A sensitivity study of the WRF model in offshore wind modeling over the Baltic Sea

Accurate wind modeling is important for wind resources assessment and wind power forecasting. To improve the WRF model configuration for the offshore wind modeling over the Baltic Sea, this study performed a sensitivity study of the WRF model to multiple model configurations, including domain setup,grid resolution, sea surface temperature, land surface data, and atmosphere-wave coupling. The simulated offshore wind was evaluated against LiDAR observations under different wind directions, atmospheric stabilities, and sea status. Generally, the simulated wind profiles matched observations, despite systematic underestimations. Strengthening the forcing from the reanalysis data through reducing the number of nested domains played the largest role in improving wind modeling. Atmosphere-wave coupling further improved the simulated wind, especially under the growing and mature sea conditions.Increasing the vertical resolution, and updating the sea surface temperature and the land surface information only had a slight impact, mainly visible during very stable conditions. Increasing the horizontal resolution also only had a slight impact, most visible during unstable conditions. Our study can help to improve the wind resources assessment and wind power forecasting over the Baltic Sea.

Snow and sea ice thermodynamics in the Arctic:Model validation and sensitivity study against SHEBA data

Evolution of the Arctic sea ice and its snow cover during the SHEBA year were simulated by applying a high-resolution thermodynamic snow/ice model （HIGHTSI）. Attention was paid to the impact of albedo on snow and sea ice mass balance, effect of snow on total ice mass balance, and the model vertical resolution. The SHEBA annual simulation was made applying the best possible external forcing data set created by the Sea Ice Model Intercomparison Project. The HIGHTSI control run reasonably reproduced the observed snow and ice thickness. A number of albedo schemes were incorporated into HIGHTSI to study the feedback processes between the albedo and snow and ice thickness. The snow thickness turned out to be an essential variable in the albedo parameterization. Albedo schemes dependent on the surface temperature were liable to excessive positive feedback effects generated by errors in the modelled surface temperature. The superimposed ice formation should be taken into account for the annual Arctic sea ice mass balance.

A Sensitivity Study on Parameterization Scheme of Snow Internal and Interfacial Processes in Snow Model

In order to develop a seasonal snow model of land surface process as accurately as possible for climatic study. it is necessary to fully understand the effects of important snow internal processes and interaction with air and to get an insight into influence of several relevant parameterization schemes with parameters' uncertainty to some degree. Using the snow model (SAST) developed by first author and other one and some useful field observation data, this paper has conducted a series of sensitivity studies on the parameterization schemes. They are relative to compaction process, snow thermal conduction, methodology of layering snow pack and to key parameters such as snow albedo, water holding capacity. Then, based on the results from the sensitivity studies, some useful conclusions for snow cover model improvement are obtained from the analysis of the results.

A Sensitivity Study of IAP AGCM to Radiation Changes: Climate Simulation of 125kyr and 115kyr before Present

The IAP AGCM was used to simulate the climate of 125kyr and 115kyr before present. We analysed the results and then studied the sensitivity of the model to the changes of radiation distribution induced by orbital parameter changes. The reasonability of the results was also discussed.

A Sensitivity Study of Single Column Model

A single column model (SCM) is constructed by extracting the physical subroutines from the NCAR Community Climate Model version 1 (CCM1).Simulated data are generated by CCM1 and used to validate the SCM and to study the sensitivity of the SCM to errors in its input data.It is found that the SCM temperature predictions are moderately sensitive to errors in the input horizontal temperature flux convergence and moisture flux convergence.Two types of error are concerned in this study,random errors due to insufficient data resolution,and errors due to insufficient data area coverage.While the first type of error can be reduced by filtering and/or increasing the data resolution,it is shown that the second type of error can be reduced by enlarging the data area coverage and using a suitable method to compute the input flux convergence terms.

Studies on the Relation between the Composition of Thermal Sensitive MnZn Ferrite and Curie Temperature

Thermal sensitive MnZn ferrite is a kind of soft magnetic ferrite material with lower Curie temperature (Tc) and can be used to make many kinds of magnetic thermal sensitive sensors with high sensitivity. In this paper, the relation between the composition of thermal sensitive ferrite and TC was studied. It was found that TC changes linearly with ZnO extent when the content of Fe2O3 is fixed. Based on lots of experiments, an experimential formula to determine was given out.

Global Analysis of a Flexible Riser

The mechanical performance of a flexible riser is more outstanding than other risers in violent environmental conditions. Based on the lumped mass method, a steep wave flexible riser configuration attached to a Floating Production Storage and Offioading （FPSO） has been applied to a global analysis in order to acquire the static and dynamic behavior of the flexible riser. The riser was divided into a series of straight massless line segments with a node at each end. Only the axial and torsional properties of the line were modeled, while the mass, weight, and buoyancy were all lumped to the nodes. Four different buoyancy module lengths have been made to demonstrate the importance of mode selection, so as to confirm the optimum buoyancy module length. The results in the sensitivity study show that the flexible riser is not very sensitive to the ocean current, and the buoyancy module can reduce the Von Mises stress and improve the mechanical performance of the flexible riser. Shorter buoyancy module length can reduce the riser effective tension in a specific range of the buoyancy module length when other parameters are constant, but it can also increase the maximum curvature of the riser. As a result, all kinds of the riser performances should be taken into account in order to select the most appropriate buoyancy module length.

Enhancing recovery and sensitivity studies in an unconventional tight gas condensate reservoir

The recovery factor from tight gas reservoirs is typically less than 15%, even with multistage hydrauhc tractunng stimulation. Such low recovery is exacerbated in tight gas condensate reservoirs, where the depletion of gas leaves the valuable condensate behind. In this paper, three enhanced gas recovery （EGR） methods including produced gas injection, CO2 injection and water injection are investigated to increase the well productivity for a tight gas condensate reservoir in the Montney Formation, Canada. The production performance of the three EGR methods is compared and their economic feasibility is evaluated. Sensitivity analysis of the key factors such as primary production duration, bottom-hole pressures, and fracture conductivity is conducted and their effects on the well production performance are analyzed. Results show that, compared with the simple depletion method, both the cumulative gas and condensate production increase with fluids injected. Produced gas injection leads to both a higher gas and condensate production compared with those of the CO2 injection, while waterflooding suffers from injection difficulty and the corresponding low sweep efficiency. Meanwhile, the injection cost is lower for the produced gas injection due to the on-site available gas source and minimal transport costs, gaining more economic benefits than the other EGR methods.

Observations and Modeling of Incoming Longwave Radiation to Snow Beneath Forest Canopies in the West Tianshan Mountains, China

Forest canopy reduces shortwave radiation and increases the incoming longwave radiation to snowpacks beneath forest canopies. Furthermore, the effect of forest canopy may be changed by complex topography. In this paper, we measured and simulated the incoming longwave radiation to snow beneath forest at different canopy openness in the west Tianshan Mountains, China(43°16'N, 84°24'E) during spring 2013. A sensitivity study was conducted to explore the way that terrain influenced the incoming longwave radiation to snow beneath forest canopies. In the simulation model, measurement datasets, including air temperature, incoming shortwave radiation above canopy, and longwave radiation enhanced by adjacent terrain, were applied to calculate the incoming longwave radiation to snow beneath forest canopy. The simulation results were consistent with the measurements on hourly scale and daily scale. The effect of longwave radiation enhanced by terrain was important than that of shortwave radiation above forest canopy with different openness except the 20% canopy openness. The longwave radiation enhanced due to adjacent terrain increases with the slope increase and temperature rise. When air temperature(or slope) is relatively low, thelongwave radiation enhanced by adjacent terrain is not sensitive to slope(or air temperature), but the sensitivity increases with the decrease of snow cover area on sunny slope. The effect of longwave radiation is especially sensitive when the snow cover on sunny slope melts completely. The effect of incoming shortwave radiation reflected by adjacent terrain on incoming longwave radiation to snow beneath forest canopies is more slight than that of the enhanced longwave radiation.

Remarkably different results between two studies from North America on genomic mutations and sensitivity to DNA demethylating agents for myelodysplastic syndromes

Sekeres et al. （1） conducted a multicenter randomized, controlled trial to compare whether azacitidine-based combinations with lenalidomide or vorinostat produce superior overall response rates to azacitidine in the treatment of myelodysplastic syndromes （MDS）. In that trial, 224 patients with higher-risk MDS and 53 with chronic myelomonocytic leukemia （CMML） were enrolled and randomly assigned to the ＂azacitidine＂ group, ＂azacitidine plus lenalidomide＂ group or ＂azacitidine plus vorinostat＂ group. The researchers found that patients with MDS treated with azacitidine-based combinations had similar response rate to azacitidine monotherapy. Using genomic mutation analysis, they found that the overall response rate to azacitidine-based treatment was higher for patients with mutations in DNMT3A and lower for those with mutations in SRSF2. Whereas in another study, Welch et al. enrolled 26 patients with MDS and 90 with acute myeloid leukemia （AML） who were treated with decitabine, and they found that patients with TP53 mutations had a higher response rate, but not those with DNMT3A mutations （2）. We propose that this big discrepancy in the conclusions between the two studies might have been caused by the presence of many co-interacting factors, e.g. study aims, DNA demethylating agents, treatment protocols, and patient sources.

An Efficient Scrambled Estimator of Population Mean of Quantitative Sensitive Variable Using General Linear Transformation of Non-sensitive Auxiliary Variable

In the present paper,we propose an efficient scrambled estimator of population mean of quantitative sensitive study variable,using general linear transformation of nonsensitive auxiliary variable.Efficiency comparisons with the existing estimators have been carried out both theoretically and numerically.It has been found that our optimal scrambled estimator is always more efficient than most of the existing scrambled estimators and also it is more efficient than few other scrambled estimators under some conditions.

Creep-fatigue lives prediction and sensitivity study of 316H at 550 ℃

In Volume 2/3 of R5 ＂An assessment procedure for the high temperature response of structures＂, the strain based ductility exhaustion method is suggested to calculate the creep damage of stress concentration region, which involves description of creep dwell initial stress, stress drop and creep ductility. Considering lots of uncertainty existed in these assessment, some sensitivity analysis is required in R5 procedure to ensure the conservatism of assessment results. In this paper, laboratory creep-fatigue test data of 316H at 550 ℃ with different loading conditions are selected as a special case to investigate whether the basic R5 approach is conservative, and the different material data combinations of cyclic stress-strain, creep deformation and creep ductility are used to identify those significant parameters affecting the assessment results. The analytical results indicate that the creep deformation model and creep ductility data are more significant to the results comparing with cyclic stress-strain data. If the upper bound of creep deformation law and lower bound of creep ductility data are used to predict their creep-fatigue lives, the degree of conservatism can be as large as a factor of -300, but if the modified creep deformation model and cast specific ductility data are used, very well prediction results can be gained within a factor of ±2.0 although there is slight non-conservatism.

Study of the CKM angleγsensitivity using flavor untagged B_(s)^(0)→D^(+)^(0)Ф decays

A sensitivity study on the measurement of the CKM angle γ from B_(s)^(0)→D^(+)^(0)Ф decays is conducted us-ing the D-meson reconstructed in the quasi flavour-specific modes Kπ,K3π,and Kππ^(0),as well as CP-eigenstate modes KK and m,where the notation DO corresponds toa D0 or D0 meson.The LHCb experiment is presented as a use case.A statistical uncertainty of approximately 8°-19°can be achieved with the pp collision data collcted in the LHCb experiment from 2011 to 2018.The sensitivity to r should be of the order 3°-8°after accumulating 23 fb^(-1) of pp collision data by 2025,whereas it is expected to improve further by 300 fb^(-1) by the second half of the 2030 decade.The accuracy is dependent on the strong parameters r and og,which together with ydescribe the interfer-ence between the leading ampliudes of the B_(s)^(0)→D^(+)^(0)Ф decays.

Preliminary sensitivity study on an life cycle assessment(LCA)tool via assessing a hybrid timber building

In order to address concerns related to global warming and increased atmospheric carbon content,the life cycle assessment(LCA)tool has demonstrated usefulness in the building and construction sector.The LCA is used to evaluate environmental impacts concerning all stages of the building process from“cradle”to“grave”.The LCA helps promote sustainable development by considering environmental indicators such as stratospheric ozone depletion,eutrophication,global warming potential,and many more.It is of an interest to know the degree of impact on a given environ-mental indicator if an input is changed in terms of the type or amount of the materials used.The LCA software Athena IE4B was employed to analyze data of a selected timber building.This study was aimed at evaluating the sensitivity of LCA analysis on a hybrid timber building,which was done via two case studies.Case 1 focused on changes in the volume of wood materials,meanwhile Case 2 focused on simultaneous changes in the volume of materials for wood,steel,and concrete.In Case 1,it was observed increasing wood materials increased environmental indicators,with stratospheric ozone depletion being the most sensitive and global warming potential as the least sensitive.Case 2 discovered that proportionally increasing wood materials in relation to steel and concrete materials decreased environmental indicators,with eutrophication being the most sensitive and stratospheric ozone depletion as the least sensitive.This study helped support the feasibility of using Athena IE4B for LCA analysis in the initial assessment of a building.