This work presents the results of the exact computation of (180)<sup>3</sup> = 5,832,000 third-order mixed sensitivities of the leakage response of a polyethylene-reflected plutonium (PERP) experimental be...This work presents the results of the exact computation of (180)<sup>3</sup> = 5,832,000 third-order mixed sensitivities of the leakage response of a polyethylene-reflected plutonium (PERP) experimental benchmark with respect to the benchmark’s 180 microscopic total cross sections. This computation was made possible by applying the Third-Order Adjoint Sensitivity Analysis Methodology developed by Cacuci. The numerical results obtained in this work revealed that many of the 3<sup>rd</sup>-order sensitivities are significantly larger than their corresponding 1<sup>st</sup>- and 2<sup>nd</sup>-order ones, which is contrary to the widely held belief that higher-order sensitivities are all much smaller and hence less important than the first-order ones, for reactor physics systems. In particular, the largest 3<sup>rd</sup>-order relative sensitivity is the mixed sensitivity <img src="Edit_754b8437-dfdf-487d-af68-c78c637e6d4e.png" width="180" height="24" alt="" />of the PERP leakage response with respect to the lowest energy-group (30) total cross sections of <sup>1</sup>H (“isotope 6”) and <sup>239</sup>Pu (“isotope 1”). These two isotopes are shown in this work to be the two most important parameters affecting the PERP benchmark’s leakage response. By comparison, the largest 1<sup>st</sup>-order sensitivity is that of the PERP leakage response with respect to the lowest energy-group total cross section of isotope <sup>1</sup>H, having the value <img src="Edit_a5cfcc11-6a99-41ee-b844-a5ee84b454b3.png" width="100" height="24" alt="" />, while the largest 2<sup>nd</sup>-order sensitivity is <img src="Edit_05166a2b-97f7-43f1-98ff-b21368c00228.png" width="120" height="22" alt="" />. The 3<sup>rd</sup>-order sensitivity analysis presented in this work is the first ever such analysis in the field of reactor physics. The consequences of the results presented in this work on the uncertainty analysis of the PERP benchmark’s leakage response will be presented in a subsequent work.展开更多
This work presents the “Second-Order Comprehensive Adjoint Sensitivity Analysis Methodology (2<sup>nd</sup>-CASAM)” for the efficient and exact computation of 1<sup>st</sup>- and 2<sup>...This work presents the “Second-Order Comprehensive Adjoint Sensitivity Analysis Methodology (2<sup>nd</sup>-CASAM)” for the efficient and exact computation of 1<sup>st</sup>- and 2<sup>nd</sup>-order response sensitivities to uncertain parameters and domain boundaries of linear systems. The model’s response (<em>i.e.</em>, model result of interest) is a generic nonlinear function of the model’s forward and adjoint state functions, and also depends on the imprecisely known boundaries and model parameters. In the practically important particular case when the response is a scalar-valued functional of the forward and adjoint state functions characterizing a model comprising N parameters, the 2<sup>nd</sup>-CASAM requires a single large-scale computation using the First-Level Adjoint Sensitivity System (1<sup>st</sup>-LASS) for obtaining all of the first-order response sensitivities, and at most N large-scale computations using the Second-Level Adjoint Sensitivity System (2<sup>nd</sup>-LASS) for obtaining exactly all of the second-order response sensitivities. In contradistinction, forward other methods would require (<em>N</em>2/2 + 3 <em>N</em>/2) large-scale computations for obtaining all of the first- and second-order sensitivities. This work also shows that constructing and solving the 2<sup>nd</sup>-LASS requires very little additional effort beyond the construction of the 1<sup>st</sup>-LASS needed for computing the first-order sensitivities. Solving the equations underlying the 1<sup>st</sup>-LASS and 2<sup>nd</sup>-LASS requires the same computational solvers as needed for solving (<em>i.e.</em>, “inverting”) either the forward or the adjoint linear operators underlying the initial model. Therefore, the same computer software and “solvers” used for solving the original system of equations can also be used for solving the 1<sup>st</sup>-LASS and the 2<sup>nd</sup>-LASS. Since neither the 1<sup>st</sup>-LASS nor the 2<sup>nd</sup>-LASS involves any differentials of the operators underlying the original system, the 1<sup>st</sup>-LASS is designated as a “<u>first-level</u>” (as opposed to a “first-order”) adjoint sensitivity system, while the 2<sup>nd</sup>-LASS is designated as a “<u>second-level</u>” (rather than a “second-order”) adjoint sensitivity system. Mixed second-order response sensitivities involving boundary parameters may arise from all source terms of the 2<sup>nd</sup>-LASS that involve the imprecisely known boundary parameters. Notably, the 2<sup>nd</sup>-LASS encompasses an automatic, inherent, and independent “solution verification” mechanism of the correctness and accuracy of the 2nd-level adjoint functions needed for the efficient and exact computation of the second-order sensitivities.展开更多
The parameter sensitivities affecting the flutter speed of the NREL （National Renewable Energy Laboratory） 5-MW baseline HAWT （horizontal axis wind turbine） blades are analyzed. An aeroelastic model, which compris...The parameter sensitivities affecting the flutter speed of the NREL （National Renewable Energy Laboratory） 5-MW baseline HAWT （horizontal axis wind turbine） blades are analyzed. An aeroelastic model, which comprises an aerodynamic part to calculate the aerodynamic loads and a structural part to determine the structural dynamic responses, is established to describe the classical flutter of the blades. For the aerodynamic part, Theodorsen unsteady aerodynamics model is used. For the structural part, Lagrange’s equation is employed. The flutter speed is determined by introducing “V–g” method to the aeroelastic model, which converts the issue of classical flutter speed determination into an eigenvalue problem. Furthermore, the time domain aeroelastic response of the wind turbine blade section is obtained with employing Runge-Kutta method. The results show that four cases （i.e., reducing the blade torsional stiffness, moving the center of gravity or the elastic axis towards the trailing edge of the section, and placing the turbine in high air density area） will decrease the flutter speed. Therefore, the judicious selection of the four parameters （the torsional stiffness, the chordwise position of the center of gravity, the elastic axis position and air density） can increase the relative inflow speed at the blade section associated with the onset of flutter.展开更多
Due to global warming, glaciers on the Tibetan Plateau(TP) are experiencing widespread shrinkage; however, the mechanisms controlling glacier variations across the TP are still rather unclear, especially on the northe...Due to global warming, glaciers on the Tibetan Plateau(TP) are experiencing widespread shrinkage; however, the mechanisms controlling glacier variations across the TP are still rather unclear, especially on the northeastern TP. In this study, a physically based, distributed surface-energy and mass-balance model was used to simulate glacier mass balance forced by meteorological data. The model was applied to Laohugou No. 12 Glacier, western Qilian Mountains, China, during2010~2012. The simulated albedo and mass balance were validated and calibrated by in situ measurements. The simulated annual glacier-wide mass balances were-385 mm water equivalent(w.e.) in 2010/2011 and-232 mm w.e. in 2011/2012,respectively. The mean equilibrium-line altitude(ELA) was 5,015 m a.s.l., during 2010~2012, which ascended by 215 m compared to that in the 1970 s. The mean accumulation area ratio(AAR) was 39% during the two years. Climatic-sensitivity experiments indicated that the change of glacier mass balance resulting from a 1.5 °C increase in air temperature could be offset by a 30% increase in annual precipitation. The glacier mass balance varied linearly with precipitation, at a rate of130 mm w.e. per 10% change in total precipitation.展开更多
A global forecast model is used to examine various sensitivities of numerical predictions of three extreme winter storms that occurred near the eastern continental margin of North America: the Ohio Valley blizzard of ...A global forecast model is used to examine various sensitivities of numerical predictions of three extreme winter storms that occurred near the eastern continental margin of North America: the Ohio Valley blizzard of January 1978, the New England blizzard of February 1978, and the Mid-Atlantic cyclone of February 1979. While medium-resolution simulations capture much of the intensification, the forecasts of the precise timing and intensity levels suffer from various degrees of error. The coastal cyclones show a 5-10 hPa dependence on the western North Atlantic sea surface temperature, which is varied within a range (± 2.5℃) compatible with interannual fluctuations. The associated vertical velocities and precipitation rates show proportionately stronger dependences on the ocean temperature perturbations. The Ohio Valley blizzard, which intensified along a track 700-800 km from the coast, shows little sensitivity to ocean temperature. The effect of a shift of - 10?latitude in the position of the snow boundary is negligible in each case. The forecasts depend strongly on the model resolution, and the coarse-resolution forecasts are consistently inferior to the medium-resolution forecasts. Studies of the corresponding sensitivities of extreme cyclonic events over eastern Asia are encouraged in order to identify characteristics that are common to numerical forecasts for the two regions.展开更多
The etiological agent of severe acute respiratory syndrome(SARS) was identified as a new coronavirus,termed SARS-CoV. Establishment of an efficient and sensitive diagnostic system of SARS-CoV genetic materials is cruc...The etiological agent of severe acute respiratory syndrome(SARS) was identified as a new coronavirus,termed SARS-CoV. Establishment of an efficient and sensitive diagnostic system of SARS-CoV genetic materials is crucial for SARS control. In this study,we quantified SARS-CoV mRNAs in both infected cell culture lysate and in supernatant by using Real-time quantitative revere transcription-PCR based on EvaGreenTM dye and Taqman-MGB probes. For extensive evaluation of sensitivities and specificities,13 pairs of primers and 4 probes were designed based on different genes of SARS-CoV. Glyceraldehydes-3-phosphate dehydrogenase(GAPDH) was selected as the internal control gene. Results showed that S-gene-specific PCR was the most sensitive for detection,but because of its sequence variability in the different viral strains,primers and a probe based on the N gene were suitable substitutions. Meanwhile,we found the mRNA concentrations in cell culture lysates were much higher than in cell supernatant and facilited more sensitive detection of the SARS-CoV.展开更多
The accurate diagnosis of tuberculosis caused by members of the Mycobacterium tuberculosis complex (MTBC) has remained a major challenge in clinical laboratories world-wide. Several studies have evaluated the use of h...The accurate diagnosis of tuberculosis caused by members of the Mycobacterium tuberculosis complex (MTBC) has remained a major challenge in clinical laboratories world-wide. Several studies have evaluated the use of highly specific in-house PCR assays targeting the IS6110, hupB, rpoB, oxyR, and IS1081 genes in the detection of MTBC species with reports on variable sensitivities depending on the geographical sourcing of isolates. In the present investigations, we evaluated the sensitivities of these PCR assays on 125 MTBC cultured isolates from five (West, Centre, Littoral, North West and South West) of the ten regions of Cameroon. Of this number, 124 (99.2%), 117 (93.6%), 123 (99.1%), 119 (95.2%) and 118 (94.4%) were positive by the IS6110, hupB, rpoB, oxyR, and IS1081-based PCR assays respectively. A total of 110 (88%) of the cultured isolates were also identified as MTBC by standard biochemical tests. Of this number, 109 (99.1%), 104 (94.5%), 109 (99.1%), 106 (96.4%) and 104 (94.5%) were positive in the IS6110, hupB, rpoB, oxyR, and IS1081-based PCR assays respectively. Concordant PCR results were obtained for 108 of the 125 samples. The 15 isolates that were negative biochemically scored sensitivities ranging from 100% (for the IS6110 assay) to 86.7% (for the hupB and oxyR assay). The combination of the IS6110 assay, which turned out to be the most sensitive, and each of the other assays gave 100% sensitivity. We conclude that the combined targeting of the IS6110 and rpoB genes is likely to yield the most sensitive PCR procedure for the diagnosis of MTBC infection in the five regions of Cameroon.展开更多
Although conventional coal mine designs are conservative regarding pillar strength,local failures such as roof-falls and pillar bursts still affect mine safety and operations.Previous studies have identified that disc...Although conventional coal mine designs are conservative regarding pillar strength,local failures such as roof-falls and pillar bursts still affect mine safety and operations.Previous studies have identified that discontinuous,layered roof materials have some self-supporting capacity.This research is a preliminary step towards understanding these mechanics in coal-measure rocks.Although others have considered broad conceptual models and simplified analogs for mine roof behavior,this study presents a unique numerical model that more completely represents in-situ roof conditions.The discrete element method(DEM)is utilized to conduct a parametric analysis considering a range of in-situ stress ratios,material properties,and joint networks to determine the parameters controlling the stability of single-entries modeled in two-dimensions.Model results are compared to empirical observations of roof-support effectiveness(ARBS)in the context of the coal mine roof rating(CMRR)system.Results such as immediate roof displacement,overall stability,and statistical relationships between model parameters and outcomes are presented herein.Potential practical applications of this line of research include:(1)roof-support optimization for a range of coal-measure rocks,(2)establishment of a relationship between roof stability and pillar stress,and(3)determination of which parameters are most critical to roof stability and therefore require concentrated evaluation.展开更多
In this study, the effects of acetochlor on the growth of 16 rice varieties were investigated. In addition, the sensitivity of different rice variety to acetochlor and the relationship between sensitivity and variety ...In this study, the effects of acetochlor on the growth of 16 rice varieties were investigated. In addition, the sensitivity of different rice variety to acetochlor and the relationship between sensitivity and variety type were also studied. The effects of acetochlor on the germination of rice were determined in Petri dishes. The inhibitory effects of acetochlor on the seedling height, root length, seedling weight, root weight and other indicators of rice varieties were determined by agar method. The result showed the acetochlor had a certain inhibitory effect on the germination of rice. The low-concentration acetochlor would increase the seedling height and root number. However, when the concentration of acetochlor reached a certain value, its inhibitory effects became obvious. The inhibitory effect of acetochlor on rice roots was stronger than that on rice stems. Among the rice varieties, Sidao had the highest acetochlor tolerance, and Tianyou 3301 had the highest sensitivity to acetochlor. The average inhibition rates of seedling height, fresh seeding weight, root length, fresh plant weight and root number of Sidao in agar culture medium with 0.02 mg/L of acetochlor were 1.46%, 6.42%, 51.06%, 60.87% and -6.45%, respectively, while of Tianyou 3301 were 21.62%, 22.62%, 63.16%, 74.76% and 3.89%, respectively. The sensitivity to acetochlor differed significantly among different rice variety. However, this difference had no significant relationship with variety type.展开更多
The isolates of Phytophthora infestans on tomato in the Guangxi Zhuang Autonomous Region, China, were determined for the sensitivities to metalaxyl, cymoxanil and dimethomorph to give the basic information for integra...The isolates of Phytophthora infestans on tomato in the Guangxi Zhuang Autonomous Region, China, were determined for the sensitivities to metalaxyl, cymoxanil and dimethomorph to give the basic information for integrating disease management. Sensitivities were tested by measuring the radial growth on agar medium amended with fungicide, compared with the floating-leaf-disk method. 239 isolates were collected from eight tomato growing areas during 2000-2006. The testing results indicated that the frequencies of sensitive, intermediate, and resistant isolates to metalaxyl were 42.26, 35.98, and 23.53%, respectively. Variations in sensitivities amongst isolates from different areas or different years were very high for metalaxyl. All isolates from Tianlin and Wuxuan were sensitive to metalaxyl, but the metalaxyl-resistant isolates predominated in Tianyang, with the frequency of 51.35%. The EC50 values of certain isolates from Tianyang were higher than 500 μg·mL^-1 and their resistance levels were over 100 000 folds. Cymoxanil has been used for nearly 10 years in Guangxi, and dimethomorph has been used for 5-6 years. However, there was no decrease in sensitivity of P. infestans populations and the sensitivities of the pathogen were nearly normally distributed. Hence, their mean ECs0 value [cymoxanil （0.1647 ±0.0255） μg·mL^-1, dimethomorph （0.0970 ± 0.0052） μg·mL^-1 could be used as the baseline sensitivities for monitoring the field resistance development. The comparison with the floating-leaf-disk method indicates that both the techniques provided equivalent results. These studies suggested that metalaxyl can be continuously applied in Tianlin, Wuxuan, and Nanning due to the resistant isolates that have not been found, while for those areas with resistant isolate, the use of metalaxyl should be reduced or alternated, and cymoxanil or dimethomorph was recommended for controlling late blight disease of tomato.展开更多
We investigated the sensitivities of atom interferometers in the usual fringe-scanning method （FSM） versus the fringe- locking method （FLM）. The theoretical analysis shows that for typical noises in atom interfero...We investigated the sensitivities of atom interferometers in the usual fringe-scanning method （FSM） versus the fringe- locking method （FLM）. The theoretical analysis shows that for typical noises in atom interferometers, the FSM will degrade the sensitivity while the FLM does not. The sensitivity-improvement factor of the FLM over the FSM depends on the type of noises, which is validated by numerical simulations. The detailed quantitative analysis on this fundamental issue is presented, and our analysis is readily extendable to other kinds of noises as well as other fringe shapes in addition to a cosine one.展开更多
Relative sensitivities of 30 species of common woody plants to simulated acid rain with pH values of 2.0, 2.5, 3.0, 3.5, 4.5 and control were studied. The results showed that 6 species of these plants were sensitive t...Relative sensitivities of 30 species of common woody plants to simulated acid rain with pH values of 2.0, 2.5, 3.0, 3.5, 4.5 and control were studied. The results showed that 6 species of these plants were sensitive to simulated acid rain. The moderate included 18 species. The resistant included 6. Relative sensitivities to ambient acid rain and air pollutants and visible injury degree of 30 species of common woody plants in Chongqing City were investigated. Results showed that 6 species with foliage lesion rate at above 10 percent were sensitive, that 6 species with no lesion were resistant and that other 18 species with lesion at 10 percent below were moderate. Other 7 cities (Guiyang, Zunyi, Duyun, Changsha, Zhuzhou, Liuzhou and Guilin City) were also investigated and results were consistent with those of Chongqing City. The experimental and investigated results showed relative sensitivities and visible injury degree of woody plants to simulated acid rain were consistent with those of the woody plants to ambient acid rain and air pollutants. The sensitive plants may be used as bioindicators to acid rain or air pollutants. The resistant species can be introduced to acid rain and air pollution areas to substitute damaged sensitive plants in order to improve environment.展开更多
Creep forces depend greatly on creepages in the contact area forming between wheel and rail.The creepages are completely determined by the state of ...Creep forces depend greatly on creepages in the contact area forming between wheel and rail.The creepages are completely determined by the state of a wheelset moving on a track.In this paper the contact state of a single rigid wheelset moving on a tangent rigid rail,creepages and their sensitivities to some parameters of contact geometry are analyzed by semi analytical method and numerical method,respectively.Some important ideas will be provided for the studies done on the interactions between wheels and rails at high speed.展开更多
This work extends to fourth-order previously published work on developing the adjoint sensitivity and uncertainty analysis of the numerical model of a <u>p</u>oly<u>e</u>thylene-<u>r</...This work extends to fourth-order previously published work on developing the adjoint sensitivity and uncertainty analysis of the numerical model of a <u>p</u>oly<u>e</u>thylene-<u>r</u>eflected <u>p</u>lutonium (acronym: PERP) OECD/NEA reactor physics benchmark. Previous works showed that the third-order sensitivities of the PERP leakage response with respect to these total microscopic cross sections are far larger than the corresponding 1<sup>st</sup>-order and 2<sup>nd</sup>-order ones, thereby having the largest impact on the uncertainties induced in the PERP benchmark’s response. This finding has motivated the development of the original 4<sup>th</sup>-order formulas presented in this work, which are valid not only for the PERP benchmark but can also be used for computing the 4<sup>th</sup>-order sensitivities of response of any nuclear system involving fissionable material and internal or external neutron sources. Subsequent works will use the adjoint-based mathematical expressions obtained in this work to compute exactly and efficiently the numerical values of the largest fourth-order sensitivities of the PERP benchmark’s response to the total microscopic cross sections, and use them for a pioneering fourth-order uncertainty analysis of the PERP benchmark’s response.展开更多
The dynamic transmission characteristics and the sensitivities of the three stage idler gear system of the new NC power turret are studied in the paper. Considering the strongly nonlinear factors such as the periodica...The dynamic transmission characteristics and the sensitivities of the three stage idler gear system of the new NC power turret are studied in the paper. Considering the strongly nonlinear factors such as the periodically time-varying mesh stiffness, the nonlinear tooth backlash, the lump-parameter model of the gear system is developed with one rotational and two translational freedoms of each gear. The eigen-values and eigenvectors are derived and analyzed on the basis of the real modal theory. The sensitivities of natural frequencies to design parameters including supporting and meshing stiffnesses, gear masses, and moments of inertia by the direct differential method are also calculated. The results show the quantitative and qualitative impact of the parameters to the natural characteristics of the gear system. Furthermore, the periodic steady state solutions are obtained by the numerical approach based on the nonlinear model. These results are employed to gain insights into the primary controlling parameters, to forecast the severity of the dynamic response, and to assess the acceptability of the gear design.展开更多
In this paper, structural static design is considered as a kind of inverse algebraic eigenvalue problem. It is the most important task for the inverse problem to compute the sensitivities of eigenvalues and eigenvecto...In this paper, structural static design is considered as a kind of inverse algebraic eigenvalue problem. It is the most important task for the inverse problem to compute the sensitivities of eigenvalues and eigenvectors. Therefore, a complete set of higher order sensitivity expressions has been presented based on the complex variables theory. These expressions have solid mathematical foundation and practical significance.展开更多
In ballistic penetration, a main failure mode for a projectile is adiabatic shear localization which results in macro cracks developing along ASBs which lead to the fracture of projectile. In this paper, the adiabatic...In ballistic penetration, a main failure mode for a projectile is adiabatic shear localization which results in macro cracks developing along ASBs which lead to the fracture of projectile. In this paper, the adiabatic shear sensitivity and ballistic performances of two high strength steels, 30CrMnSi and 35CrWMo, with similar static mechanical properties were investigated. Split Hopkin- son Pressure Bar （SHPB） for compression loading and ballistic experiments above the velocity of 1 000 m/s against thick concrete targets were performed. The SHPB and ballistic experimental results showed that the 30CrMnSi steel exhibits more adiabatic shear sensitivity, compared with the 35CrWMo steel. Even though these two steels have similar static mechanical properties, the 35CrWMo steel projectile exhibits better penetration performance than the 30CrMnSi projectile due to different adiabatic shear sensitivities.展开更多
The strain rate sensitivity to creep of single crystal Cu（110）, metal tantalum, and 128°Y-X LiNbO3 piezoelectric single crystal were measured at room temperature by MTS Nanoindenter XP. Among the three kinds of...The strain rate sensitivity to creep of single crystal Cu（110）, metal tantalum, and 128°Y-X LiNbO3 piezoelectric single crystal were measured at room temperature by MTS Nanoindenter XP. Among the three kinds of materials studied, Cu showed the highest degree of resistance to creep-induced deformation, which is followed by Ta, while the LiNbO3 single crystal deformed more readily than the others. The values of the steady-state strain rate sensitivities determined by the indentation methods are in the range of 0.002-0.006, 0.02-0.06 and 0.02-0.03 for Cu, Ta, and LiNbO3, respectively. The mechanisms for the indentation-induced creeping behavior and the factors that influenced the creeping are discussed.展开更多
α-Fe2O3 nanoparticles doped with various molar fractions of Cr^3＋ were synthesized by a forced hydrolysis route and were characterized by X-ray diffraction（XRD）,scanning electronic microscopy（SEM）,X-ray photoele...α-Fe2O3 nanoparticles doped with various molar fractions of Cr^3＋ were synthesized by a forced hydrolysis route and were characterized by X-ray diffraction（XRD）,scanning electronic microscopy（SEM）,X-ray photoelectron spectroscopy（XPS） and inductive coupled plasma（ICP） techniques.The particles reserve shuttle-like shape in the presence of Cr^3＋.The crystallite sizes of Fe2O3 become smaller with the increased Cr^3＋ concentration in solution.The responses of Cr doped α-Fe2O3 sensors were studied towards reducing gases such as ethanol,methanol,acetone,gasoline and n-hexane.Gas sensors based on these materials have higher sensitivities and rapid response/recovery time to alcohol than to hydrocarbon.展开更多
Chloride ion transport in reclaimed soil solutions filled with fly ash （FA） was investigated by measuring the hydraulic parameters （i,e. water retention curves and hydraulic conductivity） of three substrates, name...Chloride ion transport in reclaimed soil solutions filled with fly ash （FA） was investigated by measuring the hydraulic parameters （i,e. water retention curves and hydraulic conductivity） of three substrates, namely GSL, GFA, and CFA. Similar simulations were carried out under certain weather conditions. The different boundary conditions of chloride transport were also discussed from FA texture, cover soil thickness, groundwater table level, and initial chloride concentration. Furthermore, the sensitivities of chloride ions to these effect factors were analyzed. The results show that the different top soil thickness and initial chloride concentration have no effect on salinity of topsoil solution in the monitoring points, but they can clearly change the chloride concentration of FA layers. The sensibilities from top soil thickness and initial chloride content are exceedingly weak to the salinity balance based on two dimensions of the time and concentration. While the different FA texture and groundwater table not only affect the salinity equilibrium process of the whole reclaimed soil profile, but also change its balance state. Generally, coarse FA particles and high groundwater table can defer the salinity balance process of the reclaimed soil solution, and they also increase the chloride concentration of FA layer solutions, and even topsoil ones.展开更多
文摘This work presents the results of the exact computation of (180)<sup>3</sup> = 5,832,000 third-order mixed sensitivities of the leakage response of a polyethylene-reflected plutonium (PERP) experimental benchmark with respect to the benchmark’s 180 microscopic total cross sections. This computation was made possible by applying the Third-Order Adjoint Sensitivity Analysis Methodology developed by Cacuci. The numerical results obtained in this work revealed that many of the 3<sup>rd</sup>-order sensitivities are significantly larger than their corresponding 1<sup>st</sup>- and 2<sup>nd</sup>-order ones, which is contrary to the widely held belief that higher-order sensitivities are all much smaller and hence less important than the first-order ones, for reactor physics systems. In particular, the largest 3<sup>rd</sup>-order relative sensitivity is the mixed sensitivity <img src="Edit_754b8437-dfdf-487d-af68-c78c637e6d4e.png" width="180" height="24" alt="" />of the PERP leakage response with respect to the lowest energy-group (30) total cross sections of <sup>1</sup>H (“isotope 6”) and <sup>239</sup>Pu (“isotope 1”). These two isotopes are shown in this work to be the two most important parameters affecting the PERP benchmark’s leakage response. By comparison, the largest 1<sup>st</sup>-order sensitivity is that of the PERP leakage response with respect to the lowest energy-group total cross section of isotope <sup>1</sup>H, having the value <img src="Edit_a5cfcc11-6a99-41ee-b844-a5ee84b454b3.png" width="100" height="24" alt="" />, while the largest 2<sup>nd</sup>-order sensitivity is <img src="Edit_05166a2b-97f7-43f1-98ff-b21368c00228.png" width="120" height="22" alt="" />. The 3<sup>rd</sup>-order sensitivity analysis presented in this work is the first ever such analysis in the field of reactor physics. The consequences of the results presented in this work on the uncertainty analysis of the PERP benchmark’s leakage response will be presented in a subsequent work.
文摘This work presents the “Second-Order Comprehensive Adjoint Sensitivity Analysis Methodology (2<sup>nd</sup>-CASAM)” for the efficient and exact computation of 1<sup>st</sup>- and 2<sup>nd</sup>-order response sensitivities to uncertain parameters and domain boundaries of linear systems. The model’s response (<em>i.e.</em>, model result of interest) is a generic nonlinear function of the model’s forward and adjoint state functions, and also depends on the imprecisely known boundaries and model parameters. In the practically important particular case when the response is a scalar-valued functional of the forward and adjoint state functions characterizing a model comprising N parameters, the 2<sup>nd</sup>-CASAM requires a single large-scale computation using the First-Level Adjoint Sensitivity System (1<sup>st</sup>-LASS) for obtaining all of the first-order response sensitivities, and at most N large-scale computations using the Second-Level Adjoint Sensitivity System (2<sup>nd</sup>-LASS) for obtaining exactly all of the second-order response sensitivities. In contradistinction, forward other methods would require (<em>N</em>2/2 + 3 <em>N</em>/2) large-scale computations for obtaining all of the first- and second-order sensitivities. This work also shows that constructing and solving the 2<sup>nd</sup>-LASS requires very little additional effort beyond the construction of the 1<sup>st</sup>-LASS needed for computing the first-order sensitivities. Solving the equations underlying the 1<sup>st</sup>-LASS and 2<sup>nd</sup>-LASS requires the same computational solvers as needed for solving (<em>i.e.</em>, “inverting”) either the forward or the adjoint linear operators underlying the initial model. Therefore, the same computer software and “solvers” used for solving the original system of equations can also be used for solving the 1<sup>st</sup>-LASS and the 2<sup>nd</sup>-LASS. Since neither the 1<sup>st</sup>-LASS nor the 2<sup>nd</sup>-LASS involves any differentials of the operators underlying the original system, the 1<sup>st</sup>-LASS is designated as a “<u>first-level</u>” (as opposed to a “first-order”) adjoint sensitivity system, while the 2<sup>nd</sup>-LASS is designated as a “<u>second-level</u>” (rather than a “second-order”) adjoint sensitivity system. Mixed second-order response sensitivities involving boundary parameters may arise from all source terms of the 2<sup>nd</sup>-LASS that involve the imprecisely known boundary parameters. Notably, the 2<sup>nd</sup>-LASS encompasses an automatic, inherent, and independent “solution verification” mechanism of the correctness and accuracy of the 2nd-level adjoint functions needed for the efficient and exact computation of the second-order sensitivities.
基金Project(2015B37714)supported by the Fundamental Research Funds for the Central Universities of ChinaProject(51605005)supported by the National Natural Science Foundation of China+1 种基金Project(ZK16-03-03)supported by the Open Foundation of Jiangsu Wind Technology Center,ChinaProject([2013]56)supported by the First Group of 2011 Plan of Jiangsu Province,China
文摘The parameter sensitivities affecting the flutter speed of the NREL （National Renewable Energy Laboratory） 5-MW baseline HAWT （horizontal axis wind turbine） blades are analyzed. An aeroelastic model, which comprises an aerodynamic part to calculate the aerodynamic loads and a structural part to determine the structural dynamic responses, is established to describe the classical flutter of the blades. For the aerodynamic part, Theodorsen unsteady aerodynamics model is used. For the structural part, Lagrange’s equation is employed. The flutter speed is determined by introducing “V–g” method to the aeroelastic model, which converts the issue of classical flutter speed determination into an eigenvalue problem. Furthermore, the time domain aeroelastic response of the wind turbine blade section is obtained with employing Runge-Kutta method. The results show that four cases （i.e., reducing the blade torsional stiffness, moving the center of gravity or the elastic axis towards the trailing edge of the section, and placing the turbine in high air density area） will decrease the flutter speed. Therefore, the judicious selection of the four parameters （the torsional stiffness, the chordwise position of the center of gravity, the elastic axis position and air density） can increase the relative inflow speed at the blade section associated with the onset of flutter.
基金supported by the Chinese Academy of Sciences(KJZD-EW-G03-04)the National Natural Science Foundation of China(41721091,41671071)Open Foundation of State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering(No.2017490711)
文摘Due to global warming, glaciers on the Tibetan Plateau(TP) are experiencing widespread shrinkage; however, the mechanisms controlling glacier variations across the TP are still rather unclear, especially on the northeastern TP. In this study, a physically based, distributed surface-energy and mass-balance model was used to simulate glacier mass balance forced by meteorological data. The model was applied to Laohugou No. 12 Glacier, western Qilian Mountains, China, during2010~2012. The simulated albedo and mass balance were validated and calibrated by in situ measurements. The simulated annual glacier-wide mass balances were-385 mm water equivalent(w.e.) in 2010/2011 and-232 mm w.e. in 2011/2012,respectively. The mean equilibrium-line altitude(ELA) was 5,015 m a.s.l., during 2010~2012, which ascended by 215 m compared to that in the 1970 s. The mean accumulation area ratio(AAR) was 39% during the two years. Climatic-sensitivity experiments indicated that the change of glacier mass balance resulting from a 1.5 °C increase in air temperature could be offset by a 30% increase in annual precipitation. The glacier mass balance varied linearly with precipitation, at a rate of130 mm w.e. per 10% change in total precipitation.
文摘A global forecast model is used to examine various sensitivities of numerical predictions of three extreme winter storms that occurred near the eastern continental margin of North America: the Ohio Valley blizzard of January 1978, the New England blizzard of February 1978, and the Mid-Atlantic cyclone of February 1979. While medium-resolution simulations capture much of the intensification, the forecasts of the precise timing and intensity levels suffer from various degrees of error. The coastal cyclones show a 5-10 hPa dependence on the western North Atlantic sea surface temperature, which is varied within a range (± 2.5℃) compatible with interannual fluctuations. The associated vertical velocities and precipitation rates show proportionately stronger dependences on the ocean temperature perturbations. The Ohio Valley blizzard, which intensified along a track 700-800 km from the coast, shows little sensitivity to ocean temperature. The effect of a shift of - 10?latitude in the position of the snow boundary is negligible in each case. The forecasts depend strongly on the model resolution, and the coarse-resolution forecasts are consistently inferior to the medium-resolution forecasts. Studies of the corresponding sensitivities of extreme cyclonic events over eastern Asia are encouraged in order to identify characteristics that are common to numerical forecasts for the two regions.
基金The Knowledge Innovation Program of Chinese Academy of Sciences (KSCX2-YW-N-065)FP6 projects DISSECT (N°SP22-CT-2004-511060)EPIS-ARS (N°SP22-CT-2004-511603)
文摘The etiological agent of severe acute respiratory syndrome(SARS) was identified as a new coronavirus,termed SARS-CoV. Establishment of an efficient and sensitive diagnostic system of SARS-CoV genetic materials is crucial for SARS control. In this study,we quantified SARS-CoV mRNAs in both infected cell culture lysate and in supernatant by using Real-time quantitative revere transcription-PCR based on EvaGreenTM dye and Taqman-MGB probes. For extensive evaluation of sensitivities and specificities,13 pairs of primers and 4 probes were designed based on different genes of SARS-CoV. Glyceraldehydes-3-phosphate dehydrogenase(GAPDH) was selected as the internal control gene. Results showed that S-gene-specific PCR was the most sensitive for detection,but because of its sequence variability in the different viral strains,primers and a probe based on the N gene were suitable substitutions. Meanwhile,we found the mRNA concentrations in cell culture lysates were much higher than in cell supernatant and facilited more sensitive detection of the SARS-CoV.
文摘The accurate diagnosis of tuberculosis caused by members of the Mycobacterium tuberculosis complex (MTBC) has remained a major challenge in clinical laboratories world-wide. Several studies have evaluated the use of highly specific in-house PCR assays targeting the IS6110, hupB, rpoB, oxyR, and IS1081 genes in the detection of MTBC species with reports on variable sensitivities depending on the geographical sourcing of isolates. In the present investigations, we evaluated the sensitivities of these PCR assays on 125 MTBC cultured isolates from five (West, Centre, Littoral, North West and South West) of the ten regions of Cameroon. Of this number, 124 (99.2%), 117 (93.6%), 123 (99.1%), 119 (95.2%) and 118 (94.4%) were positive by the IS6110, hupB, rpoB, oxyR, and IS1081-based PCR assays respectively. A total of 110 (88%) of the cultured isolates were also identified as MTBC by standard biochemical tests. Of this number, 109 (99.1%), 104 (94.5%), 109 (99.1%), 106 (96.4%) and 104 (94.5%) were positive in the IS6110, hupB, rpoB, oxyR, and IS1081-based PCR assays respectively. Concordant PCR results were obtained for 108 of the 125 samples. The 15 isolates that were negative biochemically scored sensitivities ranging from 100% (for the IS6110 assay) to 86.7% (for the hupB and oxyR assay). The combination of the IS6110 assay, which turned out to be the most sensitive, and each of the other assays gave 100% sensitivity. We conclude that the combined targeting of the IS6110 and rpoB genes is likely to yield the most sensitive PCR procedure for the diagnosis of MTBC infection in the five regions of Cameroon.
基金sponsored by the Alpha Foundation for the Improvement of Mine Safety and Health, Inc. (Alpha Foundation)the funding provided for this project by the Alpha Foundationpartially funded by the National Institute of Occupational Health and Science (NIOSH) under Grant Number 200-2016-90154.
文摘Although conventional coal mine designs are conservative regarding pillar strength,local failures such as roof-falls and pillar bursts still affect mine safety and operations.Previous studies have identified that discontinuous,layered roof materials have some self-supporting capacity.This research is a preliminary step towards understanding these mechanics in coal-measure rocks.Although others have considered broad conceptual models and simplified analogs for mine roof behavior,this study presents a unique numerical model that more completely represents in-situ roof conditions.The discrete element method(DEM)is utilized to conduct a parametric analysis considering a range of in-situ stress ratios,material properties,and joint networks to determine the parameters controlling the stability of single-entries modeled in two-dimensions.Model results are compared to empirical observations of roof-support effectiveness(ARBS)in the context of the coal mine roof rating(CMRR)system.Results such as immediate roof displacement,overall stability,and statistical relationships between model parameters and outcomes are presented herein.Potential practical applications of this line of research include:(1)roof-support optimization for a range of coal-measure rocks,(2)establishment of a relationship between roof stability and pillar stress,and(3)determination of which parameters are most critical to roof stability and therefore require concentrated evaluation.
基金Supported by Graduate Research and Innovation Projects in Hunan Province(CX2013B418)Industrialization Cultivation Projects in Colleges and Universities of Hunan Province(13CY030)~~
文摘In this study, the effects of acetochlor on the growth of 16 rice varieties were investigated. In addition, the sensitivity of different rice variety to acetochlor and the relationship between sensitivity and variety type were also studied. The effects of acetochlor on the germination of rice were determined in Petri dishes. The inhibitory effects of acetochlor on the seedling height, root length, seedling weight, root weight and other indicators of rice varieties were determined by agar method. The result showed the acetochlor had a certain inhibitory effect on the germination of rice. The low-concentration acetochlor would increase the seedling height and root number. However, when the concentration of acetochlor reached a certain value, its inhibitory effects became obvious. The inhibitory effect of acetochlor on rice roots was stronger than that on rice stems. Among the rice varieties, Sidao had the highest acetochlor tolerance, and Tianyou 3301 had the highest sensitivity to acetochlor. The average inhibition rates of seedling height, fresh seeding weight, root length, fresh plant weight and root number of Sidao in agar culture medium with 0.02 mg/L of acetochlor were 1.46%, 6.42%, 51.06%, 60.87% and -6.45%, respectively, while of Tianyou 3301 were 21.62%, 22.62%, 63.16%, 74.76% and 3.89%, respectively. The sensitivity to acetochlor differed significantly among different rice variety. However, this difference had no significant relationship with variety type.
文摘The isolates of Phytophthora infestans on tomato in the Guangxi Zhuang Autonomous Region, China, were determined for the sensitivities to metalaxyl, cymoxanil and dimethomorph to give the basic information for integrating disease management. Sensitivities were tested by measuring the radial growth on agar medium amended with fungicide, compared with the floating-leaf-disk method. 239 isolates were collected from eight tomato growing areas during 2000-2006. The testing results indicated that the frequencies of sensitive, intermediate, and resistant isolates to metalaxyl were 42.26, 35.98, and 23.53%, respectively. Variations in sensitivities amongst isolates from different areas or different years were very high for metalaxyl. All isolates from Tianlin and Wuxuan were sensitive to metalaxyl, but the metalaxyl-resistant isolates predominated in Tianyang, with the frequency of 51.35%. The EC50 values of certain isolates from Tianyang were higher than 500 μg·mL^-1 and their resistance levels were over 100 000 folds. Cymoxanil has been used for nearly 10 years in Guangxi, and dimethomorph has been used for 5-6 years. However, there was no decrease in sensitivity of P. infestans populations and the sensitivities of the pathogen were nearly normally distributed. Hence, their mean ECs0 value [cymoxanil （0.1647 ±0.0255） μg·mL^-1, dimethomorph （0.0970 ± 0.0052） μg·mL^-1 could be used as the baseline sensitivities for monitoring the field resistance development. The comparison with the floating-leaf-disk method indicates that both the techniques provided equivalent results. These studies suggested that metalaxyl can be continuously applied in Tianlin, Wuxuan, and Nanning due to the resistant isolates that have not been found, while for those areas with resistant isolate, the use of metalaxyl should be reduced or alternated, and cymoxanil or dimethomorph was recommended for controlling late blight disease of tomato.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.41127002,11574099,41504034,and 11474115)the National Basic Research Program of China(Grant No.2010CB832806)
文摘We investigated the sensitivities of atom interferometers in the usual fringe-scanning method （FSM） versus the fringe- locking method （FLM）. The theoretical analysis shows that for typical noises in atom interferometers, the FSM will degrade the sensitivity while the FLM does not. The sensitivity-improvement factor of the FLM over the FSM depends on the type of noises, which is validated by numerical simulations. The detailed quantitative analysis on this fundamental issue is presented, and our analysis is readily extendable to other kinds of noises as well as other fringe shapes in addition to a cosine one.
文摘Relative sensitivities of 30 species of common woody plants to simulated acid rain with pH values of 2.0, 2.5, 3.0, 3.5, 4.5 and control were studied. The results showed that 6 species of these plants were sensitive to simulated acid rain. The moderate included 18 species. The resistant included 6. Relative sensitivities to ambient acid rain and air pollutants and visible injury degree of 30 species of common woody plants in Chongqing City were investigated. Results showed that 6 species with foliage lesion rate at above 10 percent were sensitive, that 6 species with no lesion were resistant and that other 18 species with lesion at 10 percent below were moderate. Other 7 cities (Guiyang, Zunyi, Duyun, Changsha, Zhuzhou, Liuzhou and Guilin City) were also investigated and results were consistent with those of Chongqing City. The experimental and investigated results showed relative sensitivities and visible injury degree of woody plants to simulated acid rain were consistent with those of the woody plants to ambient acid rain and air pollutants. The sensitive plants may be used as bioindicators to acid rain or air pollutants. The resistant species can be introduced to acid rain and air pollution areas to substitute damaged sensitive plants in order to improve environment.
文摘Creep forces depend greatly on creepages in the contact area forming between wheel and rail.The creepages are completely determined by the state of a wheelset moving on a track.In this paper the contact state of a single rigid wheelset moving on a tangent rigid rail,creepages and their sensitivities to some parameters of contact geometry are analyzed by semi analytical method and numerical method,respectively.Some important ideas will be provided for the studies done on the interactions between wheels and rails at high speed.
文摘This work extends to fourth-order previously published work on developing the adjoint sensitivity and uncertainty analysis of the numerical model of a <u>p</u>oly<u>e</u>thylene-<u>r</u>eflected <u>p</u>lutonium (acronym: PERP) OECD/NEA reactor physics benchmark. Previous works showed that the third-order sensitivities of the PERP leakage response with respect to these total microscopic cross sections are far larger than the corresponding 1<sup>st</sup>-order and 2<sup>nd</sup>-order ones, thereby having the largest impact on the uncertainties induced in the PERP benchmark’s response. This finding has motivated the development of the original 4<sup>th</sup>-order formulas presented in this work, which are valid not only for the PERP benchmark but can also be used for computing the 4<sup>th</sup>-order sensitivities of response of any nuclear system involving fissionable material and internal or external neutron sources. Subsequent works will use the adjoint-based mathematical expressions obtained in this work to compute exactly and efficiently the numerical values of the largest fourth-order sensitivities of the PERP benchmark’s response to the total microscopic cross sections, and use them for a pioneering fourth-order uncertainty analysis of the PERP benchmark’s response.
基金The China Major Scientific and Technological Programs(2009ZX04011-053)the China NSFC Fund(50975047)
文摘The dynamic transmission characteristics and the sensitivities of the three stage idler gear system of the new NC power turret are studied in the paper. Considering the strongly nonlinear factors such as the periodically time-varying mesh stiffness, the nonlinear tooth backlash, the lump-parameter model of the gear system is developed with one rotational and two translational freedoms of each gear. The eigen-values and eigenvectors are derived and analyzed on the basis of the real modal theory. The sensitivities of natural frequencies to design parameters including supporting and meshing stiffnesses, gear masses, and moments of inertia by the direct differential method are also calculated. The results show the quantitative and qualitative impact of the parameters to the natural characteristics of the gear system. Furthermore, the periodic steady state solutions are obtained by the numerical approach based on the nonlinear model. These results are employed to gain insights into the primary controlling parameters, to forecast the severity of the dynamic response, and to assess the acceptability of the gear design.
文摘In this paper, structural static design is considered as a kind of inverse algebraic eigenvalue problem. It is the most important task for the inverse problem to compute the sensitivities of eigenvalues and eigenvectors. Therefore, a complete set of higher order sensitivity expressions has been presented based on the complex variables theory. These expressions have solid mathematical foundation and practical significance.
文摘In ballistic penetration, a main failure mode for a projectile is adiabatic shear localization which results in macro cracks developing along ASBs which lead to the fracture of projectile. In this paper, the adiabatic shear sensitivity and ballistic performances of two high strength steels, 30CrMnSi and 35CrWMo, with similar static mechanical properties were investigated. Split Hopkin- son Pressure Bar （SHPB） for compression loading and ballistic experiments above the velocity of 1 000 m/s against thick concrete targets were performed. The SHPB and ballistic experimental results showed that the 30CrMnSi steel exhibits more adiabatic shear sensitivity, compared with the 35CrWMo steel. Even though these two steels have similar static mechanical properties, the 35CrWMo steel projectile exhibits better penetration performance than the 30CrMnSi projectile due to different adiabatic shear sensitivities.
基金This work was financially supported by the National Natural Science Foundation of China (No.90406024).
文摘The strain rate sensitivity to creep of single crystal Cu（110）, metal tantalum, and 128°Y-X LiNbO3 piezoelectric single crystal were measured at room temperature by MTS Nanoindenter XP. Among the three kinds of materials studied, Cu showed the highest degree of resistance to creep-induced deformation, which is followed by Ta, while the LiNbO3 single crystal deformed more readily than the others. The values of the steady-state strain rate sensitivities determined by the indentation methods are in the range of 0.002-0.006, 0.02-0.06 and 0.02-0.03 for Cu, Ta, and LiNbO3, respectively. The mechanisms for the indentation-induced creeping behavior and the factors that influenced the creeping are discussed.
基金Supported by the National Natural Science Foundation of China(No.40772026)
文摘α-Fe2O3 nanoparticles doped with various molar fractions of Cr^3＋ were synthesized by a forced hydrolysis route and were characterized by X-ray diffraction（XRD）,scanning electronic microscopy（SEM）,X-ray photoelectron spectroscopy（XPS） and inductive coupled plasma（ICP） techniques.The particles reserve shuttle-like shape in the presence of Cr^3＋.The crystallite sizes of Fe2O3 become smaller with the increased Cr^3＋ concentration in solution.The responses of Cr doped α-Fe2O3 sensors were studied towards reducing gases such as ethanol,methanol,acetone,gasoline and n-hexane.Gas sensors based on these materials have higher sensitivities and rapid response/recovery time to alcohol than to hydrocarbon.
基金Supported by the National Natural Science Foundation of China （51274013） the International Cooperation Projects of Anhui, China （10080703026） Acknowledgements We thank the work group of soil information systems and solute transport models from Osnabrueck University of Applied Sciences, Germany for providing us their experimental work.
文摘Chloride ion transport in reclaimed soil solutions filled with fly ash （FA） was investigated by measuring the hydraulic parameters （i,e. water retention curves and hydraulic conductivity） of three substrates, namely GSL, GFA, and CFA. Similar simulations were carried out under certain weather conditions. The different boundary conditions of chloride transport were also discussed from FA texture, cover soil thickness, groundwater table level, and initial chloride concentration. Furthermore, the sensitivities of chloride ions to these effect factors were analyzed. The results show that the different top soil thickness and initial chloride concentration have no effect on salinity of topsoil solution in the monitoring points, but they can clearly change the chloride concentration of FA layers. The sensibilities from top soil thickness and initial chloride content are exceedingly weak to the salinity balance based on two dimensions of the time and concentration. While the different FA texture and groundwater table not only affect the salinity equilibrium process of the whole reclaimed soil profile, but also change its balance state. Generally, coarse FA particles and high groundwater table can defer the salinity balance process of the reclaimed soil solution, and they also increase the chloride concentration of FA layer solutions, and even topsoil ones.
