Population parameters and dynamic pool models of commercial fishes in the Beibu Gulf, northern South China Sea

Length-frequency data of eight commercial fish species in the Beibu Gulf （Golf of Tonkin）, northern South China Sea, were collected during 2006-2007. Length-weight relationships and growth and mortality parameters were analyzed using FiSAT II software. Five species had isometric growth, two species had negative allometric growth, and one species had positive allometric growth. Overall, the exploitation rates of the eight species were lower in 2006 2007 than in 1997-1999： for four species （Saurida tumbil, Saurida undosquamis, Argyrosomus macrocephalus, and Nemipterus virgatus） it was lower in 2006-2007 than in 1997 1999, for two species （Parargyrops edita and Trichiurus haumela） it remained the same, and for the other two species （Trachurus japonicus and Decapterus maruadsi） it was higher in 2006~007 than in 1997-1999. The exploitation rates might have declined because of the decline in fishing intensity caused by high crude oil prices. The optimum exploitation rate, estimated using Beverton-Holt dynamic pool models, indicated that although fishes in the Beibu Gulf could sustain high exploitation rates, the under-size fishes at first capture resulted in low yields. To increase the yield per recruitment, it is more effective to increase the size at first capture than to control fishing effort.

An Improved Three-Dimensional Non-Equilibrium Mixing Pool Model

This paper presents an improved three-dimensional non-equilibrium mixing pool model.It is a simplified form of the original model and is more practical for applications.The simulation re-sults show that the industrial scale distillation tray columns can be described closely by the improvedmodel.The effects of model parameters,such as the number of mixing pools,the point efficiencyand flow pattern,on separation are analyzed quantitatively.

Western Pacific Warm Pool and ENSO Asymmetry in CMIP3 Models

Theoretical and empirical studies have suggested that an underestimate of the ENSO asymmetry may be accompanied by a climatologically smaller and warmer western Pacific warm pool. In light of this suggestion, simulations of the tropical Pacific climate by 19 Coupled Model Intercomparison Project Phase 3 （CMIP3） climate models that do not use flux adjustment were evaluated. Our evaluation revealed systematic biases in both the mean state and ENSO statistics. The mean state in most of the models had a smaller and warmer warm pool. This common bias in the mean state was accompanied by a common bias in the simulated ENSO statistics： a significantly weak asymmetry between the two phases of ENSO. Moreover, despite the generally weak ENSO asymmetry simulated by all models, a positive correlation between the magnitude of the bias in the simulated warm-pool size and the magnitude of the bias in the simulated ENSO asymmetry was found. These findings support the suggested link between ENSO asymmetry and the tropical mean state--the climatological size and temperature of the warm pool in particular. Together with previous studies, these findings light up a path to improve the simulation of the tropical Pacific mean state by climate models： enhancing the asymmetry of ENSO in the climate models.

Equality Testing for Soil Grid Unit Resolutions to Polygon Unit Scales with DNDC Modeling of Regional SOC Pools

Matching soil grid unit resolutions with polygon unit map scales is important to minimize the uncertainty of regional soil organic carbon(SOC) pool simulation due to their strong influences on the modeling.A series of soil grid units at varying cell sizes was derived from soil polygon units at six map scales,namely,1:50 000(C5),1:200 000(D2),1:500 000(P5),1:1 000 000(N1),1:4 000 000(N4) and 1:14 000 000(N14),in the Taihu Region of China.Both soil unit formats were used for regional SOC pool simulation with a De Nitrification-DeC omposition(DNDC) process-based model,which spans the time period from 1982 to 2000 at the six map scales.Four indices,namely,soil type number(STN),area(AREA),average SOC density(ASOCD) and total SOC stocks(SOCS) of surface paddy soils that were simulated by the DNDC,were distinguished from all these soil polygon and grid units.Subjecting to the four index values(IV) from the parent polygon units,the variations in an index value(VIV,%) from the grid units were used to assess its dataset accuracy and redundancy,which reflects the uncertainty in the simulation of SOC pools.Optimal soil grid unit resolutions were generated and suggested for the DNDC simulation of regional SOC pools,matching their respective soil polygon unit map scales.With these optimal raster resolutions,the soil grid units datasets can have the same accuracy as their parent polygon units datasets without any redundancy,when VIV < 1% was assumed to be a criterion for all four indices.A quadratic curve regression model,namely,y = – 0.80 × 10^(–6)x^2 + 0.0228 x + 0.0211(R^2 = 0.9994,P < 0.05),and a power function model R? = 10.394?^(0.2153)(R^2 = 0.9759,P < 0.05) were revealed,which describe the relationship between the optimal soil grid unit resolution(y,km) and soil polygon unit map scale(1:10 000x),the ratio(R?,%) of the optimal soil grid size to average polygon patch size(?,km^2) and the ?,with the highest R^2 among different mathematical regressions,respectively.This knowledge may facilitate the grid partitioning of regions during the investigation and simulation of SOC pool dynamics at a certain map scale,and be referenced to other landscape polygon patches' mesh partition.

Modeling the radiometric imaging process of weld pool

In the vision monitoring or controlling the arc welding process, it is a prerequisite to get a clear image of weld pool. However, the disturbance of arc radiation makes imaging of weld pool difficult and optical filters are usually used to improve the image quality. In this paper, a radiometric imaging model is established to investigate the influence of the filter on the image quality of the weld pool, in which the spectral distribution of weld pool radiation, the spectral transmittance of the filter, the spectral sensitivity of the camera are all considered. With the proposed model, the influence of the factors on weld pool imaging can be inferred and the selection of optical filters is discussed.

Mechanism of Silurian Hydrocarbon Pool Formation in the Tarim Basin

There are three formation stages of Silurian hydrocarbon pools in the Tarim Basin. The widely distributed asphaltic sandstones in the Tazhong （central Tarim） and Tabei （northern Tarim） areas are the results of destruction of hydrocarbon pools formed in the first-stage, and the asphaltic sandstones around the Awati Sag were formed in the second-stage. The hydrocarbon migration characteristics reflected by the residual dry asphalts could represent the migration characteristics of hydrocarbons in the Silurian paleo-pools, while the present movable oil in the Silurian reservoirs is related to the iater-stage （the third-stage） hydrocarbon accumulation.

Deep Neural Network with Strip Pooling for Image Classification of Yarn-Dyed Plaid Fabrics

Historically,yarn-dyed plaid fabrics(YDPFs)have enjoyed enduring popularity with many rich plaid patterns,but production data are still classified and searched only according to production parameters.The process does not satisfy the visual needs of sample order production,fabric design,and stock management.This study produced an image dataset for YDPFs,collected from 10,661 fabric samples.The authors believe that the dataset will have significant utility in further research into YDPFs.Convolutional neural networks,such as VGG,ResNet,and DenseNet,with different hyperparameter groups,seemed themost promising tools for the study.This paper reports on the authors’exhaustive evaluation of the YDPF dataset.With an overall accuracy of 88.78%,CNNs proved to be effective in YDPF image classification.This was true even for the low accuracy of Windowpane fabrics,which often mistakenly includes the Prince ofWales pattern.Image classification of traditional patterns is also improved by utilizing the strip pooling model to extract local detail features and horizontal and vertical directions.The strip pooling model characterizes the horizontal and vertical crisscross patterns of YDPFs with considerable success.The proposed method using the strip pooling model(SPM)improves the classification performance on the YDPF dataset by 2.64%for ResNet18,by 3.66%for VGG16,and by 3.54%for DenseNet121.The results reveal that the SPM significantly improves YDPF classification accuracy and reduces the error rate of Windowpane patterns as well.

Evaporation Erosion During the Relay Contact Breaking Process Based on a Simplified Arc Model

Evaporation erosion of the contacts is one of the fundamental failure mechanisms for relays. In this paper, the evaporation erosion characteristics are investigated for the copper contact pair breaking a resistive direct current （dc） 30 V/10 A circuit in the air. Molten pool simulation of the contacts is coupled with the gas dynamics to calculate the evaporation rate. A simplified arc model is constructed to obtain the contact voltage and current variations with time for the prediction of the current density and the heat flux distributions flowing from the arc into the contacts. The evaporation rate and mass variations with time during the breaking process are presented. Experiments are carried out to verify the simulation results.

Weld pool boundary and weld bead shape reconstruction based on passive vision in P-GMAW

A passive visual sensing system is established in this research, and clear weld pool images in pulsed gas metal arc welding （ P-GMA W） can be captured with this system. The three-dimensional weld pool geometry, especially the weld height, is not only a crucial factor in determining workpiece mechanical properties, but also an important parameter for reflecting the penetration. A new three-dimensional （3D） model is established to describe the weld pool geometry in P-GMAW. Then, a series of algorithms are developed to extract the model geometrical parameters from the weld pool images. Furthermore, the method to reconstruct the 3 D shape of weld pool boundary and weld bead from the two-dimensional images is investigated.

RECONSTRUCTION OF WELD POOL SURFACE BASED ON SHAPE FROM SHADING

A valid image-processing algorithm of weld pool surface reconstruction according to an input image of weld pool based on shape from shading （SFS） in computer vision is presented. The weld pool surface information is related to the backside weld width, which is crucial to the quality of weld joint. The image of weld pool is recorded with an optical sensing method. Firstly, the reflectance map model, which specifies the imaging process, is estimated. Then, the algorithm of weld pool surface reconstruction based on SFS is implemented by iteration scheme and speeded by hierarchical structure. The results indicate the accuracy and effectiveness of the approach.

Predicting dynamics of soil organic carbon mineralization with a double exponential model in different forest belts of China

The dynamics of soil organic carbon （SOC） was analyzed by using laboratory incubation and double exponential model that mineralizable SOC was separated into active carbon pools and slow carbon pools in forest soils derived from Changbai and Qilian Mountain areas. By analyzing and fitting the CO2 evolved rates with SOC mineralization, the results showed that active carbon pools accounted tor 1.0% to 8.5% of SOC with an average of mean resistant times （MRTs） for 24 days, and slow carbon pools accounted for 91% to 99% of SOC with an average of MRTs for 179 years. The sizes and MRTs of slow carbon pools showed that SOC in Qilian Mountain sites was more difficult to decompose than that in Changbai Mountain sites. By analyzing the effects of temperature, soil clay content and elevation on SOC mineralization, results indicated that mineralization of SOC was directly related to temperature and that content of accumulated SOC and size of slow carbon pools from Changbai Mountain and Qilian Mountain sites increased linearly with increasing clay content, respectively, which showed temperature and clay content could make greater effect on mineralization of SOC.

Mathematical analysis of the role of recoil pressure in weld pool dynamics during laser-MIG hybrid welding

A mathematical model was established to simulate the weld pool development and dynamic process in stationary iaser-MlG hybrid welding. Surface tension and buoyancy were considered to calculate liquid metal flow patter, moreover, typical phenomena of MIG welding, such as filler droplets impinging weld pool, electromagnetic force in the weld pool, and typical phenomena of laser beam welding, such as recoil pressure, Inverse Bremsstrahlung absorption, Fresnel absorption were all considered in the model. The laser beam and arc couple effect were introduced into this model by the plasma width during hybrid welding. The role of recoil pressure in the weld formation was discussed. Transient weld pool shape and complicated liquid metal velocity distribution from two kinds weld pool to an unified weld pool were calculated. The simulated weld bead geometry with consideration recoil pressure was in good agreement with experimental measurement.

EPC Pool组网下PTN网络配置方案

组建EPC Pool后,当EPC发生故障时S1-Flex需进行切换,通过分析EPC与PTN落地设备的对接配置方案、LTE业务的转发路径、PTN系统的L2/L3与纯L3路由发布和L3 VPN的业务模型,探讨城域网L2/L3与纯L3设备和省干落地设备与纯L3设备间的L3 VPN路由配置方案,实现PTN系统与EPC Pool的协同配合,进而提高PTN和LTE业务安全性。

高质量发展视角下新阶段水利人才队伍建设机制研究

新阶段水利高质量发展亟须与之相适配的人才队伍,专业技术人才是推动新阶段水利高质量发展的骨干力量。从高质量发展视角出发,基于人力资本理论,搭建跨边界专业技术人才池,集聚并储备行业发展所需的关键人才,并从引进、培养、使用、评价、流动、激励全链条创新人才发展模式。基于灰色模型预测了人才需求特点,结合人力资本理论构建了跨边界人才池的开发机制和实施路径。结果表明:水利人才分布的空间异质性问题将持续存在,集聚并储备行业关键人才需要构建跨边界人才池;应通过内部培养和外部引进双轮驱动等措施满足行业人才需求,创新人才发展模式,从而在强化宏观调控的基础上实现人才的统筹调配、跨界蓄用与动态共享。

New model of body force in electromagnetic stirring gas tungsten-arc welding

After measuring arc electrical current density distribution in gas tungsten arc welding(GTAW) with a probe method, the new expression of body force and model of LD10CS aluminum alloy weld pool are put forward for the first time in GTAW with additional longitudinal magnetic field controlling. The influence of additional longitudinal magnetic field on body force is discussed by electromagnetic principle. This study provides the basis to study fluid flow of the weld pools and arc welding technique with electromagnetic controlling. [

Penetration Estimation of GMA Backing Welding Based on Weld Pool Geometry Parameters

Penetration estimation is a prerequisite of the automation of backing welding based on vision sensing technology. However, the arc interference in welding process leads to the difficulties of extracting the weld pool characteristic information, which brings great challenges to the penetration estimation. At present, most researches focus on the extraction of weld pool geometry parameters, and the visual sensing systems are complex in structure and complicated in the image processing algorithms. The research of penetration estimation based on weld pool geometry parameters is still in the exploratory stage. The purpose of this paper is to research the relationship between the weld pool geometry parameters and the penetration during backing welding and to estimate penetration using the weld pool geometry parameters. A passive vision sensing test system for gas metal arc (GMA) backing welding was established. An image processing algorithm was developed to extract the weld pool geometry parameters, namely, the area, maximum width and length, half-length, length-width ratio and advancing contact angle (simplified as AWP, MWWP, MLWP, HLWP, LWR and ACA, respectively). The corresponding relationships between the weld pool geometry parameters and the penetration state were explored by analysing their changes with the welding current and speed. The distribution of the weld pool geometry parameters corresponding to penetration was determined. When the AWP of the weld pool is within a certain range and the values of LWR and ACA are close to their maximum and minimum respectively, the penetration is in good condition. A mathematical model with the weld pool geometry parameters as independent variables and the back-bead width (the indicator of the penetration state) as a dependent variable was established based on multivariable linear regression analysis, and relevant statistical tests were carried out. Multivariable linear regression equations for the weld pool geometry parameters and the back-bead width were deduced according to the variations in the current and speed, and the equations can be used to estimate the penetration of backing welding. The study provides a solution to penetration estimation of GMA backing welding based on automatic vision sensing.

Evaluating health care financing in a highly decentralized Beveridge model

The Finnish health care system is financed in a highly decentralized manner. In the tax-financed Beveridge model each municipality is responseble for financing and organizing health care services for its residents. This paper examined the annual incidence and treatment costs of three cost-intensive DRG-groups, and all DRG-groups together. The objective was to estimate municipal level predictions on the incidence of new illness cases and their associated costs, and to analyze whether there was greater uncertainty in anticipated specialized health care costs in municipalities with smaller populations. The dataset comprised of longitudinal hospital utilization and discharge data from Hospital Discharge Registers. The expected annual variation of illness cases and costs was assessed with respect to 95% confidence intervals estimated for each morbidity group and municipality. The results indicated that the costs of the selected morbidity groups fluctuated in a completely uncontrollable manner in municipalities with small populations. As the median size of Finnish municipalities is less than 6000, the inability to anticipate periodic health care costs constitutes an extensive financial problem and calls for the establishment of larger regional units and funding pools.

基于视觉注意VGGNet的中厚板低碳钢多层多道熔池分类模型

重大装备制造中厚板机器人多层多道焊(multi-layer and multi-pass welding,MLMPW)一直是热点和难点,而实现机器人MLMPW的核心是对其熔池的获取、监控并分类.为了提高MLMPW的自动化和智能化,有必要开发一个熔池图像在线分类系统.针对焊接过程中的熔池图像提出了一种新的MLMPW熔池分类方法——基于视觉注意的(SENet)VGGNet熔池分类方法.为了提高效率和精度,引入迁移学习中的预训练模型到网络训练过程中.因为针对中厚板多层多道熔池研究较少,导致熔池公开数据集较少,为了应对这一问题,需要对数据集进行增广.结果表明,提出的模型可快速有效的对七类MLMPW熔池进行准确分类,预测精度可达到98.39%.

小熔池激光沉积制造薄壁件沉积宽度的模型预测及试验研究

将激光沉积制造的热物理过程与薄壁件的几何特性相结合,基于层间沉积过程中的能量守恒关系建立了可以适配于小熔池激光沉积制造薄壁件沉积宽度的预测模型。该模型详细阐述了沉积宽度与激光功率、扫描速度与送粉速率之间的关系。利用Ti–6Al–4V(TC4)粉末沉积制备了多组样品来进行预测模型的验证,结果表明,该模型可以准确地预测不同工艺参数下薄壁件的沉积宽度,提高了试验参数匹配的准确性与效率,并为小熔池激光沉积制造工艺成形精度控制奠定了理论基础。

Study on Factors Effecting Weld Pool Geometry of Pulsed Current Micro Plasma Arc Welded AISI 304L Austenitic Stainless Steel Sheets Using Statistical Approach

Pulsed current Micro Plasma Arc Welding is used to joint thin sheets of AISI 304L sheets, which are used in manufacturing of metallic bellows and diaphragms. In this article the effects of pulsing current parameters on weld pool geometry namely front width, back width, front height and back height of pulsed current micro plasma arc welded AISI 304L stainless steel sheets was analyzed. Four factors, five levels, central composite design was used to develop mathematical models, incorporating pulsed current parameters and weld pool geometry. The mathematical models have been developed by Response Surface Method. The adequacy of the models was checked by ANOVA technique. Variation of output responses with input process variables are discussed. By using the developed mathematical models, weld pool geometry parameters can be predicted.