Microsoft Kinect system to characterize balance ability during balance training.

PubMed

Lim, Dohyung; Kim, ChoongYeon; Jung, HoHyun; Jung, Dukyoung; Chun, Keyoung Jin

2015-01-01

The risk of falling increases significantly in the elderly because of deterioration of the neural musculature regulatory mechanisms. Several studies have investigated methods of preventing falling using real-time systems to evaluate balance; however, it is difficult to monitor the results of such characterizations in real time. Herein, we describe the use of Microsoft's Kinect depth sensor system to evaluate balance in real time. Six healthy male adults (25.5±1.8 years, 173.9±6.4 cm, 71.4±6.5 kg, and 23.6±2.4 kg/m(2)), with normal balance abilities and with no musculoskeletal disorders, were selected to participate in the experiment. Movements of the participants were induced by controlling the base plane of the balance training equipment in various directions. The dynamic motion of the subjects was measured using two Kinect depth sensor systems and a three-dimensional motion capture system with eight infrared cameras. The two systems yielded similar results for changes in the center of body mass (P>0.05) with a large Pearson's correlation coefficient of γ>0.60. The results for the two systems showed similarity in the mean lower-limb joint angle with flexion-extension movements, and these values were highly correlated (hip joint: within approximately 4.6°; knee joint: within approximately 8.4°) (0.40<γ<0.74) (P>0.05). Large differences with a low correlation were, however, observed for the lower-limb joint angle in relation to abduction-adduction and internal-external rotation motion (γ<0.40) (P<0.05). These findings show that clinical and dynamic accuracy can be achieved using the Kinect system in balance training by measuring changes in the center of body mass and flexion-extension movements of the lower limbs, but not abduction-adduction and internal-external rotation.

Black Carbon And Co-Pollutants Emissions And Energy Efficiency From Bricks Production In Guanajuato, Mexico

NASA Astrophysics Data System (ADS)

Molina, L. T.; Zavala, M.; Maiz, P.; Monsivais, I.; Chow, J.; Munguia, J.

2013-12-01

In many parts of the world, small-scale traditional brick kilns are a notorious informal sector source of urban air pollution. Many are both inefficient and burn highly polluting fuels that emit significant levels of black carbon and other pollutants into local communities and to the atmosphere, resulting in severe health and environmental impacts. It is estimated that there are nearly 20,000 traditional brick kilns in Mexico, in which bricks are still produced as they have been for centuries. They are made by hand, dried in the sun, and generally fired in small, one chamber kilns that use various types of fuels, including plastic refuse, used tires, manure, wood scrap, and used motor oil. Three brick kilns, two traditional kilns and an improved kiln (MK2), were sampled as part of the SLCFs-Mexico campaign in Guanajuato, Mexico during March of 2013. The concept of the MK-2 involves covering the kiln with a dome and channeling the output of an active kiln through a second, identical loaded kiln for its additional filtration of the effluents. The results of energy efficiency and carbon mass balance calculations are presented for comparing the production efficiency and carbon emissions from the sampled kilns. Measurements included PM2.5 mass with quartz filters and temporally-resolved elemental carbon and organic carbon composition obtained using thermo-optical methods. The carbon emissions obtained with the mass balance method are compared with concurrent, high- time resolution, emissions measurements obtained using the Aerodyne mobile laboratory employing the tracer method (see abstract by Fortner et al.)

Measurement of Dietary Restraint: Validity Tests of Four Questionnaires

PubMed Central

Williamson, Donald A.; Martin, Corby K.; York-Crowe, Emily; Anton, Stephen D.; Redman, Leanne M.; Han, Hongmei; Ravussin, Eric

2007-01-01

This study tested the validity of four measures of dietary restraint: Dutch Eating Behavior Questionnaire, Eating Inventory (EI), Revised Restraint Scale (RS), and the Current Dieting Questionnaire. Dietary restraint has been implicated as a determinant of overeating and binge eating. Conflicting findings have been attributed to different methods for measuring dietary restraint. The validity of four self-report measures of dietary restraint and dieting behavior was tested using: 1) factor analysis, 2) changes in dietary restraint in a randomized controlled trial of different methods to achieve calorie restriction, and 3) correlation of changes in dietary restraint with an objective measure of energy balance, calculated from the changes in fat mass and fat-free mass over a six-month dietary intervention. Scores from all four questionnaires, measured at baseline, formed a dietary restraint factor, but the RS also loaded on a binge eating factor. Based on change scores, the EI Restraint scale was the only measure that correlated significantly with energy balance expressed as a percentage of energy require d for weight maintenance. These findings suggest that that, of the four questionnaires tested, the EI Restraint scale was the most valid measure of the intent to diet and actual caloric restriction. PMID:17101191

Solubilizing properties of new surface-active agents, products of catalytic oxyethylation of cholic acid.

PubMed

Kołodziejczyk, Michał Krzysztof; Nachajski, Michal Jakub; Lukosek, Marek; Zgoda, Marian Mikołaj

2013-01-01

Solubilizing properties of aqueous solutions of a series of surface-active agents, products of oxyethylation of cholic acid, were examined in the present study. The content of oxyethylated segments determined by means of the 1H NMR method enabled the verification of the molecular mass of surfactants along with the calculation of the structural hydrophilic-lipophilic balance (HLB), the solubility parameter delta1/2, and the required solubility level of balance HLB(R). Viscosimetric measurements enabled the calculation of the limiting viscosity number, the content-average molecular mass, the effective volume, the hydrodynamic radius of the surfactant micelle and their equilibrium adducts with rutin, diclofenac and loratadine (BCS Class II and III). By means of the spectrophotometric method (UV) the amount of the solubilized diclofenac, loratadine and rutin (rutoside) was determined in the equilibrium system (saturated solution) in the environment of aqueous solutions of cholic acid derivatives of n(TE) = 20-70. The obtained results serve as a basis for determining the solubilization mechanism of lipophilic therapeutic products and indirectly for estimating the influence of the above process on pharmaceutical as well as biological availability of a micellar adduct from model drug forms (Lindbladt lithogenolitic index).

The BFMNU method as an alternative to the methods in use based on energy: study of the correlation between food energy and body mass.

PubMed

Rondini, Greta; Olearo, Beatrice; Soriano Del Castillo, José Miguel; Boselli, Pietro Marco

2018-03-01

to establish slimming guidelines and any other changing treatments is useful to know the individual's energy expenditure due to the fact that, nowadays, the incidence of many diseases related to the loss of lean mass and the accumulation of adipose tissue has increased. The dietary treatments are carried out on calculating the energy contained in food, and then put in relation to the total energy expended by the body in order to produce changes in body mass. the aim of this study was to evaluate the correlation between the food energy and body mass of different subjects in various pathophysiological conditions. one hundred and twenty subjects (male and female, aged 7-78 years old) were studied in various pathophysiological conditions and previously treated with the BFMNU (Biologia e Fisiologia Modellistica della Nutrizione Umana)method. a correlation coefficient R2 of 0.1256 was found between food energy of the diet usually followed by the subjects and their body mass. The correlation between food energy and food mass was with R2 of 0.211. The correlation between Δ% of food energy and Δ% of body mass of the subjects, obtained through dietary treatment with the BFMNU method, was 95.77 percent. the correlation between food energy and body mass is not significant, being a critical point about the diets designed on an energy basis. However, the body mass of an individual is determined by mass balance, regulated by corresponding metabolic rate, calculated by the BFMNU method, thanks to which the macronutrients in the diet are absorbed, redistributed and eliminated. A significant correlation, although not straight, is demonstrated between Δ% of food energy, supplied after processing through the dietary BFMNU method, and the Δ% of body mass, obtained following the dietetic path.

Estimating the Natural Flow Regime of Rivers With Long-Standing Development: The Northern Branch of the Rio Grande

NASA Astrophysics Data System (ADS)

Blythe, Todd L.; Schmidt, John C.

2018-02-01

An estimate of a river's natural flow regime is useful for water resource planning and ecosystem rehabilitation by providing insight into the predisturbance form and function of a river. The natural flow regime of most rivers has been perturbed by development during the 20th century and in some cases, before stream gaging began. The temporal resolution of natural flows estimated using traditional methods is typically not sufficient to evaluate cues that drive native ecosystem function. Additionally, these traditional methods are watershed specific and require large amounts of data to produce accurate results. We present a mass balance method that estimates natural flows at daily time step resolution for the northern branch of the Rio Grande, upstream from the Rio Conchos, that relies only on easily obtained streamflow data. Using an analytical change point method, we identified periods of the measured flow regime during the 20th century for comparison with the estimated natural flows. Our results highlight the significant deviation from natural conditions that occurred during the 20th century. The total annual flow of the northern branch is 95% lower than it would be in the absence of human use. The current 2 year flood has decreased by more than 60%, is shorter in duration, and peaks later in the year. When compared to unregulated flows estimated using traditional mass balance accounting methods, our approach provides similar results.

Tibetan Plateau glacier and hydrological change under stratospheric aerosol injection

NASA Astrophysics Data System (ADS)

Ji, D.

2017-12-01

As an important inland freshwater resource, mountain glaciers are highly related to human life, they provide water for many large rivers and play a very important role in regional water cycles. The response of mountain glaciers to future climate change is a topic of concern especially to the many people who rely on glacier-fed rivers for purposes such as irrigation. Geoengineering by stratospheric aerosol injection is a method of offsetting the global temperature rise from greenhouse gases. How the geoengineering by stratospheric aerosol injection affects the mass balance of mountain glaciers and adjacent river discharge is little understood. In this study, we use regional climate model WRF and catchment-based river model CaMa-Flood to study the impacts of stratospheric aerosol injection to Tibetan Plateau glacier mass balance and adjacent river discharge. To facilitate mountain glacier mass balance study, we improve the description of mountain glacier in the land surface scheme of WRF. The improvements include: (1) a fine mesh nested in WRF horizontal grid to match the highly non-uniform spatial distribution of the mountain glaciers, (2) revising the radiation flux at the glacier surface considering the surrounding terrain. We use the projections of five Earth system models for CMIP5 rcp45 and GeoMIP G4 scenarios to drive the WRF and CaMa-Flood models. The G4 scenario, which uses stratospheric aerosols to reduce the incoming shortwave while applying the rcp4.5 greenhouse gas forcing, starts stratospheric sulfate aerosol injection at a rate of 5 Tg per year over the period 2020-2069. The ensemble projections suggest relatively slower glacier mass loss rates and reduced river discharge at Tibetan Plateau and adjacent regions under geoengineering scenario by stratospheric aerosol injection.

Methods for measuring denitrification: Diverse approaches to a difficult problem

USGS Publications Warehouse

Groffman, Peter M; Altabet, Mary A.; Böhlke, J.K.; Butterbach-Bahl, Klaus; David, Mary B.; Firestone, Mary K.; Giblin, Anne E.; Kana, Todd M.; Nielsen , Lars Peter; Voytek, Mary A.

2006-01-01

Denitrification, the reduction of the nitrogen (N) oxides, nitrate (NO3−) and nitrite (NO2−), to the gases nitric oxide (NO), nitrous oxide (N2O), and dinitrogen (N2), is important to primary production, water quality, and the chemistry and physics of the atmosphere at ecosystem, landscape, regional, and global scales. Unfortunately, this process is very difficult to measure, and existing methods are problematic for different reasons in different places at different times. In this paper, we review the major approaches that have been taken to measure denitrification in terrestrial and aquatic environments and discuss the strengths, weaknesses, and future prospects for the different methods. Methodological approaches covered include (1) acetylene-based methods, (2) 15N tracers, (3) direct N2 quantification, (4) N2:Ar ratio quantification, (5) mass balance approaches, (6) stoichiometric approaches, (7) methods based on stable isotopes, (8) in situ gradients with atmospheric environmental tracers, and (9) molecular approaches. Our review makes it clear that the prospects for improved quantification of denitrification vary greatly in different environments and at different scales. While current methodology allows for the production of accurate estimates of denitrification at scales relevant to water and air quality and ecosystem fertility questions in some systems (e.g., aquatic sediments, well-defined aquifers), methodology for other systems, especially upland terrestrial areas, still needs development. Comparison of mass balance and stoichiometric approaches that constrain estimates of denitrification at large scales with point measurements (made using multiple methods), in multiple systems, is likely to propel more improvement in denitrification methods over the next few years.

Establishment of Class e1 Mass Standard of 50 kg

NASA Astrophysics Data System (ADS)

Yao, Hong; Wang, Jian; Ding, Jingan; Zhong, Ruilin; Ren, Xiaoping

Because of the equipment limit, the dissemination of large mass has been realized by a large amount of higher class of 20 kg weights since 1950s in China. But with improvement of the technique and customer's requirements, it is necessary to establish the mass standard of 50 kg weight. In 1990s, mass standard laboratory has set up Class E1 weight sets from 20 kg to 1 mg. To extend the mass capacity up to 50 kg of Class E1, it is not only to produce Class E1 50 kg weight and import a mass comparator, but also need to lift the heavy weight from weight box to balance receptor safely. Up to now, the mass comparator has been installed in Hepingli campus of NIM. Two pieces of Class E1 50 kg weights are determined by combination weighing method. A lifting device has been mounted close to the mass comparator in order to move the 50 kg easily.

LM-3: A High-resolution Lake Michigan Mass Balance Water Quality Model

EPA Science Inventory

This report is a user’s manual that describes the high-resolution mass balance model known as LM3. LM3 has been applied to Lake Michigan to describe the transport and fate of atrazine, PCB congeners, and chloride in that system. The model has also been used to model eutrophicat...

When Equal Masses Don't Balance

ERIC Educational Resources Information Center

Newburgh, Ronald; Peidle, Joseph; Rueckner, Wolfgang

2004-01-01

We treat a modified Atwood's machine in which equal masses do not balance because of being in an accelerated frame of reference. Analysis of the problem illuminates the meaning of inertial forces, d'Alembert's principle, the use of free-body diagrams and the selection of appropriate systems for the diagrams. In spite of the range of these…

Lake Michigan Mass Balance Study Post Audit: Integrated, Multi-media PCB Modeling and Forecasting for Lake Trout

EPA Science Inventory

The Lake Michigan (LM) Mass Balance Study was conducted to measure and model polychlorinated biphenyls (PCBs) and other anthropogenic substances to gain a better understanding of the transport, fate, and effects of these substances within the system and to aid managers in the env...

Lake Michigan Mass Balance Study Post Audit: Integrated, Multi-media PCB Modeling and Forecasting for Lake Trout, Presentation

EPA Science Inventory

The Lake Michigan (LM) Mass Balance Study was conducted to measure and model polychlorinated biphenyls (PCBs) and other anthropogenic substances to gain a better understanding of the transport, fate, and effects of these substances within the system and to aid managers in the env...

Children Balance Theories and Evidence in Exploration, Explanation, and Learning

ERIC Educational Resources Information Center

Bonawitz, Elizabeth Baraff; van Schijndel, Tessa J. P.; Friel, Daniel; Schulz, Laura

2012-01-01

We look at the effect of evidence and prior beliefs on exploration, explanation and learning. In Experiment 1, we tested children both with and without differential prior beliefs about balance relationships (Center Theorists, mean: 82 months; Mass Theorists, mean: 89 months; No Theory children, mean: 62 months). Center and Mass Theory children who…

Comparison of tropical and subtropical glacier surface energy balance in Africa and South America

NASA Astrophysics Data System (ADS)

Nicholson, L.; Prinz, R.; Kinnard, C.; Mölg, T.; Winkler, M.; Kaser, G.

2010-05-01

Tropical glaciers exist only at high altitude, and meteorological and surface energy balance studies of these glaciers can tell us much about the conditions and changes occurring in the mid troposphere. Understanding the surface energy balance and resultant mass balance regime of tropical glaciers is prerequisite to predicting glacier evolution, and future meltwater contributions to local hydrological resources, in response to future climate scenarios. Tropical glacier mass balance variability is strongly linked to precipitation and, via this, to multi-annual climate oscillations such as ENSO and IOZM, so it is useful to understand what role these differing regional influences play in comparison to the similarities imposed by the overarching tropical climate conditions and seasonality. New surface energy balance and mass balance data is available from Lewis glacier (Kenya, 0°09' S; 37°18' E), and here we use an energy and mass balance model to determine the surface energy flux characteristics at this site through a wet and dry season. Results are compared with those from Kersten glacier (Tanzania, 3°04' S; 37°21' E) to understand how conditions at these two glaciers compare and thus what coherent and contrasting climatic information glaciological records from these two sites can be expected to deliver. Meteorological data available from glacier stations on Antizana (Ecuador, 0°25' S; 78°09' W), Artesonraju (Peru, 8°28' S; 77°38' W) Zongo (Bolivia, 16°39' S; 67°47' W) and Guanaco (Chile, 29°20' S; 70°00' W) glaciers in South America offer the opportunity to examine how the surface fluxes and seasonal variability of the energy balance compares to those of the African glaciers. We include the extra-tropical Chilean example for comparison with the similarly high altitude, cold ice of Kersten glacier.

Asia High Mountain Glacier Mass Balance

NASA Astrophysics Data System (ADS)

Shum, C. K.; Su, X.; Shang, K.; Cogley, J. G.; Zhang, G.; Howat, I. M.; Braun, A.; Kuo, C. Y.

2015-12-01

The Asian High Mountain encompassing the Qinghai-Tibetan Plateau has the largest glaciated regions in the world outside of Greenland and Antarctica. The Tibetan Plateau is the source or headwater of many major river systems, which provide water resources to more than a billion people downstream. The impact of climate change on the Tibetan Plateau physical processes, including mountain glacier wastage, permafrost active layer thickening, the timing and the quantity of the perennial snowpack melt affecting upstream catchments, river runoffs, land-use, have significant effects on downstream water resources. Exact quantification of the Asian High Mountain glacier wastage or its mass balance on how much of the melt water contributes to early 21st century global sea-level rise, remain illusive or the published results are arguably controversial. The recent observed significant increase of freshwater storage within the Tibetan Plateaus remains a limitation to exactly quantify mountain glacier wastage. Here, we provide an updated estimate of Asia high mountain glacier mass balance using satellite geodetic observations during the last decade, accounting for the hydrologic and other processes, and validated against available in situ mass balance data.

Alginic acid cell entrapment: a novel method for measuring in vivo macrophage cholesterol homeostasis

PubMed Central

Sontag, Timothy J.; Chellan, Bijoy; Bhanvadia, Clarissa V.; Getz, Godfrey S.; Reardon, Catherine A.

2015-01-01

Macrophage conversion to atherosclerotic foam cells is partly due to the balance of uptake and efflux of cholesterol. Cholesterol efflux from cells by HDL and its apoproteins for subsequent hepatic elimination is known as reverse cholesterol transport. Numerous methods have been developed to measure in vivo macrophage cholesterol efflux. Most methods do not allow for macrophage recovery for analysis of changes in cellular cholesterol status. We describe a novel method for measuring cellular cholesterol balance using the in vivo entrapment of macrophages in alginate, which retains incorporated cells while being permeable to lipoproteins. Recipient mice were injected subcutaneously with CaCl2 forming a bubble into which a macrophage/alginate suspension was injected, entrapping the macrophages. Cells were recovered after 24 h. Cellular free and esterified cholesterol mass were determined enzymatically and normalized to cellular protein. Both normal and cholesterol loaded macrophages undergo measureable changes in cell cholesterol when injected into WT and apoA-I-, LDL-receptor-, or apoE-deficient mice. Cellular cholesterol balance is dependent on initial cellular cholesterol status, macrophage cholesterol transporter expression, and apolipoprotein deficiency. Alginate entrapment allows for the in vivo measurement of macrophage cholesterol homeostasis and is a novel platform for investigating the role of genetics and therapeutic interventions in atherogenesis. PMID:25465389

Glaciers and ice caps outside Greenland

USGS Publications Warehouse

Sharp, Marin; Wolken, G.; Burgess, D.; Cogley, J.G.; Copland, L.; Thomson, L.; Arendt, A.; Wouters, B.; Kohler, J.; Andreassen, L.M.; O'Neel, Shad; Pelto, M.

2015-01-01

Mountain glaciers and ice caps cover an area of over 400 000 km2 in the Arctic, and are a major influence on global sea level (Gardner et al. 2011, 2013; Jacob et al. 2012). They gain mass by snow accumulation and lose mass by meltwater runoff. Where they terminate in water (ocean or lake), they also lose mass by iceberg calving. The climatic mass balance (Bclim, the difference between annual snow accumulation and annual meltwater runoff) is a widely used index of how glaciers respond to climate variability and change. The total mass balance (ΔM) is defined as the difference between annual snow accumulation and annual mass losses (by iceberg calving plus runoff).

Do we need long term terrestrial glacier mass balance monitoring for the future?

NASA Astrophysics Data System (ADS)

Slupetzky, H.

2003-04-01

Beginning with the International Geophysical Year 1958 and followed by other initiatives for world wide glacier observations such as the International Hydrological Decade, a distinctive increase of glacier research such as mass balance measurements was initiated. Some of the long term observations are not interrupted since then. However, because of various problems more and more of the long term series had to be given up. Is it possible to fully switch to air- and spaceborne techniques for glacier monitoring? For the mass balance series (and others glaciological series) we have by far not reached the length of meteorological records. There is an increasing need of longlasting observations for modelling and validation of remote-sensing of snow and ice. On Stubacher Sonnblick Kees, a small slope glacier (1,5 km2), in the Eastern Alps, Hohe Tauern, Province of Salzburg, a mass balance program is carried out. The mass balance has been measured for 39 years, with some extrapolations back to 1959, providing a record of 44 years. The glacier lost 12 Mio.m3 from 1964 to 2002, but had a period of mass gain between 1965 and 1981 of 9,8 Mio m3; since 1982 20,5 Mio m3 were lost. On another small glacier in the same area, the Oedenwinkel Kees, the mass gain period and the reaction of the glacier has been surveyed annualy showing a "kinematic wave". Some comperative measurements have been done on the Cathedral Massif Glacier, B.C., Canada 1977 to 1979 and 1998 and by using data from Storglaciaeren, Sweden, to evaluate the AAR ratio to estimate the net mas balances. There are some substantial reasons to carry on with direct mass balance measurements and not to interrupt or even abandon long series. There has been a great effort to sustain long term series. There is a great demand for new international initiatives to ensure the continuation of the world wide terrestrial glacier monitoring net. On Stubacher Sonnblickkees, it can be expected that the glacier will disappear within the next 60 to 80 years due to the global warming. So, a very new aspect arises: If the area now covered by the glacier is deglaciated and the base topography is known accurately, then it will be very interesting to observe a potential reglaciation in the future. Future glaciologists will much appreciate to use all the previously gathered results and it will be exciting to compare the polarity of the dual processes of mass gain, reconstution and advance of a glacier and the mass loss, shrinking and receding of the glacier.

Antarctic and Greenland ice sheet mass balance products from satellite gravimetry

NASA Astrophysics Data System (ADS)

Horwath, Martin; Groh, Andreas; Horvath, Alexander; Forsberg, René; Meister, Rakia; Barletta, Valentina R.; Shepherd, Andrew

2017-04-01

Because of their important role in the Earth's climate system, ESA's Climate Change Initiative (CCI) has identified both the Antarctic Ice Sheet (AIS) and the Greenland Ice Sheet (GIS) as Essential Climate Variables (ECV). Since respondents of a user survey indicated that the ice sheet mass balance is one of the most important ECV data products needed to better understand climate change, the AIS_cci and the GIS_cci project provide Gravimetric Mass Balance (GMB) products based on satellite gravimetry data. The GMB products are derived from GRACE (Gravity Recovery and Climate Experiment) monthly solutions of release ITSG-Grace2016 produced at TU Graz. GMB basin products (i.e. time series of monthly mass changes for the entire ice sheets and selected drainage basins) and GMB gridded products (e.g. mass balance estimates with a formal resolution of about 50km, covering the entire ice sheets) are generated for the period from 2002 until present. The first GMB product was released in mid 2016. Here we present an extended and updated version of the ESA CCI GMB products, which are freely available through data portals hosted by the projects (https://data1.geo.tu-dresden.de/ais_gmb, http://products.esa-icesheets-cci.org/products/downloadlist/GMB). Since the initial product release, the applied processing strategies have been improved in order to further reduce GRACE errors and to enhance the separation of signals super-imposed to the ice mass changes. While a regional integration approach is used by the AIS_cci project, the GMB products of the GIS_cci project are derived using a point mass inversion. The differences between both approaches are investigated through the example of the GIS, where an alternative GMB product was generated using the regional integration approach implemented by the AIS_cci. Finally, we present the latest mass balance estimates for both ice sheets as well as their corresponding contributions to global sea level rise.

Improvement of 2,4-dinitrophenylhydrazine derivatization method for carbon isotope analysis of atmospheric acetone.

PubMed

Wen, Sheng; Yu, Yingxin; Guo, Songjun; Feng, Yanli; Sheng, Guoying; Wang, Xinming; Bi, Xinhui; Fu, Jiamo; Jia, Wanglu

2006-01-01

Through simulation experiments of atmospheric sampling, a method via 2,4-dinitrophenylhydrazine (DNPH) derivatization was developed to measure the carbon isotopic composition of atmospheric acetone. Using acetone and a DNPH reagent of known carbon isotopic compositions, the simulation experiments were performed to show that no carbon isotope fractionation occurred during the processes: the differences between the predicted and measured data of acetone-DNPH derivatives were all less than 0.5 per thousand. The results permitted the calculation of the carbon isotopic compositions of atmospheric acetone using a mass balance equation. In this method, the atmospheric acetone was collected by a DNPH-coated silica cartridge, washed out as acetone-DNPH derivatives, and then analyzed by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). Using this method, the first available delta13C data of atmospheric acetone are presented. Copyright 2006 John Wiley & Sons, Ltd.

Ice-sheet mass balance and climate change.

PubMed

Hanna, Edward; Navarro, Francisco J; Pattyn, Frank; Domingues, Catia M; Fettweis, Xavier; Ivins, Erik R; Nicholls, Robert J; Ritz, Catherine; Smith, Ben; Tulaczyk, Slawek; Whitehouse, Pippa L; Zwally, H Jay

2013-06-06

Since the 2007 Intergovernmental Panel on Climate Change Fourth Assessment Report, new observations of ice-sheet mass balance and improved computer simulations of ice-sheet response to continuing climate change have been published. Whereas Greenland is losing ice mass at an increasing pace, current Antarctic ice loss is likely to be less than some recently published estimates. It remains unclear whether East Antarctica has been gaining or losing ice mass over the past 20 years, and uncertainties in ice-mass change for West Antarctica and the Antarctic Peninsula remain large. We discuss the past six years of progress and examine the key problems that remain.

Approximate convective heating equations for hypersonic flows

NASA Technical Reports Server (NTRS)

Zoby, E. V.; Moss, J. N.; Sutton, K.

1979-01-01

Laminar and turbulent heating-rate equations appropriate for engineering predictions of the convective heating rates about blunt reentry spacecraft at hypersonic conditions are developed. The approximate methods are applicable to both nonreacting and reacting gas mixtures for either constant or variable-entropy edge conditions. A procedure which accounts for variable-entropy effects and is not based on mass balancing is presented. Results of the approximate heating methods are in good agreement with existing experimental results as well as boundary-layer and viscous-shock-layer solutions.

Surface Energy and Mass Balance Model for Greenland Ice Sheet and Future Projections

NASA Astrophysics Data System (ADS)

Liu, Xiaojian

The Greenland Ice Sheet contains nearly 3 million cubic kilometers of glacial ice. If the entire ice sheet completely melted, sea level would raise by nearly 7 meters. There is thus considerable interest in monitoring the mass balance of the Greenland Ice Sheet. Each year, the ice sheet gains ice from snowfall and loses ice through iceberg calving and surface melting. In this thesis, we develop, validate and apply a physics based numerical model to estimate current and future surface mass balance of the Greenland Ice Sheet. The numerical model consists of a coupled surface energy balance and englacial model that is simple enough that it can be used for long time scale model runs, but unlike previous empirical parameterizations, has a physical basis. The surface energy balance model predicts ice sheet surface temperature and melt production. The englacial model predicts the evolution of temperature and meltwater within the ice sheet. These two models can be combined with estimates of precipitation (snowfall) to estimate the mass balance over the Greenland Ice Sheet. We first compare model performance with in-situ observations to demonstrate that the model works well. We next evaluate how predictions are degraded when we statistically downscale global climate data. We find that a simple, nearest neighbor interpolation scheme with a lapse rate correction is able to adequately reproduce melt patterns on the Greenland Ice Sheet. These results are comparable to those obtained using empirical Positive Degree Day (PDD) methods. Having validated the model, we next drove the ice sheet model using the suite of atmospheric model runs available through the CMIP5 atmospheric model inter-comparison, which in turn built upon the RCP 8.5 (business as usual) scenarios. From this exercise we predict how much surface melt production will increase in the coming century. This results in 4-10 cm sea level equivalent, depending on the CMIP5 models. Finally, we try to bound melt water production from CMIP5 data with the model by assuming that the Greenland Ice Sheet is covered in black carbon (lowering the albedo) and perpetually covered by optically thick clouds (increasing long wave radiation). This upper bound roughly triples surface meltwater production, resulting in 30 cm of sea level rise by 2100. These model estimates, combined with prior research suggesting an additional 40-100 cm of sea level rise associated with dynamical discharge, suggest that the Greenland Ice Sheet is poised to contribute significantly to sea level rise in the coming century.

Surface mass balance contributions to acceleration of Antarctic ice mass loss during 2003-2013.

PubMed

Seo, Ki-Weon; Wilson, Clark R; Scambos, Ted; Kim, Baek-Min; Waliser, Duane E; Tian, Baijun; Kim, Byeong-Hoon; Eom, Jooyoung

2015-05-01

Recent observations from satellite gravimetry (the Gravity Recovery and Climate Experiment (GRACE) mission) suggest an acceleration of ice mass loss from the Antarctic Ice Sheet (AIS). The contribution of surface mass balance changes (due to variable precipitation) is compared with GRACE-derived mass loss acceleration by assessing the estimated contribution of snow mass from meteorological reanalysis data. We find that over much of the continent, the acceleration can be explained by precipitation anomalies. However, on the Antarctic Peninsula and other parts of West Antarctica, mass changes are not explained by precipitation and are likely associated with ice discharge rate increases. The total apparent GRACE acceleration over all of the AIS between 2003 and 2013 is -13.6 ± 7.2 Gt/yr 2 . Of this total, we find that the surface mass balance component is -8.2 ± 2.0 Gt/yr 2 . However, the GRACE estimate appears to contain errors arising from the atmospheric pressure fields used to remove air mass effects. The estimated acceleration error from this effect is about 9.8 ± 5.8 Gt/yr 2 . Correcting for this yields an ice discharge acceleration of -15.1 ± 6.5 Gt/yr 2 .

Development and evaluation of virtual refrigerant mass flow sensors for fault detection and diagnostics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Woohyun; Braun, J.

Refrigerant mass flow rate is an important measurement for monitoring equipment performance and enabling fault detection and diagnostics. However, a traditional mass flow meter is expensive to purchase and install. A virtual refrigerant mass flow sensor (VRMF) uses a mathematical model to estimate flow rate using low-cost measurements and can potentially be implemented at low cost. This study evaluates three VRMFs for estimating refrigerant mass flow rate. The first model uses a compressor map that relates refrigerant flow rate to measurements of inlet and outlet pressure, and inlet temperature measurements. The second model uses an energy-balance method on the compressormore » that uses a compressor map for power consumption, which is relatively independent of compressor faults that influence mass flow rate. The third model is developed using an empirical correlation for an electronic expansion valve (EEV) based on an orifice equation. The three VRMFs are shown to work well in estimating refrigerant mass flow rate for various systems under fault-free conditions with less than 5% RMS error. Each of the three mass flow rate estimates can be utilized to diagnose and track the following faults: 1) loss of compressor performance, 2) fouled condenser or evaporator filter, 3) faulty expansion device, respectively. For example, a compressor refrigerant flow map model only provides an accurate estimation when the compressor operates normally. When a compressor is not delivering the expected flow due to a leaky suction or discharge valve or other internal fault, the energy-balance or EEV model can provide accurate flow estimates. In this paper, the flow differences provide an indication of loss of compressor performance and can be used for fault detection and diagnostics.« less

Transient hydrogeological controls on the chemistry of a seepage lake

USGS Publications Warehouse

Krabbenhoft, David P.; Webster, Katherine E.

1995-01-01

A solute mass balance method was used to estimate groundwater inflow and outflow rates for Nevins Lake, Michigan, a seepage lake in the upper peninsula that historically has shown extremely variable water chemistry compared with most other seepage lakes. A 4-year study (1989–1992) of the hydrology and geochemistry of Nevins Lake and its contiguous groundwater system revealed that changes in the mass of dissolved solutes are the result of annual hydraulic gradient reversals. A pronounced acidification of Nevins Lake from 1986 to 1988 was likely caused by drought-induced diminished groundwater inflow rates. In this study, dissolved calcium (the major cation in water of Nevins Lake, groundwater, and precipitation) was used for estimating mass flow rates. During the 1989–1992 period, Nevins Lake showed a reproducible annual cycle in calcium mass. Immediately following spring snowmelt and the resulting hydraulic gradient reversal, the mass of dissolved calcium in the lake increases rapidly, and then it decreases steadily throughout the summer and early fall, at which time the lake becomes hydraulically mounded and receives no groundwater inflow. Groundwater flow rates estimated by the solute mass balance method are sensitive to assumed solute concentrations in discharging groundwater. Pore water samples from the lake bed are shown to be more representative of water discharging to the lake than are samples from piezometers near the lake shore, but spatial and temporal variability in pore water chemistry must be considered. Stable isotope analyses (18O and 2H) of lake water, groundwater, and pore water samples show that water discharging to Nevins Lake in the spring is entirely recycled lake water, and no groundwater derived from terrestrial recharge reaches the lake. The conceptual model formulated during this study linking lake chemistry and the contiguous groundwater system and general groundwater flow patterns surrounding highly transient lake systems are likely transferable to other similar systems.

Basin-scale heterogeneity in Antarctic precipitation and its impact on surface mass variability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fyke, Jeremy; Lenaerts, Jan T. M.; Wang, Hailong

Annually averaged precipitation in the form of snow, the dominant term of the Antarctic Ice Sheet surface mass balance, displays large spatial and temporal variability. Here we present an analysis of spatial patterns of regional Antarctic precipitation variability and their impact on integrated Antarctic surface mass balance variability simulated as part of a preindustrial 1800-year global, fully coupled Community Earth System Model simulation. Correlation and composite analyses based on this output allow for a robust exploration of Antarctic precipitation variability. We identify statistically significant relationships between precipitation patterns across Antarctica that are corroborated by climate reanalyses, regional modeling and icemore » core records. These patterns are driven by variability in large-scale atmospheric moisture transport, which itself is characterized by decadal- to centennial-scale oscillations around the long-term mean. We suggest that this heterogeneity in Antarctic precipitation variability has a dampening effect on overall Antarctic surface mass balance variability, with implications for regulation of Antarctic-sourced sea level variability, detection of an emergent anthropogenic signal in Antarctic mass trends and identification of Antarctic mass loss accelerations.« less

Basin-scale heterogeneity in Antarctic precipitation and its impact on surface mass variability

DOE PAGES

Fyke, Jeremy; Lenaerts, Jan T. M.; Wang, Hailong

2017-11-15

Annually averaged precipitation in the form of snow, the dominant term of the Antarctic Ice Sheet surface mass balance, displays large spatial and temporal variability. Here we present an analysis of spatial patterns of regional Antarctic precipitation variability and their impact on integrated Antarctic surface mass balance variability simulated as part of a preindustrial 1800-year global, fully coupled Community Earth System Model simulation. Correlation and composite analyses based on this output allow for a robust exploration of Antarctic precipitation variability. We identify statistically significant relationships between precipitation patterns across Antarctica that are corroborated by climate reanalyses, regional modeling and icemore » core records. These patterns are driven by variability in large-scale atmospheric moisture transport, which itself is characterized by decadal- to centennial-scale oscillations around the long-term mean. We suggest that this heterogeneity in Antarctic precipitation variability has a dampening effect on overall Antarctic surface mass balance variability, with implications for regulation of Antarctic-sourced sea level variability, detection of an emergent anthropogenic signal in Antarctic mass trends and identification of Antarctic mass loss accelerations.« less

20 years of mass balances on the Piloto glacier, Las Cuevas river basin, Mendoza, Argentina

NASA Astrophysics Data System (ADS)

Leiva, J. C.; Cabrera, G. A.; Lenzano, L. E.

2007-10-01

Climatic changes of the 20th century have altered the water cycle in the Andean basins of central Argentina. The most visible change is seen in the mountain glaciers, with loss of part of their mass due to decreasing thickness and a substantial recession in the last 100 years. This paper briefly describes the results of glacier mass balance research since 1979 in the Piloto Glacier at the Cajón del Rubio, in the headwaters of Las Cuevas River, presenting new results for the period 1997-2003. Very large interannual variability of net annual specific balance is evident, due largely to variations in winter snow accumulation, with a maximum net annual value of + 151 cm w.e. and a minimum value of - 230 cm w.e. Wet El Niño years are normally associated with positive net annual balances, while dry La Niña years generally result in negative balances. Within the 24-year period, 67% of the years show negative net annual specific balances, with a cumulative mass balance loss of - 10.50 m water equivalent (w.e.). Except for exceptions normally related to El Niño events, a general decreasing trend of winter snow accumulation is evident in the record, particularly after 1992, which has a strong effect in the overall negative mass balance values. The glacier contribution to Las Cuevas River runoff is analysed based on the Punta de Vacas River gauge station for a hypothetical year without snow precipitation (YWSP), when the snowmelt component is zero. Extremely dry years similar to a YWSP have occurred in 1968-1969, 1969-1970 and 1996-1997. The Punta de Vacas gauge station is located 62 km downstream from Piloto Glacier, and the basin contains 3.0% of uncovered glacier ice and 3.7% of debris-covered ice. The total glacier contribution to Las Cuevas River discharge is calculated as 82 ± 8% during extremely dry years. If glacier wastage continues at the present trend as observed during the last 2 decades, it will severely affect the water resources in the arid central Andes of Argentina.

Model-based calculations of surface mass balance of mountain glaciers for the purpose of water consumption planning: focus on Djankuat Glacier (Central Caucasus)

NASA Astrophysics Data System (ADS)

Rybak, O. O.; Rybak, E. A.

2018-01-01

Mountain glaciers act as regulators of run-off in the summer period, which is very crucial for economy especially in dynamically developing regions with rapidly growing population, such as Central Asia or the Northern Caucasus in Russia. In overall, glaciers stabilize water consumption in comparatively arid areas and provide conditions for sustainable development of the economy in mountainous regions and in the surrounding territories. A proper prediction of the glacial run-off is required to elaborate strategies of the regional development. This goal can be achieved by implementation of mathematical modeling methods into planning methodologies. In the paper, we consider one of the first steps in glacier dynamical modeling - surface mass balance simulation. We focus on the Djankuat Glacier in the Central Caucasus, where regular observations have been conducted during the last fifty years providing an exceptional opportunity to calibrate and to validate a mathematical model.

Parse, simulation, and prediction of NOx emission across the Midwestern United States

NASA Astrophysics Data System (ADS)

Fang, H.; Michalski, G. M.; Spak, S.

2017-12-01

Accurately constraining N emissions in space and time has been a challenge for atmospheric scientists. It has been suggested that 15N isotopes may be a way of tracking N emission sources across various spatial and temporal scales. However, the complexity of multiple N sources that can quickly change in intensity has made this a difficult problem. We have used a SMOKE emission model to parse NOx emission across the Midwestern United States for a one-year simulation. An isotope mass balance methods was used to assign 15N values to road, non-road, point, and area sources. The SMOKE emissions and isotope mass balance were then combined to predict the 15N of NOx emissions (Figure 1). This ^15N of NOx emissions model was then incorporated into CMAQ to assess the role of transport and chemistry would impact the 15N value of NOx due to mixing and removal processes. The predicted 15N value of NOx was compared to those in recent measurements of NOx and atmospheric nitrate.

Flutter calculations in three degrees of freedom

NASA Technical Reports Server (NTRS)

Theodorsen, Theodore; Garrick, I E

1942-01-01

The present paper is a continuation of the general study of flutter published in NACA reports nos. 496 and 685. The paper is mainly devoted to flutter in three degrees of freedom (bending, torsion, and aileron) for which a number of selected cases have been calculated and presented in graphical form. The results are analyzed and discussed with regard to the effects of structural damping, of fractional-span ailerons, and of mass-balancing. The analysis shows that more emphasis should be put on the effect of structural damping and less on mass-balancing. The conclusion is drawn that a definite minimum amount of structural damping, which is usually found to be present, is essential in the calculations for an adequate description of the flutter case. Theoretical flutter predictions are thus brought into closer agreement with the facts of experience. A brief discussion is included of a particular biplane that had experienced flutter at about 200 miles per hour. Some simplifications have been achieved in the method of calculation. (author)

Applying an orographic precipitation model to improve mass balance modeling of the Juneau Icefield, AK

NASA Astrophysics Data System (ADS)

Roth, A. C.; Hock, R.; Schuler, T.; Bieniek, P.; Aschwanden, A.

2017-12-01

Mass loss from glaciers in Southeast Alaska is expected to alter downstream ecological systems as runoff patterns change. To investigate these potential changes under future climate scenarios, distributed glacier mass balance modeling is required. However, the spatial resolution gap between global or regional climate models and the requirements for glacier mass balance modeling studies must be addressed first. We have used a linear theory of orographic precipitation model to downscale precipitation from both the Weather Research and Forecasting (WRF) model and ERA-Interim to the Juneau Icefield region over the period 1979-2013. This implementation of the LT model is a unique parameterization that relies on the specification of snow fall speed and rain fall speed as tuning parameters to calculate the cloud time delay, τ. We assessed the LT model results by considering winter precipitation so the effect of melt was minimized. The downscaled precipitation pattern produced by the LT model captures the orographic precipitation pattern absent from the coarse resolution WRF and ERA-Interim precipitation fields. Observational data constraints limited our ability to determine a unique parameter combination and calibrate the LT model to glaciological observations. We established a reference run of parameter values based on literature and performed a sensitivity analysis of the LT model parameters, horizontal resolution, and climate input data on the average winter precipitation. The results of the reference run showed reasonable agreement with the available glaciological measurements. The precipitation pattern produced by the LT model was consistent regardless of parameter combination, horizontal resolution, and climate input data, but the precipitation amount varied strongly with these factors. Due to the consistency of the winter precipitation pattern and the uncertainty in precipitation amount, we suggest a precipitation index map approach to be used in combination with a distributed mass balance model for future mass balance modeling studies of the Juneau Icefield. The LT model has potential to be used in other regions in Alaska and elsewhere with strong orographic effects for improved glacier mass balance modeling and/or hydrological modeling.

Impact of co-digestion on existing salt and nutrient mass balances for a full-scale dairy energy project.

PubMed

Camarillo, Mary Kay; Stringfellow, William T; Spier, Chelsea L; Hanlon, Jeremy S; Domen, Jeremy K

2013-10-15

Anaerobic digestion of manure and other agricultural waste streams with subsequent energy production can result in more sustainable dairy operations; however, importation of digester feedstocks onto dairy farms alters previously established carbon, nutrient, and salinity mass balances. Salt and nutrient mass balance must be maintained to avoid groundwater contamination and salination. To better understand salt and nutrient contributions of imported methane-producing substrates, a mass balance for a full-scale dairy biomass energy project was developed for solids, carbon, nitrogen, sulfur, phosphorus, chloride, and potassium. Digester feedstocks, consisting of thickened manure flush-water slurry, screened manure solids, sudan grass silage, and feed-waste, were tracked separately in the mass balance. The error in mass balance closure for most elements was less than 5%. Manure contributed 69.2% of influent dry matter while contributing 77.7% of nitrogen, 90.9% of sulfur, and 73.4% of phosphorus. Sudan grass silage contributed high quantities of chloride and potassium, 33.3% and 43.4%, respectively, relative to the dry matter contribution of 22.3%. Five potential off-site co-digestates (egg waste, grape pomace, milk waste, pasta waste, whey wastewater) were evaluated for anaerobic digestion based on salt and nutrient content in addition to bio-methane potential. Egg waste and wine grape pomace appeared the most promising co-digestates due to their high methane potentials relative to bulk volume. Increasing power production from the current rate of 369 kW to the design value of 710 kW would require co-digestion with either 26800 L d(-1) egg waste or 60900 kg d(-1) grape pomace. However, importation of egg waste would more than double nitrogen loading, resulting in an increase of 172% above the baseline while co-digestion with grape pomace would increase potassium by 279%. Careful selection of imported co-digestates and management of digester effluent is required to manage salt and nutrient mass loadings and reduce groundwater impacts. Copyright © 2013 Elsevier Ltd. All rights reserved.

Sensitivity of glacier mass balance and equilibrium line altitude to climatic change on King George Island, Antarctic Peninsula.

NASA Astrophysics Data System (ADS)

Falk, Ulrike; Lopez, Damian; Silva-Busso, Adrian

2017-04-01

The South Shetland Islands are located at the northern tip of the Antarctic Peninsula which is among the fastest warming regions on Earth. Surface air temperature increases (ca. 3 K in 50 years) are concurrent with retreating glacier fronts, an increase in melt areas, ice surface lowering and rapid break-up and disintegration of ice shelves. Observed surface air temperature lapse rates show a high variability during winter months (standard deviations up to ±1.0 K/100 m), and a distinct spatial heterogeneity reflecting the impact of synoptic weather patterns especially during winter glacial mass accumulation periods. The increased mesocyclonic activity during the winter time in the study area results in intensified advection of warm, moist air with high temperatures and rain, and leads to melt conditions on the ice cap, fixating surface air temperatures to the melting point. The impact on winter accumulation results in even more negative mass balance estimates. Six years of glaciological measurements on mass balance stake transects are used with a glacier melt model to assess changes in melt water input to the coastal waters, glacier surface mass balance and the equilibrium line altitude. The average equilibrium line altitude (ELA) calculated from own glaciological observations for KGI over the time period 2010 - 2015 amounts to ELA=330±100 m. Published studies suggest rather stable condition slightly negative glacier mass balance until the mid 80's with an ELA of approx. 150 m. The calculated accumulation area ratio suggests rather dramatic changes in extension of the inland ice cap for the South Shetland Islands until an equilibrium with concurrent climate conditions is reached.

Osteoporosis and gait and balance disturbances in older sarcopenic obese New Zealanders.

PubMed

Waters, D L; Hale, L; Grant, A M; Herbison, P; Goulding, A

2010-02-01

Bone, muscle, and fat may affect gait and balance in older adults. Osteoporosis was prevalent in low muscle mass participants and related to gait and balance deficits. Low muscle combined with high fat mass had more functional deficits and poorer bone health, which has implications for falls risk and fractures. Decreasing bone density and muscle mass and increasing fat mass may act synergistically to affect gait and balance in older adults. One hundred eighty-three older adults (age 72.7 +/- 6 years, range 56-93; body mass index 28.2 +/- 4.9, range 16.6-46.0) were recruited from a New Zealand falls prevention intervention trial. Total and appendicular skeletal muscle mass (ASM), percent fat, and bone mineralization were assessed by dual energy X-ray absorptiometry and used to characterize normal lean (NL, n = 51), sarcopenic (SS, n = 18), sarcopenic obese (SO, n = 29), and obese (OO, n = 85) phenotypes. Functional performance was assessed using timed up and go, chair stand, single leg stand, and step test. Regression models were adjusted for age, sex, medications, and physical activity. Femoral neck osteoporosis was present in 22% SS, 17% SO, 12% NL, and 7% OO. Femoral neck osteoporosis with low ASM predicted poor chair stand performance (beta -3.3, standard error 1.6, p = 0.04). SO scored lowest on the chair stand (p = 0.03) and step test (p = 0.03). Higher ASM predicted faster timed up and go performance (p = 0.001). Osteoporosis was prevalent in low ASM groups (SS and SO) and related to gait and balance deficits, particularly in the SO. This has implications for falls risk, fractures, and interventions.

Body mass, energy intake, and water consumption of rats and humans during space flight

NASA Technical Reports Server (NTRS)

Wade, C. E.; Miller, M. M.; Baer, L. A.; Moran, M. M.; Steele, M. K.; Stein, T. P.

2002-01-01

Alteration of metabolism has been suggested as a major limiting factor to long-term space flight. In humans and primates, a negative energy balance has been reported. The metabolic response of rats to space flight has been suggested to result in a negative energy balance. We hypothesized that rats flown in space would maintain energy balance as indicated by maintenance of caloric intake and body mass gain. Further, the metabolism of the rat would be similar to that of laboratory-reared animals. We studied the results from 15 space flights lasting 4 to 19 d. There was no difference in average body weight (206 +/- 13.9 versus 206 +/- 14.8 g), body weight gain (5.8 +/- 0.48 versus 5.9 +/- 0.56 g/d), caloric intake (309 +/- 21.0 versus 309 +/- 20.1 kcal/kg of body mass per day), or water intake (200 +/- 8.6 versus 199 +/- 9.3 mL/kg of body mass per day) between flight and ground control animals. Compared with standard laboratory animals of similar body mass, no differences were noted. The observations suggested that the negative balance observed in humans and non-human primates may be due to other factors in the space-flight environment.

Development, calibration, and sensitivity analyses of a high-resolution dissolved oxygen mass balance model for the northern Gulf of Mexico

EPA Science Inventory

A high-resolution dissolved oxygen mass balance model was developed for the Louisiana coastal shelf in the northern Gulf of Mexico. GoMDOM (Gulf of Mexico Dissolved Oxygen Model) was developed to assist in evaluating the impacts of nutrient loading on hypoxia development and exte...

SOURCE APPORTIONMENT OF PM 2.5 AND CARBON IN SEATTLE USING CHEMICAL MASS BALANCE AND POSITIVE MATRIX FACTORIZATION

EPA Science Inventory

Three years of PM2.5 speciated data were collected and chemically analyzed using the IMPROVE protocol at the Beacon Hill site in Seattle. The data were analyzed by the Chemical Mass Balance Version 8 (CMB8) and Positive Matrix Factorization (PMF) source apportionment models. T...

EVIDENCE OF FEED CONTAMINATION DUE TO SAMPLE HANDLING AND PREPARATION DURING A MASS BALANCE STUDY OF DIOXINS IN LACTATING COWS IN BACKGROUND CONDITIONS

EPA Science Inventory

In 1997, the United States (US) Environmental Protection Agency (EPA) conducted a mass balance study of polychlorinated dibenzo-p-dioxins (CDDs) and dibenzofurans (CDFs) in lactating cows in background conditions. The field portion of the study occurred at the US Department of A...

DEVELOPMENT, CALIBRATION AND APPLICATION OF A CONTAINMENT TRANSPORT AND FATE MASS BALANCE MODEL IN LAKE MICHIGAN, LM2

EPA Science Inventory

The Lake Michigan Mass Balance Project (LMMBP) was initiated to support the development of a Lake Wide Management Plan (LaMP) for Lake Michigan. As one of the models in the LMMBP modeling framework, the Level 2 Lake Michigan containment transport and fate (LM2) model has been dev...

Model Construct and Calibration of an Integrated Water Quality Model (LM2-Toxic) for the Lake Michigan Mass Balance Project

EPA Science Inventory

The Lake Michigan Mass Balance Project (LMMBP) is a part of the Enhanced Monitoring Plan (EMP) for Lake Michigan (McCarty, et al., 2006). PCBs (polychlorinated biphenyls) were one of the targeted pollutants studied in the project. As one of the components in the overall LMMBP mod...

A Simplified Model of Human Alcohol Metabolism That Integrates Biotechnology and Human Health into a Mass Balance Team Project

ERIC Educational Resources Information Center

Yang, Allen H. J.; Dimiduk, Kathryn; Daniel, Susan

2011-01-01

We present a simplified human alcohol metabolism model for a mass balance team project. Students explore aspects of engineering in biotechnology: designing/modeling biological systems, testing the design/model, evaluating new conditions, and exploring cutting-edge "lab-on-a-chip" research. This project highlights chemical engineering's impact on…

DOCUMENTATION FOR THE GRIDDED HOURLY ATRAZINE EMISSIONS DATA SET FOR THE LAKE MICHIGAN MASS BALANCE STUDY: A FINAL CONTRACT REPORT

EPA Science Inventory

In order to develop effective strategies for toxics management, the Great Lakes National Program Office (GLNPO) of the United States Environmental Protection Agency (U.S. EPA), in 1994, launched an ambitious five year program to conduct a mass balance study of selected toxics p...

Systematic Approach to Calculate the Concentration of Chemical Species in Multi-Equilibrium Problems

ERIC Educational Resources Information Center

Baeza-Baeza, Juan Jose; Garcia-Alvarez-Coque, Maria Celia

2011-01-01

A general systematic approach is proposed for the numerical calculation of multi-equilibrium problems. The approach involves several steps: (i) the establishment of balances involving the chemical species in solution (e.g., mass balances, charge balance, and stoichiometric balance for the reaction products), (ii) the selection of the unknowns (the…

What Drives Saline Circulation Cells in Coastal Aquifers? An Energy Balance for Density-Driven Groundwater Systems

NASA Astrophysics Data System (ADS)

Harvey, C. F.; Michael, H. A.

2017-12-01

We formulate the energy balance for coastal groundwater systems and apply it to: (1) Explain the energy driving offshore saline circulation cells, and; (2) Assess the accuracy of numerical simulations of coastal groundwater systems. The flow of fresh groundwater to the ocean is driven by the loss of potential energy as groundwater drops from the elevation of the inland watertable, where recharge occurs, to discharge at sea level. This freshwater flow creates an underlying circulation cell of seawater, drawn into coastal aquifers offshore and discharging near shore, that adds to total submarine groundwater discharge. The saline water in the circulation cell enters and exits the aquifer through the sea floor at the same hydraulic potential. Existing theory explains that the saline circulation cell is driven by mixing of fresh and saline without any additional source of potential or mechanical power. This explanation raises a basic thermodynamic question: what is the source of energy that drives the saline circulation cell? Here, we resolve this question by building upon Hubbert's conception of hydraulic potential to formulate an energy balance for density-dependent flow and salt transport through an aquifer. We show that, because local energy dissipation within the aquifer is proportional to the square of the groundwater velocity, more groundwater flow may be driven through an aquifer for a given energy input if local variations in velocity are smoothed. Our numerical simulations of coastal groundwater systems show that dispersion of salt across the fresh-saline interface spreads flow over larger volumes of the aquifer, smoothing the velocity field, and increasing total flow and submarine groundwater discharge without consuming more power. The energy balance also provides a criterion, in addition to conventional mass balances, for judging the accuracy of numerical solutions of non-linear density-dependent flow problems. Our results show that some numerical simulations of saline circulation converge to excellent balances of both mass and energy, but that other simulations may poorly balance energy even after converging to a good mass balance. Thus, the energy balance can be used to identify incorrect simulations that pass convential mass balance criteria for accuracy.

Fast Pyrolysis of Biomass Residues in a Twin-screw Mixing Reactor

PubMed Central

Funke, Axel; Richter, Daniel; Niebel, Andreas; Dahmen, Nicolaus; Sauer, Jörg

2016-01-01

Fast pyrolysis is being increasingly applied in commercial plants worldwide. They run exclusively on woody biomass, which has favorable properties for conversion with fast pyrolysis. In order to increase the synergies of food production and the energetic and/or material use of biomass, it is desirable to utilize residues from agricultural production, e.g., straw. The presented method is suitable for converting such a material on an industrial scale. The main features are presented and an example of mass balances from the conversion of several biomass residues is given. After conversion, fractionated condensation is applied in order to retrieve two condensates — an organic-rich and an aqueous-rich one. This design prevents the production of fast pyrolysis bio-oil that exhibits phase separation. A two phase bio-oil is to be expected because of the typically high ash content of straw biomass, which promotes the production of water of reaction during conversion. Both fractionated condensation and the use of biomass with high ash content demand a careful approach for establishing balances. Not all kind of balances are both meaningful and comparable to other results from the literature. Different balancing methods are presented, and the information that can be derived from them is discussed. PMID:27684439

Acute effects of rearfoot manipulation on dynamic standing balance in healthy individuals.

PubMed

Wassinger, Craig A; Rockett, Ariel; Pitman, Lucas; Murphy, Matthew Matt; Peters, Charles

2014-06-01

Dynamic standing balance is essential to perform functional activities and is included in the treatment of many lower extremity injuries. Physiotherapists utilize many methods to restore standing balance including stability exercises, functional retraining, and manual therapy. The purpose of this study was to investigate the effects of a rearfoot distraction manipulation on dynamic standing balance. Twenty healthy participants (age: 24.4 ± 2.8 years; height: 162.9 ± 37.7 cm; mass: 68.0 ± 4.8 kg; right leg dominant = 20) completed this study. Following familiarization, dynamic standing balance was assessed during: (1) an experimental condition immediately following a rearfoot distraction manipulation, and (2) a control condition. Dominant leg balance was quantified using the Y-balance test which measures lower extremity reach distances. Reach distances were normalized to leg length and measured in the anterior, posteromedial and posterolateral directions. Overall balance was calculated through the summing of all normalized directions. Paired t-tests and Wilcoxon rank tests were used to compare balance scores for parametric and non-parametric data as appropriate. Significance was set at 0.05 a priori. Effect size (ES) was calculated to determine the clinical impact of the manipulation. Increased reach distances (indicating improved balance) were noted following manipulation for overall balance (p = 0.03, ES = 0.26) and in the posteromedial direction (p = 0.01, ES = 0.42). Reach distances did not differ for the anterior (p = 0.11, ES = 0.16) or posterolateral (p = 0.11, ES = 0.25) components. Dynamic standing balance improved after a rearfoot distraction manipulation in healthy participants. It is hypothesized that manual therapy applied to the foot and ankle may be beneficial to augment other therapeutic modalities when working with patients to improve dynamic standing balance. Copyright © 2013 Elsevier Ltd. All rights reserved.

The relationship between balance confidence and control in individuals with Parkinson's disease

PubMed Central

Lee, Hyo Keun; Altman, Lori J.P.; McFarland, Nikolaus; Hass, Chris J.

2016-01-01

Introduction A broad range of subjective and objective assessments have been used to assess balance confidence and balance control in persons with Parkinson's disease (PD). However, little is known about the relationship between self-perceived balance confidence and actual balance control in PD. The purpose of this investigation was to determine the relationship between self-perceived balance confidence and objectively measured static/dynamic balance control abilities. Methods Forty-four individuals with PD participated in the study. Patients were stratified into 2 groups based on the modified Hoehn and Yahr (H&Y) disability score: early stage, H&Y≤2.0 and moderate stage, H&Y ≥2.5. All participants completed the activities-specific balance confidence (ABC) scale and performed standing balance and gait initiation tasks to assess static and dynamic balance control. The center of pressure (COP) sway (CE95%Sway) during static balance and the peak distance between the projections of the COP and the center of mass (COM) in the transverse plane (COPCOM) during gait initiation were calculated. Pearson correlation analyses were conducted relating the ABC score and CE95%Sway and COPCOM. Results For early stage PD, there was a moderate correlation between ABC score and CE95 %Sway (r=-0.56, R2=0.32, p=0.002), while no significant correlation was found between ABC score and COPCOM (r=-0.24, R2=0.06, p=0.227). For moderate stage PD, there was a moderate correlation between ABC score and COPCOM (r=0.49, R2=0.24, p=0.044), while no correlation was found between ABC score and CE95%Sway (r=-0.19, R2=0.04, p=0.478). Conclusion Individuals with different disease severities showed different relationships between balance confidence and actual static/dynamic balance control. PMID:26949065

FOREWORD: Special issue on mass

NASA Astrophysics Data System (ADS)

Gläser, Michael

2003-12-01

This special issue is intended to present a review of mass standards, mass determination and the efforts to replace the international prototype of the kilogram by a new definition of the kilogram based on a fundamental constant of physics. Mass is a quantity that is familiar to everybody primarily for its importance in commerce. It is not only one of the traditional quantities of metrology but also of science in general. The unit of mass has always been based on a material object and, since 1889, on the international prototype of the kilogram. The mass of any standard weight is derived from this prototype by a cascade of comparison measurements using balances. The sources of uncertainty of the mass of a standard depend upon the circumstances of the weighing process and the long-term instabilities of the intermediate standards. The international prototype—its mass is one kilogram by definition—may also suffer from instabilities or drifts in time, but until now it has not been possible to check this by comparison with a fundamental constant in physics. Repeated verifications of some 40 or so national prototypes of the members of the Metre Convention have shown significant drifts with an average of about 50 µg within 100 years, a fact that casts doubt on the stability of the international prototype itself. Experiments have been underway for about 30 years on linking fundamental constants such as the Avogadro constant or, correspondingly, the atomic mass unit and Planck's constant to the kilogram. Relative uncertainties of the order of 10-7 have been reached today, still one order of magnitude too large for monitoring the stability of the international prototype or for a new definition. The first article of this special issue gives information on the international and the national prototypes of the kilogram, its material, manufacture, cleaning procedures, stability investigations and the periodic verifications of national prototypes. The next article describes methods for determining the mass of multiples and submultiples of the kilogram. In practice, mass standards in the range from one milligram up to several thousands of kilograms are used for the mass determination of commercial objects or for the calibration of weighing instruments. The determination of the mass of multiples and submultiples of the kilogram is a procedure that links such mass standards to the kilogram by a number of—mostly redundant—weighing processes and mathematical procedures that result in the values and the uncertainties of the standards involved. The reproducibility of E-class weights is the topic of the next article. Classification of weights is defined in an international recommendation for legal metrology and is carried over into the national regulations of most countries. E-class weights are at the highest level in this context. Reproducibility is related to the instability of mass standards within some time interval. Corresponding observations and discussions of the results are reported. As already mentioned, weighing is an important source of the uncertainty of a mass standard. The requirements on weighing in legal metrology are discussed in the following article. It refers to the project of a new international recommendation for weights (revised OIML R 111) that describes procedures for mass determination and for testing the properties of weights according to the stated requirements for the different classes. The instability of mass standards is mostly due to surface contamination. A review of the stability of platinum-iridium and stainless-steel standards and their surface contamination is presented in the next article. It gives a comprehensive overview of published data and investigations on this topic. Magnetic weights interact with the magnetic field generated by a balance. A change in the balance indication is the consequence if certain limits are exceeded. Magnetic properties of weights, their measurements and magnetic interactions between weights and balances constitute the theme of the next article. After an introduction to the theoretical aspects of magnetic fields and magnetic forces, different measurement methods, international comparisons in this field, modelling the interacting forces and finally the impact on the new international recommendation for weights are presented. The moving-coil Watt balance and the superconducting magnetic levitation experiment are two of the experiments aimed at redefining the kilogram. 'Tracing Planck's constant to the kilogram by electromechanical methods' is the title of the corresponding article. It describes the principles of these experiments and reviews the efforts and results achieved at present in the laboratories concerned. Another approach to redefining the kilogram is reviewed in the article entitled 'Tracing the definition of the kilogram to the Avogadro constant using a silicon single crystal'. This approach is performed in a worldwide collaboration coordinated by the Working Group on the Avogadro Constant of the CIPM Consultative Committee for Mass and related quantities. An experiment for determining the atomic mass unit by ion accumulation follows a straightforward way for determining the mass of an atom by collecting ions, weighing and 'counting' them by measuring their total charge. This article reports on a 'third' way of redefining the kilogram. This approach is followed by only one laboratory and it is still at an early stage compared with the uncertainties already achieved by the other ones.

Wave propagation modeling in composites reinforced by randomly oriented fibers

NASA Astrophysics Data System (ADS)

Kudela, Pawel; Radzienski, Maciej; Ostachowicz, Wieslaw

2018-02-01

A new method for prediction of elastic constants in randomly oriented fiber composites is proposed. It is based on mechanics of composites, the rule of mixtures and total mass balance tailored to the spectral element mesh composed of 3D brick elements. Selected elastic properties predicted by the proposed method are compared with values obtained by another theoretical method. The proposed method is applied for simulation of Lamb waves in glass-epoxy composite plate reinforced by randomly oriented fibers. Full wavefield measurements conducted by the scanning laser Doppler vibrometer are in good agreement with simulations performed by using the time domain spectral element method.

Firn Thickness Changes (1982-2015) Driven by SMB from MERRA-2, RACMO2.3, ERA-Int and AVHRR Surface Temperature and the Impacts to Greenland Ice Sheet Mass Balance

NASA Astrophysics Data System (ADS)

Li, J.; Medley, B.; Neumann, T.; Smith, B. E.; Luthcke, S. B.; Zwally, H. J.

2016-12-01

Surface mass balance (SMB) data are essential in the derivation of ice sheet mass balance. This is because ice sheet mass change consists of short-term and long-term variations. The short-term variations are directly given by the SMB data. For altimetry based ice sheet mass balance studies, these short-term mass changes are converted to firn thickness changes by using a firn densification-elevation model, and then the variations are subtracted from the altimetry measurements to give the long-term ice thickness changes that are associated with the density of ice. So far various SMB data sets such as ERA-Interim, RACMO and MERRA are available and some have been widely used in large number of ice sheet mass balance studies. However theses data sets exhibit the clear discrepancies in both random and systematic manner. In this study, we use our time dependent firn densification- elevation model, driven by the SMB data from MERRA-2, RACMO2.3 and ERA-Int for the period of 1982-2015 and the temperature variations from AVHRR for the same period to examine the corresponding firn thickness variations and the impacts to the mass changes over the Greenland ice sheet. The model was initialized with the1980's climate. Our results show that the relative smaller (centimeter level) differences in the firn thickness driven by the different data set occur at the early stage (1980's) of the model run. As the time progressing, the discrepancies between the SMB data sets accumulate, and the corresponding firn thickness differences quickly become larger with the value > 2m at the end of the period. Although the overall rates for the whole period driven by each of the three data sets are small ranging -0.2 - 0.2 cm a-1 (-3.0-2.7 Gt a-1), the decadal rates can vary greatly with magnitude > 3 cm a-1 and the impact to the Greenland mass change exceeds 30 Gt a-1.

Uncertainty evaluation of mass values determined by electronic balances in analytical chemistry: a new method to correct for air buoyancy.

PubMed

Wunderli, S; Fortunato, G; Reichmuth, A; Richard, Ph

2003-06-01

A new method to correct for the largest systematic influence in mass determination-air buoyancy-is outlined. A full description of the most relevant influence parameters is given and the combined measurement uncertainty is evaluated according to the ISO-GUM approach [1]. A new correction method for air buoyancy using an artefact is presented. This method has the advantage that only a mass artefact is used to correct for air buoyancy. The classical approach demands the determination of the air density and therefore suitable equipment to measure at least the air temperature, the air pressure and the relative air humidity within the demanded uncertainties (i.e. three independent measurement tasks have to be performed simultaneously). The calculated uncertainty is lower for the classical method. However a field laboratory may not always be in possession of fully traceable measurement systems for these room climatic parameters.A comparison of three approaches applied to the calculation of the combined uncertainty of mass values is presented. Namely the classical determination of air buoyancy, the artefact method, and the neglecting of this systematic effect as proposed in the new EURACHEM/CITAC guide [2]. The artefact method is suitable for high-precision measurement in analytical chemistry and especially for the production of certified reference materials, reference values and analytical chemical reference materials. The method could also be used either for volume determination of solids or for air density measurement by an independent method.

Finding the Density of a Liquid Using a Metre Rule

ERIC Educational Resources Information Center

Chattopadhyay, K. N.

2008-01-01

A simple method, which is based on the principle of moment of forces only, is described for the determination of the density of liquids without measuring the mass and volume. At first, an empty test tube and a solid substance, which are hung on each side of a metre rule, are balanced and the moment arm of the test tube is measured. Keeping the…

Isotopic Estimation of Water Balance and Groundwater-Surface Water Interactions of Tropical Wetland Lakes in the Pantanal, Brazil

NASA Astrophysics Data System (ADS)

Schwerdtfeger, J.; Johnson, M. S.; Weiler, M.; Couto, E. G.

2009-12-01

The Pantanal is the largest and most pristine wetland of the world, yet hydrological research there is still in its infancy. In particular the water balance of the millions of lakes and ponds and their interaction with the groundwater and the rivers are not known. The aim of this study was to assess the hydrological behaviour between different water bodies in the dry season of the northern Pantanal wetland, Brazil, to provide a more general understanding of the hydrological functioning of tropical floodplain lakes and surface water-groundwater interactions of wetlands. In the field 6-9 water sample of seven different lakes were taken during 3 months and were analyzed for stable water isotopes and chloride. In addition meteorological data from a nearby station was used to estimate daily evaporation from the water surface. This information was then used to predict the hydrological dynamics to determine whether the lakes are evaporation-controlled or throughflow-dominated systems. A chloride mass balance served to evaluate whether Cl- enrichment took place due to evaporation only, or whether the system has significant inflow and/or outflow rates. The results of those methods showed that for all lakes the water budget in the dry season, output was controlled by strong evaporation while significant inflow rates were also apparent. Inflow rates and their specific concentrations in stable isotopes and chloride were successfully estimated using the simple mass balance model MINA TrêS. This approach enabled us to calculate the water balance for the lakes as well as providing an information on source water flowing into the lakes.

The potential for behavioral thermoregulation to buffer "cold-blooded" animals against climate warming.

PubMed

Kearney, Michael; Shine, Richard; Porter, Warren P

2009-03-10

Increasing concern about the impacts of global warming on biodiversity has stimulated extensive discussion, but methods to translate broad-scale shifts in climate into direct impacts on living animals remain simplistic. A key missing element from models of climatic change impacts on animals is the buffering influence of behavioral thermoregulation. Here, we show how behavioral and mass/energy balance models can be combined with spatial data on climate, topography, and vegetation to predict impacts of increased air temperature on thermoregulating ectotherms such as reptiles and insects (a large portion of global biodiversity). We show that for most "cold-blooded" terrestrial animals, the primary thermal challenge is not to attain high body temperatures (although this is important in temperate environments) but to stay cool (particularly in tropical and desert areas, where ectotherm biodiversity is greatest). The impact of climate warming on thermoregulating ectotherms will depend critically on how changes in vegetation cover alter the availability of shade as well as the animals' capacities to alter their seasonal timing of activity and reproduction. Warmer environments also may increase maintenance energy costs while simultaneously constraining activity time, putting pressure on mass and energy budgets. Energy- and mass-balance models provide a general method to integrate the complexity of these direct interactions between organisms and climate into spatial predictions of the impact of climate change on biodiversity. This methodology allows quantitative organism- and habitat-specific assessments of climate change impacts.

The potential for behavioral thermoregulation to buffer “cold-blooded” animals against climate warming

PubMed Central

Kearney, Michael; Shine, Richard; Porter, Warren P.

2009-01-01

Increasing concern about the impacts of global warming on biodiversity has stimulated extensive discussion, but methods to translate broad-scale shifts in climate into direct impacts on living animals remain simplistic. A key missing element from models of climatic change impacts on animals is the buffering influence of behavioral thermoregulation. Here, we show how behavioral and mass/energy balance models can be combined with spatial data on climate, topography, and vegetation to predict impacts of increased air temperature on thermoregulating ectotherms such as reptiles and insects (a large portion of global biodiversity). We show that for most “cold-blooded” terrestrial animals, the primary thermal challenge is not to attain high body temperatures (although this is important in temperate environments) but to stay cool (particularly in tropical and desert areas, where ectotherm biodiversity is greatest). The impact of climate warming on thermoregulating ectotherms will depend critically on how changes in vegetation cover alter the availability of shade as well as the animals' capacities to alter their seasonal timing of activity and reproduction. Warmer environments also may increase maintenance energy costs while simultaneously constraining activity time, putting pressure on mass and energy budgets. Energy- and mass-balance models provide a general method to integrate the complexity of these direct interactions between organisms and climate into spatial predictions of the impact of climate change on biodiversity. This methodology allows quantitative organism- and habitat-specific assessments of climate change impacts. PMID:19234117

Growth monitoring and control in complex medium: a case study employing fed-batch penicillin fermentation and computer-aided on-line mass balancing.

PubMed

Mou, D G; Cooney, C L

1983-01-01

To broaden the practicality of on-line growth monitoring and control, its application in fedbatch penicillin fermentation using high corn steep liquor (CSL) concentration (53 g/L) is demonstrated. By employing a calculation method that considers the vagaries of CSL consumption, overall and instantaneous carbon-balancing equations are successfully used to calculate, on-line, the cell concentration and instantaneous specific growth rate in the penicillin production phase. As a consequence, these equations, together with a feedback control strategy, enable the computer control of glucose feed and maintenance of the preselected production-phase growth rate with error less than 0.002 h(-1).

A mass-balance code for the quantitative interpretation of fluid column profiles in ground-water studies

NASA Astrophysics Data System (ADS)

Paillet, Frederick

2012-08-01

A simple mass-balance code allows effective modeling of conventional fluid column resistivity logs in dilution tests involving column replacement with either distilled water or dilute brine. Modeling a series of column profiles where the inflowing formation water introduces water quality interfaces propagating along the borehole gives effective estimates of the rate of borehole flow. Application of the dilution model yields estimates of borehole flow rates that agree with measurements made with the heat-pulse flowmeter under ambient and pumping conditions. Model dilution experiments are used to demonstrate how dilution logging can extend the range of borehole flow measurement at least an order of magnitude beyond that achieved with flowmeters. However, dilution logging has the same dynamic range limitation encountered with flowmeters because it is difficult to detect and characterize flow zones that contribute a small fraction of total flow when that contribution is superimposed on a larger flow. When the smaller contribution is located below the primary zone, ambient downflow may disguise the zone if pumping is not strong enough to reverse the outflow. This situation can be addressed by increased pumping. But this is likely to make the moveout of water quality interfaces too fast to measure in the upper part of the borehole, so that a combination of flowmeter and dilution method may be more appropriate. Numerical experiments show that the expected weak horizontal flow across the borehole at conductive zones would be almost impossible to recognize if any ambient vertical flow is present. In situations where natural water quality differences occur such as flowing boreholes or injection experiments, the simple mass-balance code can be used to quantitatively model the evolution of fluid column logs. Otherwise, dilution experiments can be combined with high-resolution flowmeter profiles to obtain results not attainable using either method alone.

Geochemical cycling, mass balance, and Earth’s dynamic structure (Invited)

NASA Astrophysics Data System (ADS)

Allegre, C. J.

2009-12-01

The use of radiogenic tracers is now established as one of the standard methods (together with seismic tomography) to constrain Earth models. One of the advantages of radiogenic tracers is that they constrain not only present day structures, but also their historical evolution since the earliest time. A mandatory condition is to use not only one but all of the available isotopic systems, with their diverse cycling properties and different radioactive half-lives. Mass balances calculations are the basic tool which allows one to use quantitatively the various tracers. However, the inverse method approach, when applied to mass balance, is strongly non-linear, particularly for tracers with intermediate to short half lives. 142Nd, 82W, and 129Xe allows one to define a consistent model for the Present and past evolutions. Results point to a 3-layer model for the present mantle: an upper mantle with two layers separated by the 450 km discontinuity, and a lower mantle below the 670 km discontinuity. These layers all convect independently though none of them is fully isolated. They exchange matter and energy, not necessarily through the same process. For instance, most hotspots (though not all of them!) are boundary layer instabilities generated at the 670 km discontinuity, but there is important heat transfer from the lower mantle through megablobs. Recent results on the Hadean period are in agreement with core-mantle- atmosphere differentiation at 4444 My. The early crust was mostly anorthositic but has been recycled into the upper mantle within the first billion years. Formation of granitic continents started at 4300 My. 80% of their material was already present on the surface as acidic rocks by 2500 My. The reworking process involved in continental development increased continuously with time and today is the dominant process. Continents are now in a stage of steady state, with general addition of mantle and subducted continental material.

Variations in surface water-ground water interactions along a headwater mountain stream : comparisons between transient storage and water balance analyses

USGS Publications Warehouse

Ward, Adam S.; Payn, Robert A.; Gooseff, Michael N.; McGlynn, Brian L.; Bencala, Kenneth E.; Kelleher, Christa A.; Wondzell, Steven M.; Wagener, Thorsten

2013-01-01

The accumulation of discharge along a stream valley is frequently assumed to be the primary control on solute transport processes. Relationships of both increasing and decreasing transient storage, and decreased gross losses of stream water have been reported with increasing discharge; however, we have yet to validate these relationships with extensive field study. We conducted transient storage and mass recovery analyses of artificial tracer studies completed for 28 contiguous 100 m reaches along a stream valley, repeated under four base-flow conditions. We calculated net and gross gains and losses, temporal moments of tracer breakthrough curves, and best fit transient storage model parameters (with uncertainty estimates) for 106 individual tracer injections. Results supported predictions that gross loss of channel water would decrease with increased discharge. However, results showed no clear relationship between discharge and transient storage, and further analysis of solute tracer methods demonstrated that the lack of this relation may be explained by uncertainty and equifinality in the transient storage model framework. Furthermore, comparison of water balance and transient storage approaches reveals complications in clear interpretation of either method due to changes in advective transport time, which sets a the temporal boundary separating transient storage and channel water balance. We have little ability to parse this limitation of solute tracer methods from the physical processes we seek to study. We suggest the combined analysis of both transient storage and channel water balance more completely characterizes transport of solutes in stream networks than can be inferred from either method alone.

The Influence of Intensifying Irrigation on Glacier Mass Balances in High Mountain Asia

NASA Astrophysics Data System (ADS)

de Kok, R.; Tuinenburg, O.; Bonekamp, P. N. J.; Immerzeel, W. W.

2017-12-01

Melt water from snow and glaciers in High Mountain Asia provide a major source of water for millions of inhabitants in the downstream low lying plains. This densely populated region also hosts some of the largest areas of irrigated land in the world. Not only is the water from High Mountain Asia important as a source of irrigation water, the irrigation itself might also change the regional, and even global, climate by increasing atmospheric moisture and by cooling the surface through evapotranspiration. We explore the effect of irrigation in the region on the synoptic climate patterns in High Mountain Asia using the WRF regional climate model. By studying the changes in the energy balance, temperatures and precipitation, we assess how the changes in irrigation patterns may have contributed to the observed trends in mountain climates and associated glacier mass balances. Initial results show that the intensifying irrigation during the last decades causes an increase in summer snowfall in the mountains in Central Karakoram and Kunlun Shan, which are the regions where slight positive mass balances have been observed in recent years. A moisture tracking model confirms that the irrigated areas are a significant moisture source for summer precipitation in High Mountain Asia. These results thus suggest that irrigation may significantly influence glaciers in High Mountain Asia, especially in the regions of observed anomalous mass balance.

Where to locate a tree plantation within a low rainfall catchment to minimise impacts on groundwater resources

NASA Astrophysics Data System (ADS)

Dean, J. F.; Webb, J. A.; Jacobsen, G. E.; Chisari, R.; Dresel, P. E.

2014-08-01

Despite the fact that there are many studies that consider the impacts of plantation forestry on water resources, and others that explore the spatial heterogeneity of groundwater recharge in dry regions, there is little marriage of the two subjects in forestry management guidelines and legislation. Here we carry out an in-depth analysis of the groundwater and surface water regime in a low rainfall, high evapotranspiration paired catchment study to examine the impact of reforestation, using water table fluctuations and chloride mass balance methods to estimate groundwater recharge. Recharge estimations using the chloride mass balance method were shown to be more likely representative of groundwater recharge regimes prior to the planting of the trees, and most likely prior to widespread land clearance by European settlers. These estimations were complicated by large amounts of recharge occurring as a result of runoff and streamflow in the lower parts of the catchment. Water table fluctuation method estimations of recharge verified that groundwater recharge occurs predominantly in the lowland areas of the study catchment. This leads to the conclusion that spatial variations in recharge are important considerations for locating tree plantations with respect to conserving water resources for downstream users. For dry regions, this means planting trees in the upland parts of the catchments, as recharge is shown to occur predominantly in the lowland areas.

Estimation of groundwater discharge and associated chemical fluxes into Poyang Lake, China: approaches using stable isotopes (δD and δ18O) and radon

NASA Astrophysics Data System (ADS)

Liao, Fu; Wang, Guangcai; Shi, Zheming; Cheng, Guoqiang; Kong, Qingmin; Mu, Wenqing; Guo, Liang

2018-05-01

Poyang Lake is the largest freshwater lake in China and is well known for its ecological and economic importance. Understanding the contribution of groundwater to Poyang Lake is important for the lake's protection and management. In this study, stable isotopes (δD and δ18O), 222Rn measurements, and corresponding models (222Rn and 18O mass balance models) were employed to evaluate the groundwater discharge and associated chemical inputs to Poyang Lake. The results showed that the distribution of δ18O in the lake water reflects the groundwater discharge into the lake. The groundwater discharge estimated using the 222Rn mass balance model was in reasonable agreement with the groundwater discharge derived from the 18O mass balance model. The 222Rn mass balance model showed that the groundwater discharge rate was 24.18 ± 6.85 mm/d with a groundwater discharge flux of (2.24 ± 0.63) × 107 m3/d, which accounts for 6.52-11.14% of river-water input in the Poyang Lake area. The groundwater discharge flux estimated using the 18O mass balance model was 3.17 × 107 m3/d, and the average groundwater discharge rate was 26.62 mm/d. The estimated groundwater discharge was used to estimate the associated chemical fluxes. It was found that groundwater-derived heavy metals such as iron and manganese are potential threats to the lake ecological system because of their large inputs from groundwater discharge.

Evaluating the degradation, sorption, and negative mass balances of pharmaceuticals and personal care products during wastewater treatment.

PubMed

Blair, Benjamin; Nikolaus, Adam; Hedman, Curtis; Klaper, Rebecca; Grundl, Timothy

2015-09-01

Conventional activated sludge (CAS) wastewater treatment processes are insufficient at removing many pharmaceutical and personal care products (PPCPs) from wastewater. In addition, negative mass balances, where the effluent concentration is greater than the influent concentration, have been observed in wastewater treatment studies and a further understanding of these results is needed. In this study, the fate and occurrence of 57 PPCPs and hormones were evaluated in an activated sludge process and the mass balances were determined. The goal of the project was to understand the PPCPs biological degradation and the extent of sorption to solids. The samples containing in situ PPCPs (i.e. samples were not spiked with additional PPCPs) were evaluated. Forty-eight of the PPCPs were detected in the soluble form and 29 were detected sorbed to solids. Two notable results were found. First, the results of this study indicate a subset of the highly biodegradable PPCPs stop being degraded at low, yet notable, concentrations. Second, the results revealed that negative mass balances were present for a subset of the PPCPs when evaluating both the soluble and sorbed concentration, for example carbamazepine and ofloxacin. Desorption from solids was not found to attribute to negative mass balances. Overall, the results from this study provide new insights into the fate of PPCPs during CAS wastewater treatment by evaluating the degradation kinetics and sorption and the results may explain the consistent levels of highly degradable PPCPs being emitted from WWTPs worldwide. Copyright © 2015 Elsevier Ltd. All rights reserved.

A theory of wheelchair wheelie performance.

PubMed

Kauzlarich, J J; Thacker, J G

1987-01-01

The results of this analytical study of wheelchair wheelie performance can be summarized into two wheelchair design equations, or rules of thumb, as developed in the paper. The equation containing the significant parameters involved in popping a wheelie for curb climbing is: fh = 0.8 mg theta c.g. [A] where fh is handrim force, m is the mass of the wheelchair + user less rear wheels, g is acceleration of gravity (9.807 m/s2), and theta c.g. is "c.g. angle," i.e., the angle between the vertical through the rear axle and a line connecting the rear axle and the system center-of-gravity. Equation [A] shows that reducing the mass and/or the c.g. angle will make it easier to pop a wheelie. The c.g. angle is reduced by moving the rear axle position forward on the wheelchair. Wheelie balance is the other aspect of performance considered; where the user balances the wheelchair on the rear wheels for going down curbs or just for fun. The ease with which a system can be controlled (balanced) is related to the static stability of the system. The static stability is defined as: omega 2 = mgl/J [B] where J is the mass moment of inertia at the center of gravity of the system about the direction perpendicular to the sideframe. For better wheelchair control during wheelchair balance the static stability should be reduced. Measurements of the value for the polar mass moment of inertia for a typical wheelchair + user of m = 90 kg was found to be J = 8.7 kg-m2. In order to decrease the value of the static stability, Equation [B], one can increase J or decrease m and/or l, where l is the distance from the rear axle to the c.g. of the system. It is also shown that balancing a rod in the palm of the hand (inverted pendulum) is a mathematical problem similar to the wheelie balance problem, and a rod of length 1.56 meters is similar to a wheelchair + user system mass of 90 kg. However, balancing a rod is done primarily by using visual perception, whereas wheelie balance involves human joint proprioceptors and visual plus vestibular (inner ear) perception. Thus, a simple test of determining the shortest length of rod one can balance in the palm of the hand (plus measuring handrim force capability and simple reaction time) may indicate if a wheelchair user will find it easy to do a wheelie balance.

Representativeness of regional and global mass-balance measurement networks (Invited)

NASA Astrophysics Data System (ADS)

Cogley, J. G.; Moholdt, G.; Gardner, A. S.

2013-12-01

We showed in a recent publication that regional estimates of glacier mass budgets, obtained by interpolation from in-situ measurements, were markedly more negative than corresponding estimates by satellite gravimetry (GRACE) and satellite altimetry (ICESat) during 2003-2009. Examining the ICESat data in more detail, we found that in-situ records tend to be located in areas where glaciers are thinning more rapidly than as observed in their regional surroundings. Because neither GRACE nor ICESat can provide information for times before 2002-2003, and may not operate without interruption in the future, we explore possible explanations of and remedies for the identified bias in the in-situ network. Sparse spatial sampling, coupled with previously undetected spatial variability of mass balance at scales between the 10-km in-situ scale and the 350-km gravimetric scale, appears to be the leading explanation. Satisfactory remedies are not obvious. Selecting glaciers for in-situ measurement that are more representative will yield only incremental improvements. There appears to be no alternative to mass-balance modelling as a versatile tool for estimation of regional mass balance. However the meteorological data for forcing the surface components of glacier models have coarser resolution than is desirable and are themselves uncertain, especially in the remote regions where much of the glacier ice is found. Measurements of frontal (dynamic) mass changes are still difficult, and modelling of these changes remains underdeveloped in spite of recent advances. Thus research on a broad scale is called for in order to meet the challenge of producing more accurate hindcasts and projections of glacier mass budgets with fine spatial and temporal resolution.

Determination of isoxaflutole (balance) and its metabolites in water using solid phase extraction followed by high-performance liquid chromatography with ultraviolet or mass spectrometry

USGS Publications Warehouse

Lin, Chung-Ho; Lerch, Robert N.; Thurman, E. Michael; Garrett , Harold E.; George, Milon F.

2002-01-01

Balance (isoxaflutole, IXF) belongs to a new family of herbicides referred to as isoxazoles. IXF has a very short soil half-life (<24 h), degrading to a biologically active diketonitrile (DKN) metabolite that is more polar and considerably more stable. Further degradation of the DKN metabolite produces a nonbiologically active benzoic acid (BA) metabolite. Analytical methods using solid phase extraction followed by high-performance liquid chromatography−UV (HPLC-UV) or high-performance liquid chromatography−mass spectrometry (HPLC-MS) were developed for the analysis of IXF and its metabolites in distilled deionized water and ground water samples. To successfully detect and quantify the BA metabolite by HPLC-UV from ground water samples, a sequential elution scheme was necessary. Using HPLC-UV, the mean recoveries from sequential elution of the parent and its two metabolites from fortified ground water samples ranged from 68.6 to 101.4%. For HPLC-MS, solid phase extraction of ground water samples was performed using a polystyrene divinylbenzene polymer resin. The mean HPLC-MS recoveries of the three compounds from ground water samples spiked at 0.05−2 μg/L ranged from 100.9 to 110.3%. The limits of quantitation for HPLC-UV are approximately 150 ng/L for IXF, 100 ng/L for DKN, and 250 ng/L for BA. The limit of quantitation by HPLC-MS is 50 ng/L for each compound. The methods developed in this work can be applied to determine the transport and fate of Balance in the environment.

Determination of isoxaflutole (balance) and its metabolites in water using solid phase extraction followed by high-performance liquid chromatography with ultraviolet or mass spectrometry.

PubMed

Lin, Chung-Ho; Lerch, Robert N; Thurman, E Michael; Garrett, Harold E; George, Milon F

2002-10-09

Balance (isoxaflutole, IXF) belongs to a new family of herbicides referred to as isoxazoles. IXF has a very short soil half-life (<24 h), degrading to a biologically active diketonitrile (DKN) metabolite that is more polar and considerably more stable. Further degradation of the DKN metabolite produces a nonbiologically active benzoic acid (BA) metabolite. Analytical methods using solid phase extraction followed by high-performance liquid chromatography-UV (HPLC-UV) or high-performance liquid chromatography-mass spectrometry (HPLC-MS) were developed for the analysis of IXF and its metabolites in distilled deionized water and ground water samples. To successfully detect and quantify the BA metabolite by HPLC-UV from ground water samples, a sequential elution scheme was necessary. Using HPLC-UV, the mean recoveries from sequential elution of the parent and its two metabolites from fortified ground water samples ranged from 68.6 to 101.4%. For HPLC-MS, solid phase extraction of ground water samples was performed using a polystyrene divinylbenzene polymer resin. The mean HPLC-MS recoveries of the three compounds from ground water samples spiked at 0.05-2 microg/L ranged from 100.9 to 110.3%. The limits of quantitation for HPLC-UV are approximately 150 ng/L for IXF, 100 ng/L for DKN, and 250 ng/L for BA. The limit of quantitation by HPLC-MS is 50 ng/L for each compound. The methods developed in this work can be applied to determine the transport and fate of Balance in the environment.

Calving fluxes and basal melt rates of Antarctic ice shelves.

PubMed

Depoorter, M A; Bamber, J L; Griggs, J A; Lenaerts, J T M; Ligtenberg, S R M; van den Broeke, M R; Moholdt, G

2013-10-03

Iceberg calving has been assumed to be the dominant cause of mass loss for the Antarctic ice sheet, with previous estimates of the calving flux exceeding 2,000 gigatonnes per year. More recently, the importance of melting by the ocean has been demonstrated close to the grounding line and near the calving front. So far, however, no study has reliably quantified the calving flux and the basal mass balance (the balance between accretion and ablation at the ice-shelf base) for the whole of Antarctica. The distribution of fresh water in the Southern Ocean and its partitioning between the liquid and solid phases is therefore poorly constrained. Here we estimate the mass balance components for all ice shelves in Antarctica, using satellite measurements of calving flux and grounding-line flux, modelled ice-shelf snow accumulation rates and a regional scaling that accounts for unsurveyed areas. We obtain a total calving flux of 1,321 ± 144 gigatonnes per year and a total basal mass balance of -1,454 ± 174 gigatonnes per year. This means that about half of the ice-sheet surface mass gain is lost through oceanic erosion before reaching the ice front, and the calving flux is about 34 per cent less than previous estimates derived from iceberg tracking. In addition, the fraction of mass loss due to basal processes varies from about 10 to 90 per cent between ice shelves. We find a significant positive correlation between basal mass loss and surface elevation change for ice shelves experiencing surface lowering and enhanced discharge. We suggest that basal mass loss is a valuable metric for predicting future ice-shelf vulnerability to oceanic forcing.

Application of terrestrial photogrammetry for the mass balance calculation on Montasio Occidentale Glacier (Julian Alps, Italy)

NASA Astrophysics Data System (ADS)

Piermattei, Livia; Carturan, Luca; Calligaro, Simone; Blasone, Giacomo; Guarnieri, Alberto; Tarolli, Paolo; Dalla Fontana, Giancarlo; Vettore, Antonio

2014-05-01

Digital elevation models (DEMs) of glaciated terrain are commonly used to measure changes in geometry and hence infer the mass balance of glaciers. Different tools and methods exist to obtain information about the 3D geometry of terrain. Recent improvements on the quality and performance of digital cameras for close-range photogrammetry, and the development of automatic digital photogrammetric processing makes the 'structure from motion' photogrammetric technique (SfM) competitive for high quality 3D models production, compared to efficient but also expensive and logistically-demanding survey technologies such as airborn and terrestrial laser scanner (TLS). The purpose of this work is to test the SfM approach, using a consumer-grade SLR camera and the low-cost computer vision-based software package Agisoft Photoscan (Agisoft LLC), to monitor the mass balance of Montasio Occidentale glacier, a 0.07km2, low-altitude, debris-covered glacier located in the Eastern Italian Alps. The quality of the 3D models produced by the SfM process has been assessed by comparison with digital terrain models obtained through TLS surveys carried out at the same dates. TLS technique has indeed proved to be very effective in determining the volume change of this glacier in the last years. Our results shows that the photogrammetric approach can produce point cloud densities comparable to those derived from TLS measurements. Furthermore, the horizontal and vertical accuracies are also of the same order of magnitude as for TLS (centimetric to decimetric). The effect of different landscape characteristics (e.g. distance from the camera or terrain gradient) and of different substrata (rock, debris, ice, snow and firn) was also evaluated in terms of SfM reconstruction's accuracy vs. TLS. Given the good results obtained on the Montasio Occidentale glacier, it can be concluded that the terrestrial photogrammetry, with the advantageous features of portability, ease of use and above all low costs, allows to obtain high-resolution DEMs which enable good mass balance estimations on glaciers with similar characteristics.

On the Meaning of Feedback Parameter, Transient Climate Response, and the Greenhouse Effect: Basic Considerations and the Discussion of Uncertainties

NASA Astrophysics Data System (ADS)

Kramm, Gerhard

2010-07-01

In this paper we discuss the meaning of feedback parameter, greenhouse effect and transient climate response usually related to the globally averaged energy balance model of Schneider and Mass. After scrutinizing this model and the corresponding planetary radiation balance we state that (a) the this globally averaged energy balance model is flawed by unsuitable physical considerations, (b) the planetary radiation balance for an Earth in the absence of an atmosphere is fraught by the inappropriate assumption of a uniform surface temperature, the so-called radiative equilibrium temperature of about 255 K, and (c) the effect of the radiative anthropogenic forcing, considered as a perturbation to the natural system, is much smaller than the uncertainty involved in the solution of the model of Schneider and Mass. This uncertainty is mainly related to the empirical constants suggested by various authors and used for predicting the emission of infrared radiation by the Earth's skin. Furthermore, after inserting the absorption of solar radiation by atmospheric constituents and the exchange of sensible and latent heat between the Earth and the atmosphere into the model of Schneider and Mass the surface temperatures become appreciably lesser than the radiative equilibrium temperature. Moreover, neither the model of Schneider and Mass nor the Dines-type two-layer energy balance model for the Earth-atmosphere system, both contain the planetary radiation balance for an Earth in the absence of an atmosphere as an asymptotic solution, do not provide evidence for the existence of the so-called atmospheric greenhouse effect if realistic empirical data are used.

Sampling with poling-based flux balance analysis: optimal versus sub-optimal flux space analysis of Actinobacillus succinogenes.

PubMed

Binns, Michael; de Atauri, Pedro; Vlysidis, Anestis; Cascante, Marta; Theodoropoulos, Constantinos

2015-02-18

Flux balance analysis is traditionally implemented to identify the maximum theoretical flux for some specified reaction and a single distribution of flux values for all the reactions present which achieve this maximum value. However it is well known that the uncertainty in reaction networks due to branches, cycles and experimental errors results in a large number of combinations of internal reaction fluxes which can achieve the same optimal flux value. In this work, we have modified the applied linear objective of flux balance analysis to include a poling penalty function, which pushes each new set of reaction fluxes away from previous solutions generated. Repeated poling-based flux balance analysis generates a sample of different solutions (a characteristic set), which represents all the possible functionality of the reaction network. Compared to existing sampling methods, for the purpose of generating a relatively "small" characteristic set, our new method is shown to obtain a higher coverage than competing methods under most conditions. The influence of the linear objective function on the sampling (the linear bias) constrains optimisation results to a subspace of optimal solutions all producing the same maximal fluxes. Visualisation of reaction fluxes plotted against each other in 2 dimensions with and without the linear bias indicates the existence of correlations between fluxes. This method of sampling is applied to the organism Actinobacillus succinogenes for the production of succinic acid from glycerol. A new method of sampling for the generation of different flux distributions (sets of individual fluxes satisfying constraints on the steady-state mass balances of intermediates) has been developed using a relatively simple modification of flux balance analysis to include a poling penalty function inside the resulting optimisation objective function. This new methodology can achieve a high coverage of the possible flux space and can be used with and without linear bias to show optimal versus sub-optimal solution spaces. Basic analysis of the Actinobacillus succinogenes system using sampling shows that in order to achieve the maximal succinic acid production CO₂ must be taken into the system. Solutions involving release of CO₂ all give sub-optimal succinic acid production.

SeeSway - A free web-based system for analysing and exploring standing balance data.

PubMed

Clark, Ross A; Pua, Yong-Hao

2018-06-01

Computerised posturography can be used to assess standing balance, and can predict poor functional outcomes in many clinical populations. A key limitation is the disparate signal filtering and analysis techniques, with many methods requiring custom computer programs. This paper discusses the creation of a freely available web-based software program, SeeSway (www.rehabtools.org/seesway), which was designed to provide powerful tools for pre-processing, analysing and visualising standing balance data in an easy to use and platform independent website. SeeSway links an interactive web platform with file upload capability to software systems including LabVIEW, Matlab, Python and R to perform the data filtering, analysis and visualisation of standing balance data. Input data can consist of any signal that comprises an anterior-posterior and medial-lateral coordinate trace such as center of pressure or mass displacement. This allows it to be used with systems including criterion reference commercial force platforms and three dimensional motion analysis, smartphones, accelerometers and low-cost technology such as Nintendo Wii Balance Board and Microsoft Kinect. Filtering options include Butterworth, weighted and unweighted moving average, and discrete wavelet transforms. Analysis methods include standard techniques such as path length, amplitude, and root mean square in addition to less common but potentially promising methods such as sample entropy, detrended fluctuation analysis and multiresolution wavelet analysis. These data are visualised using scalograms, which chart the change in frequency content over time, scatterplots and standard line charts. This provides the user with a detailed understanding of their results, and how their different pre-processing and analysis method selections affect their findings. An example of the data analysis techniques is provided in the paper, with graphical representation of how advanced analysis methods can better discriminate between someone with neurological impairment and a healthy control. The goal of SeeSway is to provide a simple yet powerful educational and research tool to explore how standing balance is affected in aging and clinical populations. Copyright © 2018 Elsevier B.V. All rights reserved.

Effects of DanceSport on walking balance and standing balance among the elderly.

PubMed

Sohn, Jeehoon; Park, Sung-Ha; Kim, Sukwon

2018-05-04

Dancesport is a popular activity among older adults who look for fun and fitness in Korea. Studies reported positive sociological and psychological effects of dancesport. But, little studies were performed to evaluate the effects of dancesport on balance performances. The objective of the present study was to evaluate the effects of dancesport for 15 weeks on walking balance and standing balance of older adults. Older adults regularly participated in the dancesport program 3 times a week for 15 weeks. The program included Rumba, Cha-cha-cha, and Jive. They exercised the prescribed dancesport at intermediate level for 50-60 mins for each time. A total 22 reflective markers were placed on the anatomical landmarks and 8 cameras were used to measure 3-D positions of participants. Also, center of pressure (COP) data were measured to analyze standing balance using a ground reaction board at 1200 Hz for 30 seconds. One-way analysis of variance (ANOVA) was performed to test the effects of 15 weeks of dancesport on walking balance and standing balance. The results suggested that, after 15 weeks of dancesport participation, older adults' walking balance (48.3 ± 20.3 cm2 vs 38.2 ± 18.2 cm2) and standing balance (COP area: 189.4 ± 85.4 mm2 vs 103.5 ± 55.4mm2, COP distance: 84.2 ± 34.4 cm vs 76.5 ± 21.4 cm) were significantly improved. Performing dancesport would require moving center of mass rapidly and frequently while maintaining posture. This may result in improving walking balance and standing balance in the present study. The study concluded that dancesport would be an effective exercise method in enhancing postural stability of older adults.

Mass, Energy, Entropy and Exergy Rate Balance in a Ranque-Hilsh Vortex Tube

ERIC Educational Resources Information Center

Carrascal Lecumberri, Edorta; Sala Lizarraga, José María

2013-01-01

The objective of this paper is to present a laboratory program designed for the Thermodynamics course offered in the Department of Thermal Engineering at the University of the Basque Country. With reference to one of the examples given in the textbook by Moran, Shapiro, Boettner and Bailey (2012), the balances of mass, energy, entropy and exergy…

Balance of dark and luminous mass in rotating galaxies.

PubMed

McGaugh, Stacy S

2005-10-21

A fine balance between dark and baryonic mass is observed in spiral galaxies. As the contribution of the baryons to the total rotation velocity increases, the contribution of the dark matter decreases by a compensating amount. This poses a fine-tuning problem for galaxy formation models, and may point to new physics for dark matter particles or even a modification of gravity.

Implications of sodium mass balance for interpreting the calcium cycle of a forested ecosystem

Treesearch

Scott W. Bailey; Donald C. Buso; Gene E. Likens

2003-01-01

Disturbance of forest ecosystems, such as that caused by harvesting or acid deposition, is thought to alter the ability of the ecosystem to retain nutrients. Although many watershed studies have suggested depletion of available calcium (Ca) pools, interpretation of ecosystem Ca mass balance has been limited by the difficulty in obtaining mineral weathering flux...

Water and sodium balances and their relation to body mass changes in microgravity.

PubMed

Drummer, C; Hesse, C; Baisch, F; Norsk, P; Elmann-Larsen, B; Gerzer, R; Heer, M

2000-12-01

Since the very beginning of space physiology research, the deficit in body mass that is often observed after landing has always been interpreted as an indication of the absolute fluid loss early during space missions. However, in contrast to central hypervolemic conditions on Earth, the acute shift of blood volume from the legs to the upper part of the body in astronauts entering microgravity (microG) has neither stimulated diuresis and natriuresis nor resulted in negative water-and sodium-balances. We therefore examined the kinetics of body mass changes in astronauts (n = 3) during their several weeks aboard the space station MIR. A continuous diet monitoring was performed during the first mission (EuroMIR94, 30 days). The second mission (MIR97, 19 days) comprised a 15-day metabolic ward period (including predefined constant energy and sodium intake). Water and sodium balances were calculated and the kinetic of changes in basal concentrations of fluid-balance-related hormones during flight were determined. The data suggest firstly that loss of body mass during space flight is rather a consequence of hypocaloric nutrition. Secondly, microG provokes a sodium retaining hormonal status and may lead to sodium storage without an accompanying fluid retention.

Micrometeorological Mass Balance Measurements of Greenhouse Gas Emissions from Composting Green-waste

NASA Astrophysics Data System (ADS)

Kent, E. R.; Bailey, S.; Stephens, J.; Horwath, W. R.; Paw U, K.

2013-12-01

Managed decomposition of organic materials is increasingly being used as an alternative waste management option and the resulting compost can be used as a fertilizer and soil amendment in home gardens and agriculture. An additional benefit is the avoidance of methane emissions associated with anaerobic decomposition in landfills. Greenhouse gases are still emitted during the composting process, but few studies have measured emissions from a full-scale windrow of composting green-waste. This study uses a micrometeorological mass balance technique (upwind and downwind vertical profile measurements of trace gas concentrations and wind velocity) to calculate emissions of carbon dioxide, methane, and nitrous oxide from a pile of composting green-waste during the dry season in Northern California. The expected source pattern was observed in measured upwind-downwind concentration differences of all three gases averaged over the study period despite substantial noise seen in the half-hourly emission calculations. Sources of uncertainty are investigated and temporal patterns analyzed. An in-situ zero-source test was conducted to examine the mass balance technique when the source of emissions was removed. Results from the micrometeorological mass balance measurements are compared with measurements taken using the more common open chamber technique.

One session of high-intensity interval training (HIIT) every 5 days, improves muscle power but not static balance in lifelong sedentary ageing men

PubMed Central

Sculthorpe, Nicholas F.; Herbert, Peter; Grace, Fergal

2017-01-01

Abstract Background: Declining muscle power during advancing age predicts falls and loss of independence. High-intensity interval training (HIIT) may improve muscle power, but remains largely unstudied in ageing participants. Methods: This randomized controlled trial (RCT) investigated the efficacy of a low-frequency HIIT (LfHIIT) intervention on peak muscle power (peak power output [PPO]), body composition, and balance in lifelong sedentary but otherwise healthy males. Methods: Thirty-three lifelong sedentary ageing men were randomly assigned to either intervention (INT; n = 22, age 62.3 ± 4.1 years) or control (n = 11, age 61.6 ± 5.0 years) who were both assessed at 3 distinct measurement points (phase A), after 6 weeks of conditioning exercise (phase B), and after 6 weeks of HIIT once every 5 days in INT (phase C), where control remained inactive throughout the study. Results: Static balance remained unaffected, and both absolute and relative PPO were not different between groups at phases A or B, but increased significantly in INT after LfHIIT (P < 0.01). Lean body mass displayed a significant interaction (P < 0.01) due to an increase in INT between phases B and C (P < 0.05). Conclusions: 6 weeks of LfHIIT exercise feasible and effective method to induce clinically relevant improvements in absolute and relative PPO, but does not improve static balance in sedentary ageing men. PMID:28178145

Regional Climate Modeling over the Glaciated Regions of the Canadian High Arctic

NASA Astrophysics Data System (ADS)

Gready, Benjamin P.

The Canadian Arctic Islands (CAI) contain the largest concentration of terrestrial ice outside of the continental ice sheets. Mass loss from this region has recently increased sharply due to above average summer temperatures. Thus, increasing the understanding of the mechanisms responsible for mass loss from this region is critical. Previously, Regional Climate Models (RCMs) have been utilized to estimate climatic balance over Greenland and Antarctica. This method offers the opportunity to study a full suite of climatic variables over extensive spatially distributed grids. However, there are doubts of the applicability of such models to the CAI, given the relatively complex topography of the CAI. To test RCMs in the CAI, the polar version of the regional climate model MM5 was run at high resolution over Devon Ice Cap. At low altitudes, residuals (computed through comparisons with in situ measurements) in the net radiation budget were driven primarily by residuals in net shortwave (NSW) radiation. Residuals in NSW are largely due to inaccuracies in modeled cloud cover and modeled albedo. Albedo on glaciers and ice sheets is oversimplified in Polar MM5 and its successor, the Polar version of the Weather Research and Forecast model (Polar WRF), and is an obvious place for model improvement. Subsequently, an inline parameterization of albedo for Polar WRF was developed as a function of the depth, temperature and age of snow. The parameterization was able to reproduce elevation gradients of seasonal mean albedo derived from satellite albedo measurements (MODIS MOD10A1 daily albedo), on the western slope of the Greenland Ice Sheet for three years. Feedbacks between modelled albedo and modelled surface energy budget components were identified. The shortwave radiation flux feeds back positively with changes to albedo, whereas the longwave, turbulent and ground energy fluxes all feed back negatively, with a maximum combined magnitude of two thirds of the shortwave feedback magnitude. These strong feedbacks demonstrate that an accurate albedo parameterization must be run inline within an RCM, to accurately quantify the net surface energy budget of an ice sheet. Finally, Polar WRF, with the improved albedo parameterization, was used to simulate climatic balance over the Queen Elizabeth Islands for the summers of 2001 to 2008. Climatic balance was derived from the output using energy balance and temperature index melt models. Regional mass balance was calculated by combining climatic balance with estimates of iceberg discharge. Mass balance estimates from the model agreed, within the bounds of uncertainty, with estimates from previous studies, thus supporting the assertion that mass loss from the QEI accelerated during the first decade of the 21st century. Melt rates on the seven major icecaps of the QEI became more correlated to one another during the period 2001-2008. However, precipitation became less correlated from 2003-2008. These observations are coincident with dramatic increases in melt on all of the ice caps, and it is speculated that both are caused by decreases in the scale of disturbances delivering precipitation to the region over time.

Gap-Balancing versus Measured Resection Technique in Total Knee Arthroplasty: A Comparison Study.

PubMed

Churchill, Jessica L; Khlopas, Anton; Sultan, Assem A; Harwin, Steven F; Mont, Michael A

2018-01-01

Proper femoral component alignment in the axial plane during total knee arthroplasty (TKA) depends on accurate bone cuts and soft tissue balancing. Two methods that are used to achieve this are "measured resection" and "gap balancing." However, a controversy exists as to which method is more accurate and leads to better outcomes. Therefore, the purpose of this study was to evaluate: (1) implant survivorship, (2) patient outcomes, (3) complications, and (4) radiographic analysis comparing patients who underwent TKA with either gap-balancing or measured resection techniques. A total of 214 consecutive patients (221 knees) underwent primary TKA by a single surgeon between 2011 and 2012. Component alignment was achieved by using measured resection in 116 knees and gap balancing was used in 105 knees. The patients had a mean age of 66 years (range, 44-86 years) and a mean body mass index of 32 kg/m 2 (range, 22-52 kg/m 2 ). Patient range-of-motion (ROM) and Knee Society (KS) function and pain scores, and radiographic assessment, were assessed preoperatively and postoperatively at ∼6 weeks, 3 months, 1 year, and then annually. The mean follow-up time was 3 years. A Kaplan-Meier's analysis was performed to calculate the survivorship. The aseptic survivorship was 98% in both the measured resection and gap-balancing groups. The mean ROM was not significantly different between the measured resection and gap-balancing groups (123 vs. 123 degrees, p  = 0.990). There were no significant differences between the two groups in terms of the KS function scores (86 vs. 85 points, p  = 0.829) or the KS pain scores (93 vs. 92 points, p  = 0.425). Otherwise, the radiographic evaluation at latest follow-up did not demonstrate any evidence of progressive radiolucencies or loosening, of any prosthesis. The results of this study found that at a mean follow-up of 3 years, both the measured resection and gap-balancing techniques achieved excellent survivorship and postoperative outcomes. This demonstrates that both methods can be used to achieve accurate femoral component alignment with similar short-term outcomes. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Structural redundancy of data from wastewater treatment systems. Determination of individual balance equations.

PubMed

Spindler, A

2014-06-15

Although data reconciliation is intensely applied in process engineering, almost none of its powerful methods are employed for validation of operational data from wastewater treatment plants. This is partly due to some prerequisites that are difficult to meet including steady state, known variances of process variables and absence of gross errors. However, an algorithm can be derived from the classical approaches to data reconciliation that allows to find a comprehensive set of equations describing redundancy in the data when measured and unmeasured variables (flows and concentrations) are defined. This is a precondition for methods of data validation based on individual mass balances such as CUSUM charts. The procedure can also be applied to verify the necessity of existing or additional measurements with respect to the improvement of the data's redundancy. Results are given for a large wastewater treatment plant. The introduction aims at establishing a link between methods known from data reconciliation in process engineering and their application in wastewater treatment. Copyright © 2014 Elsevier Ltd. All rights reserved.

Capacity of biochar application to maintain energy crop productivity: soil chemistry, sorghum growth, and runoff water quality effects.

PubMed

Schnell, Ronnie W; Vietor, Donald M; Provin, Tony L; Munster, Clyde L; Capareda, Sergio

2012-01-01

Pyrolysis of crop biomass generates a by-product, biochar, which can be recycled to sustain nutrient and organic C concentrations in biomass production fields. We evaluated effects of biochar rate and application method on soil properties, nutrient balance, biomass production, and water quality. Three replications of eight sorghum [ (L.) Moench] treatments were installed in box lysimeters under greenhouse conditions. Treatments comprised increasing rates (0, 1.5, and 3.0 Mg ha) of topdressed or incorporated biochar supplemented with N fertilizer or N, P, and K fertilizer. Simulated rain was applied at 21 and 34 d after planting, and mass runoff loss of N, P, and K was measured. A mass balance of total N, P, and K was performed after 45 d. Returning 3.0 Mg ha of biochar did not affect sorghum biomass, soil total, or Mehlich-3-extractable nutrients compared to control soil. Yet, biochar contributed to increased concentration of dissolved reactive phosphorus (DRP) and mass loss of total phosphorus (TP) in simulated runoff, especially if topdressed. It was estimated that up to 20% of TP in topdressed biochar was lost in surface runoff after two rain events. Poor recovery of nutrients during pyrolysis and excessive runoff loss of nutrients for topdressed biochar, especially K, resulted in negative nutrient balances. Efforts to conserve nutrients during pyrolysis and incorporation of biochar at rates derived from annual biomass yields will be necessary for biochar use in sustainable energy crop production. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.