Linearized waveform inversion for vertical transversely isotropic elastic media:Methodology and multi-parameter crosstalk analysis

Seismic migration and inversion are closely related techniques to portray subsurface images and identify hydrocarbon reservoirs.Seismic migration aims at obtaining structural images of subsurface geologic discontinuities.More specifically,seismic migration estimates the reflectivity function(stacked average reflectivity or pre-stack angle-dependent reflectivity)from seismic reflection data.On the other hand,seismic inversion quantitatively estimates the intrinsic rock properties of subsurface formulations.Such seismic inversion methods are applicable to detect hydrocarbon reservoirs that may exhibit lateral variations in the inverted parameters.Although there exist many differences,pre-stack seismic migration is similar with the first iteration of the general linearized seismic inversion.Usually,seismic migration and inversion techniques assume an acoustic or isotropic elastic medium.Unconventional reservoirs such as shale and tight sand formation have notable anisotropic property.We present a linearized waveform inversion(LWI)scheme for weakly anisotropic elastic media with vertical transversely isotropic(VTI)symmetry.It is based on two-way anisotropic elastic wave equation and simultaneously inverts for the localized perturbations(ΔVp_(0)/Vp_(0)/Vs_(0)/Vs_(0)/,Δ∈,Δδ)from the long-wavelength reference model.Our proposed VTI-elastic LWI is an iterative method that requires a forward and an adjoint operator acting on vectors in each iteration.We derive the forward Born approximation operator by perturbation theory and adjoint operator via adjoint-state method.The inversion has improved the quality of the images and reduces the multi-parameter crosstalk comparing with the adjoint-based images.We have observed that the multi-parameter crosstalk problem is more prominent in the inversion images for Thomsen anisotropy parameters.Especially,the Thomsen parameter is the most difficult to resolve.We also analyze the multi-parameter crosstalk using scattering radiation patterns.The linearized waveform inversion for VTI-elastic media presented in this article provides quantitative information of the rock properties that has the potential to help identify hydrocarbon reservoirs.

Preliminary Study on the Occurrence of Maize Diseases in Anhui Province

The occurrence of maize diseases was systematically studied at different growth stages of maize in different areas of Anhui Province. It was found that maize has a long optimal growth period in Anhui Province, and the maize planting structure is complex. The northern region is mainly planted with summer maize in large scale, while the southern region is mainly planted with spring maize in scattered pattern. In terms of diseases, the south spring maize suffered from more diverse diseases than the north summer maize. The main maize disease in Suzhou, Bozhou, Fuyang and Bengbu areas was southern rust, which was common with the highest diseased plant rate of 76%. The main maize diseases in Lu'an, Anqing, Chizhou, Tongling and Xuancheng were rust, maize rough dwarf virus(MRDV), southern leaf blight and sheath blight. Other diseases such as northern leaf blight, stalk rot and maize smut occurred commonly. The diseased plant rate of maize rust was in the range of 25%-47%.

聚多巴胺固定的聚(2-甲基-2-噁唑啉)/聚(4-乙烯吡啶)混合刷对胃蛋白酶的可控吸附

在聚多巴胺修饰的基底表面同时接枝端基为氨基的聚(2-甲基-2-噁唑啉)和端基为巯基的聚(4-乙烯吡啶),制备了聚(2-甲基-2-噁唑啉)/聚(4-乙烯吡啶)混合刷.通过X射线光电子能谱、可变角光谱型椭偏仪、zeta电位仪和静态水接触角对涂层进行表征.结果表明,混合刷的组成可以通过改变聚(2-甲基-2-噁唑啉)和聚(4-乙烯吡啶)的投料比控制.此外,改变环境pH值和混合刷组成比例可以调节混合刷涂层表面的zeta电位和水接触角.采用异硫氰酸荧光素标记胃蛋白酶.和表面等离子体共振研究了胃蛋白酶在聚(2-甲基-2-噁唑啉)/聚(4-乙烯吡啶)混合刷表面的响应性吸附/脱附能力结果表明,通过调整聚(2-甲基-2-噁唑啉)或聚(4-乙烯吡啶)的组分比,在pH=3时,聚(2-甲基-2-噁唑啉)/聚(4-乙烯吡啶)混合刷表面可以吸附大量的胃蛋白酶;在pH=7时,脱附效率达到92%以上.

邻近建筑城市隧道爆破振动影响规律研究

为探明火凤山隧道加宽段爆破开挖对邻近建筑和先行洞的影响,本文通过有限差分软件FLAC3D对火凤山隧道左线20m加宽段进行爆破模拟计算,研究了爆破振动在工程区的传播规律、爆破对小净距隧道影响以及爆破对地表建筑的影响。

Different Turbulent Regimes and Vertical Turbulence Structures of the Urban Nocturnal Stable Boundary Layer

Turbulence in the nocturnal boundary layer(NBL)is still not well characterized,especially over complex underlying surfaces.Herein,gradient tower data and eddy covariance data collected by the Beijing 325-m tower were used to better understand the differentiating characteristics of turbulence regimes and vertical turbulence structure of urban the NBL.As for heights above the urban canopy layer(UCL),the relationship between turbulence velocity scale(VTKE)and wind speed(V)was consistent with the“HOckey-Stick”(HOST)theory proposed for a relatively flat area.Four regimes have been identified according to urban nocturnal stable boundary layer.Regime 1 occurs where local shear plays a leading role for weak turbulence under the constraint that the wind speed V<VT(threshold wind speed).Regime 2 is determined by the existence of strong turbulence that occurs when V>VT and is mainly driven by bulk shear.Regime 3 is identified by the existence of moderate turbulence when upside-down turbulence sporadic bursts occur in the presence of otherwise weak turbulence.Regime 4 is identified as buoyancy turbulence,when V>VT,and the turbulence regime is affected by a combination of local wind shear,bulk shear and buoyancy turbulence.The turbulence activities demonstrated a weak thermal stratification dependency in regime 1,for which within the UCL,the turbulence intensity was strongly affected by local wind shear when V<VT.This study further showed typical examples of different stable boundary layers and the variations between turbulence regimes by analyzing the evolution of wind vectors.Partly because of the influence of large-scale motions,the power spectral density of vertical velocity for upsidedown structure showed an increase at low frequencies.The upside-down structures were also characterized by the highest frequency of the stable stratifications in the higher layer.

Simulation and optimization of scrap wagon dismantling system based on Plant Simulation

Based on the existing plant layout and process flow,a simulation analysis was conducted using the Plant Simulation platform with the utilization efficiency of each station and production capacity of the dismantling system as indicators.A problem with long-term suspension in the disassembly process was determined.Based on the two optimization directions of increasing material transportation equipment and expanding the buffer capacity,a cost-oriented optimization model is established.A genetic algorithm and model simulation were used to solve the model.An optimization scheme that satisfies the production needs and has the lowest cost is proposed.The results show that the optimized dismantling system solves the suspended work problem at the dismantling station and a significant improvement in productivity and station utilization efficiency compared with the previous system.

Recent advancements in metal-organic frameworks for green applications

A series of environmental and energy issues,such as global warming,water pollution,acid rain,and energy shortage,have to be settled urgently.Metal-organic frameworks(MOFs)are compounds consisting of metal ions or clusters coordinated to organic ligands,which show great promise for alleviating or mitigating these challenges owing to their outstanding physical and chemical properties.In this review,we summarize the recent advances of MOFs in the fields of green applications,including carbon capture,harmful gas removal,sewage treatment,and green energy storage.In addition,the challenges and prospects of the large-scale commercialized use of MOFs in handling environmental issues are also discussed.

Long-term Correlations and Extreme Wind Speed Estimations

In this paper, we use fluctuation analysis to study statistical correlations in wind speed time series. Each time series used here was recorded hourly over 40 years. The fluctuation functions of wind speed time series were found to scale with a universal exponent approximating to 0.7, which means that the wind speed time series are long-term correlated. In the classical method of extreme estimations, data are commonly assumed to be independent (without correlations). This assumption will lead to an overestimation if data are long-term correlated. We thus propose a simple method to improve extreme wind speed estimations based on correlation analysis. In our method, extreme wind speeds are obtained by simply scaling the mean return period in the classical method. The scaling ratio is an analytic function of the scaling exponent in the fluctuation analysis.

High-Order Statistics of Temperature Fluctuations in an Unstable Atmospheric Surface Layer over Grassland

Skewness(S) and kurtosis(K) of temperature in the surface layer over a grassland are investigated under unstable thermal stratifications. We find that both skewness and kurtosis generally obey Monin–Obukhov similarity theory and tend to be constant values(1.5 and 5.3, respectively) when the stability parameter z/L <-2. Quantitative formulas of the similarity functions are proposed. The temperature probability density function(PDF) is close to Gaussian in near neutral stratification and non-Gaussian in unstable stratification. The influence of coherent motions on the PDF behavior is analyzed using the quadrant analysis technique. It shows that PDF behaviors are controlled by ejections and sweeps. The results also indicate that the PDF type of the ejections always follows a Gaussian distribution, while the PDF of the sweeps changes with stability.

Experimental study of the dust-removal performance of a wet scrubber

A variety of dust control methods are often applied in coal mines,among which the application of wet scrubbers has proven to be an efficient technology for the removal of dust in airstreams,rather than diluting or confining the dust.In this paper,a wet scrubber design was developed.Based on a self-designed experimental test platform,the total dust concentration,respirable dust concentration,air volume,and average pressure drops of wet scrubbers with 12,16,20,and 24 blades were measured under different water intake conditions.The results show that the different water intake levels have only minimal effects on the air volume of the wet scrubbers.However,increased water intake had improved the dust removal efficiency of the wet scrubbers with the same number of blades.The wet scrubber with 16 blades was found to have the best dust removal efficiency at a water intake level of 1.35 m^(3)/h.Its total dust and respirable dust removal efficiency reached 96.81%and 95.59%,respectively.The air volume was 200.4 m^(3)/min,and the average pressure drop was determined to be 169.4 Pa.In addition,when the wet scrubber with 16 blades was applied in a coal preparation plant in China's Shanxi Province,it was observed that the total dust concentration had fallen below 8.1 mg/m^(3),and the respirable dust concentration had fallen below 5.9 mg/m^(3).Therefore,the results obtained in this research investigation provide important references for the use of wet scrubbers to improve coal production environmental conditions.

A new fast algorithm for multitarget tracking in dense clutter

A fast joint probabilistic data association （FJPDA） algorithm is proposed in tiffs paper. Cluster probability matrix is approximately calculated by a new method, whose elements βi^t（K） can be taken as evaluation functions. According to values of βi^t（K）, N events with larger joint probabilities can be searched out as the events with guiding joint probabilities, tiros, the number of searching nodes will be greatly reduced. As a result, this method effectively reduces the calculation load and nnkes it possible to be realized on real-thne, Theoretical ,analysis and Monte Carlo simulation results show that this method is efficient.

Application of FLUENT on fine-scale simulation of wind field over complex terrain

The state-of-art Computational Fluid Dynamics （CFD） codes FLUENT is applied in a fine-scale simulation of the wind field over a complex terrain. Several numerical tests are performed to validate the capability of FLUENT on describing the wind field details over a complex terrain. The results of the numerical tests show that FLUENT can simulate the wind field over extremely complex terrain, which cannot be simulated by mesoscale models. The reason why FLUENT can cope with extremely complex terrain, which can not be coped with by mesoscale models, relies on some particular techniques adopted by FLUENT, such as computer-aided design （CAD） technique, unstructured grid technique and finite volume method. Compared with mesoscale models, FLUENT can describe terrain in much more accurate details and can provide wind simulation results with higher resolution and more accuracy.

Clinical characteristics and outcomes of primary intracranial alveolar soft-part sarcoma: A case report

BACKGROUND Primary intracranial alveolar soft-part sarcoma(PIASPS)is a rare malignancy.We aimed to investigate the clinical profiles and outcomes for PIASPS.CASE SUMMARY We firstly reported five consecutive cases from our institute.Then,the cases from previous studies were pooled and analyzed to delineate the characteristics of this disease.Our cohort included two males and three females.The median age was 21-years-old(range:8-54-years-old).All the patients received surgical treatment.Gross total resection(GTR),radiotherapy,and chemotherapy were administered in 3 patients,4 patients,and 1 patient,respectively.After a median follow-up of 36 mo,tumor progression was noticed in 4 patients;and 3 patients died of the disease.Pooled data(n=14)contained 5 males and 9 females with a median age of 19 years.The log-rank tests showed that GTR(P=0.011)could prolong progression-free survival,and radiotherapy(P<0.001)resulted in longer overall survival.CONCLUSION Patients with PIASPS suffer from poor outcomes.Surgical treatment is the first choice,and GTR should be achieved when the tumor is feasible.Patients with PIASPS benefit from radiotherapy,which should be considered as a part of treatment therapies.

Positive and negative turbulent heat diffusivity observed on a 325-m meteorological tower in Beijing

Turbulent diffusion efficiently transports momentum,heat,and matter and affects their transfers between the atmosphere and the surface.As a key parameter in describing turbulent diffusion,the turbulent heat diffusivity KH has rarely been studied in the context of frequent urban pollution in recent years.In this study,KH under urban pollution conditions was directly calculated based on K-theory.The authors found an obvious diurnal variation in K_(H),with variations also in the vertical distributions between each case and over time.Interestingly,the height corresponding to the high occurrence frequency of negative K_(H) rises gradually after sunrise,peaks at noon,falls near sunset,and concentrates around 140 m during most of the night.The KH magnitude and fluctuation are smaller in the pollutant accumulation stage(CS)at all levels than in the pollutant transport stage and pollutant removal stage.Turbulent diffusion may greatly affect PM_(2.5) concentrations at the CS because of the negative correlation between PM_(2.5) concentrations and the absolute value of KH at the CS accompanied by weak wind speeds.The applicability of K-theory is not very good during either day or at night.These problems are inherent in K-theory when characterizing complex systems,such as turbulent diffusion,and require new frameworks or parameterization schemes.These findings may provide valuable insight for establishing a new turbulence diffusion parameterization scheme for KH and promote the study of turbulent diffusion,air quality forecasting,and weather and climate modeling.

Improving the performance of crystalline Si solar cell by high-pressure hydrogenation

We report an approach of high-pressure hydrogenation to improve the performance of crystalline Si(c-Si) solar cells.As-received p-type c-Si wafer-based PN junctions were subjected to high-pressure(2.5 MPa) hydrogen atmosphere at 200 ℃,followed by evaporating antireflection layers,passivation layers,and front and rear electrodes.The efficiency of the so prepared c-Si solar cell was found to increase evidently after high-pressure hydrogenation,with a maximal enhancement of 10%.The incorporation of hydrogen by Si solar cells was identified,and hydrogen passivation of dangling bonds in Si was confirmed.Compared to the regular approach of hydrogen plasma passivation,the approach of high-pressure hydrogenation reported here needs no post-hydrogenation treatment,and can be more convenient and efficient to use in improving the performances of the c-Si and other solar cells.

Study on the Relationship of Spray Rate to Air Pressure and Gravity Drop of Siphonic Nozzle

In order to further clarify the spraying performance of siphonic nozzle, the spray rate of siponic cone nozzle with aperture of 1.0 mm was determined at 15 different air pressure levels and 12 gravity drop levels, and DPS and SPSS were used to make the difference analysis and modeling, which clarified the relationship between the spray rate of the siphonic cone nozzle with aperture of 1.0 mm and air pressure and gravity drop, getting the regression equation of Y=406.854P＋ 1.904G＋77.524. The study could provide a theoretical basis for the optimization and improvement of plant protection spraying equipment.

Texture ZnO Thin-Films and their Application as Front Electrode in Solar Cells

In this paper, three kinds of textured ZnO thin-films (the first kind has the textured structure with both columnar and polygon, the second posses pyramid-like textured structure only, and the third has the textured structure with both crater-like and pyramid-like), were prepared by three kinds of methods, and the application of these ZnO thin-films as a front electrode in solar cell was studied, respectively. In the first method with negative bias voltage and appropriate sputtering parameters, the textured structure with columnar and polygon on the surface of ZnO thin-film are both existence for the sample prepared by direct magnetron sputtering. Using as a front electrode in solar cell, the photoelectric conversion efficiency Eff of 7.00% was obtained. The second method is that by sputtering on the ZnO:Al self-supporting substrate, and the distribution of pyramid-like was gained. Moreover, the higher (8.25%) photoelectric conversion efficiency of solar cell was got. The last method is that by acid-etching the as-deposited ZnO thin-film which possesses mainly both columnar and polygon structure, and the textured ZnO thin-film with both crater-like and pyramid-like structure was obtained, and the photoelectric conversion efficiency of solar cell is 7.10% when using it as front electrode. These results show that the textured ZnO thin-film prepared on self-supporting substrate is more suitable for using as a front electrode in amorphous silicon cells.

A Consortium Blockchain-enabled Double Auction Mechanism for Peer-to-peer Energy Trading among Prosumers

This paper investigates a double auction-based peer-to-peer(P2P)energy trading market for a community of renewable prosumers with private information on reservation price and quantity of energy to be traded.A novel competition padding auction(CPA)mechanism for P2P energy trading is proposed to address the budget deficit problem while holding the advantages of the widely-used Vickrey-Clarke-Groves mechanism.To illustrate the theoretical properties of the CPA mechanism,the sufficient conditions are identified for a truth-telling equilibrium with a budget surplus to exist,while further proving its asymptotical economic efficiency.In addition,the CPA mechanism is implemented through consortium blockchain smart contracts to create safer,faster,and larger P2P energy trading markets.The proposed mechanism is embedded into blockchain consensus protocols for high consensus efficiency,and the budget surplus of the CPA mechanism motivates the prosumers to manage the blockchain.Case studies are carried out to show the effectiveness of the proposed method.

Deep Weighted Fusion Learning(DWFL)-based multi-sensor fusion model for accurate building occupancy detection

With the advancement of artificial intelligence,the dominance of deep learning(DL)models over ordinary machine learning(ML)algorithms has become a reality in recent years due to its capability of handling complex pattern recognition without manual feature pre-definition.With the growing demands for power savings,building energy loss reduction could benefit from DL techniques.For buildings/rooms with the varying number of occupants,heating,ventilation,and air conditioning(HVAC)systems are often found in operations without much necessity.To reduce the building’s energy loss,accurate occupancy detection/prediction(ODP)results could be used to control the proper operations of HVACs.However,ODP is a challenging issue due to multiple reasons,such as improper selection/deployment of sensors,inefficient learning algorithms for pattern recognition,varying room conditions,etc.To overcome the above challenges,we propose a DL-based framework,i.e.,Deep Weighted Fusion Learning(DWFL),to detect and predict occupancy counts with optimal multi-sensor fusion structure.DWFL fuses the extracted features from multiple types of sensors with the priority/weight assignment to each sensor.Such weight assignment considers different room conditions and the pros/cons of each type of sensor.To evaluate DWFL model in terms of occupancy prediction accuracy,we have set up an experimental testbed with low-cost cameras,carbon dioxide(CO_(2)),and passive infrared(PIR)sensors.Among the recently proposed occupancy detection models,DeepFusion utilized deep learning model on heterogeneous sensor data and achieved 88%accuracy in occupancy count estimation(Xue et al.,2019).Another deep learning-based model MI-PIR achieved 91%accuracy on raw analog data from PIR sensors(Andrews et al.,2020).Our research outcome is 94%.Therefore,the experiment results show that our DWFL scheme outperforms the state-of-the-art ODP methods by 3%.

Observed and simulated features of the CO_2 diurnal cycle in the boundary layer at Beijing and Hefei,China

The mechanism of the CO2diurnal cycle is a basis for investigating the carbon budget and its impacts on climate and environment change.Regional diurnal variations in CO2concentration based on observations and modeling have been studied widely.However,few studies have focused on the pattern of the CO2diurnal cycle in China.In this study,a three-dimensional global chemical transport model,Goddard Earth Observing System(GEOS)-Chem,was applied to simulate the CO2concentration and its variation over China from 2004 to 2012.Meanwhile,we also analyzed the CO2concentration as observed by two eddy covariance flux observation towers,one located in Beijing(39°580N,116°220E)and one in Hefei(31°550N,117°100E),using LI-COR 7500A infrared gas analyzers.Observations showed the amplitude of the CO2diurnal cycle at Hefei to be larger than at Beijing,due to stronger ecological activities.GEOS-Chem successfully captured the main aspects of the diurnal cycle of the CO2concentration in the boundary layer observed at both Beijing and Hefei.However,some discrepancies between the model and observations did exist;specifically,the model tended to underestimate the amplitude of the CO2diurnal cycle.The data also showed that traffic emissions significantly enhanced the CO2concentration in the boundary layer.