Retrospective analysis of two northern California wild-land fires via Landsat five satellite imagery and Normalized Difference Vegetation Index (NDVI)

Wild-land fires are a dynamic and destructive force in natural ecosystems. In recent decades, fire disturbances have increased concerns and awareness over significant economic loss and landscape change. The focus of this research was to study two northern California wild-land fires: Butte Humboldt Complex and Butte Lightning Complex of 2008 and assessment of vegetation recovery after the fires via ground based measurements and utilization of Landsat 5 imagery and analysis software to assess landscape change. Multi-temporal and burn severity dynamics and assessment through satellite imagery were used to visually ascertain levels of landscape change, under two temporal scales. Visual interpretation indicated noticeable levels of landscape change and relevant insight into the magnitude and impact of both wild-land fires. Normalized Burn Ratio (NBR) and delta NBR (DNBR) data allowed for quantitative analysis of burn severity levels. DNBR results indicate low severity and low re-growth for Butte Humboldt Complex “burned center” subplots. In contrast, DNBR values for Butte Lightning Complex “burned center” subplots indicated low-moderate burn severity levels.

Passive Localization Using Time Difference of Arrival and Frequency Difference of ArrivalWC

In order to improve the accuracy and engineering feasibility of four-Satellite localization system, the frequency difference measurement is introduced to the four-Satellite TDOA (Time Difference of Arrival) localization algorithm. The TDOA/FDOA (Frequency Difference of Arrival) localization algorithm is used to optimize the GDOP (geometric dilution of precision) of four-Satellite localization. The simulation results show that the absolute position measurement accuracy has little influence on TDOA/FDOA localization accuracy as compared with TDOA localization. Under the same conditions, TDOA/FDOA localization has better accuracy and its GDOP shows more uniform distribution in diamond configuration case. The localization accuracy of four-Satellite TDOA/FDOA is better than the localization accuracy of four-Satellite TDOA.

Nodulation and Fixed Atmospheric Nitrogen of Some Local Lima Bean (<i>Phaseolus lunatus</i>L.) Cultivars Grown in a Coastal Savannah Environment

Legumes, in symbiotic association with Rhizobia, are able to fix atmospheric N. Six local lima bean (Phaseolus lunatus) cultivars were grown under rainfed conditions in a coastal savannah environment. Objectives of the study were to evaluate the nodulation and fixed atmospheric N levels of the six local lima bean cultivars using both the 15N isotope dilution method and N difference method (NDM). The linear relationship between fixed atmospheric N estimated using the 15N isotope dilution method and NDM, was also assessed. The experiment was arranged in a randomized complete block design (RCBD) in three replicates with seven treatments, comprising six lima bean cultivars (B1, B2, B3, B4, B5 and B6) and the early maturing local maize variety, “Doke”, as the reference crop. Total, effective nodules (EN) and non-effective nodules (NEN) were determined on 42 and 56 days after planting (DAP). The 15N isotopic dilution method and NDM were used to quantify the fixed atmospheric N by the lima bean cultivars on 60 DAP. Effective root nodules per plant (EN) on 56 DAP ranged from 0.71 to 1.22, with the lima bean cultivar B4 having the highest value and cultivars B2 and B5 having the lowest value of EN, respectively. Similarly on 56 DAP, the lima bean cultivar B4 had the highest NEN value while cultivars B1, B2 and B5 had the lowest NEN value of 0.71 per plant. The mean fixed atmospheric N was 8.98 kg&middotha-1, based on the 15N isotope dilution method, which was lower than 10.13 kg&middotha-1 of fixed atmospheric N determined using NDM. The linear relationship between fixed atmospheric N estimated using the 15N isotope dilution method and that estimated using the NDM, was positive but of average quality as the R2 value was 0.56. Consequently, the linear model obtained from this relationship is moderate as 56% of the data used for the linear regression analysis were accounted for by the linear regression model developed. However, NDM could be used for fast screening to select lima bean cultivars for a more detailed study to identify cultivars with promising fixed atmospheric N capabilities. Generally, results of the study provide opportunities for designing breeding and other agronomic programmes for enhancing the productivity and N-fixing capacity of local lima beans in the coastal savannah environment.

CONVERGENCE ANALYSIS OF MIXED VOLUME ELEMENT-CHARACTERISTIC MIXED VOLUME ELEMENT FOR THREE-DIMENSIONAL CHEMICAL OIL-RECOVERY SEEPAGE COUPLED PROBLEM

The physical model is described by a seepage coupled system for simulating numerically three-dimensional chemical oil recovery, whose mathematical description includes three equations to interpret main concepts. The pressure equation is a nonlinear parabolic equation, the concentration is defined by a convection-diffusion equation and the saturations of different components are stated by nonlinear convection-diffusion equations. The transport pressure appears in the concentration equation and saturation equations in the form of Darcy velocity, and controls their processes. The flow equation is solved by the conservative mixed volume element and the accuracy is improved one order for approximating Darcy velocity. The method of characteristic mixed volume element is applied to solve the concentration, where the diffusion is discretized by a mixed volume element method and the convection is treated by the method of characteristics. The characteristics can confirm strong computational stability at sharp fronts and it can avoid numerical dispersion and nonphysical oscillation. The scheme can adopt a large step while its numerical results have small time-truncation error and high order of accuracy. The mixed volume element method has the law of conservation on every element for the diffusion and it can obtain numerical solutions of the concentration and adjoint vectors. It is most important in numerical simulation to ensure the physical conservative nature. The saturation different components are obtained by the method of characteristic fractional step difference. The computational work is shortened greatly by decomposing a three-dimensional problem into three successive one-dimensional problems and it is completed easily by using the algorithm of speedup. Using the theory and technique of a priori estimates of differential equations, we derive an optimal second order estimates in 12 norm. Numerical examples are given to show the effectiveness and practicability and the method is testified as a powerful tool to solve the important problems.

Design of a Simulator for Enhanced Oil Recovery Process Using a Nigerian Reservoir as a Case Study

This study involves the applications of different numerical techniques in a more general way to the design of a simulator for an enhanced oil recovery process with surfactant assisted water flooding. The data from a hypothetical oil well and a Nigerian oil well were used for the validation of the simulator. The process is represented by a system of nonlinear partial differential equations: the continuity equation for the transport of the components and Darcy’s equation for the phase flow. The orthogonal collocation, finite difference and coherence theory techniques were used in solving the equations that characterized the multidimensional, multiphase and multicomponent flow problem. Matlab computer programs were used for the numerical solution of the model equ- ations. The predicted simulator, obtained from the resulting numerical exercise confers uncondi- tional stability and more insight into the physical reservoir description. The results of the ortho- gonal collocation solution were compared with those of finite difference and coherence solutions. The results indicate that the concentration of surfactants for orthogonal collocation show more features than the predictions of the coherence solution and the finite difference, offering more opportunities for further understanding of the physical nature of the complex problem. We have found out that the partition of the three components between the two-phases determines other physical property data and hence the oil recovery. The oil recovery for the Nigerian oil reservoir is higher than the recovery predicted for the hypothetical crude. The displacement mechanism for the multicomponent and multiphase system is stable in the Nigerian oil reservoir due to the mod- erate value of the oil/water viscosity instead of the hypothetical reservoir with high value of oil/water ratio.

考虑桩土间黏滑机制的桩基沉降动态特性研究

基于桩基运动控制方程,对荷载作用下的桩基沉降动态特性进行了研究。首先,考虑桩土间黏滞与滑动两种接触状态,建立了一种考虑侧阻软化及侧阻恢复的桩土相互作用模型;然后采用该模型及修正三折线模型分别模拟桩与桩侧土以及桩端土间的相互作用,结合有限差分法建立了考虑桩土间黏滑机制的桩基沉降分析方法;最后,基于建立的桩基受荷沉降分析方法,研究了桩基沉降的黏滑动态特性以及桩身的力学特性,并讨论了桩土相互作用模型中的参数对桩基沉降动态特性的影响。结果表明:当桩顶荷载接近桩基单级加载极限值,桩基沉降表现出黏滞位移与快速滑动位移交替的动态特性;桩身力学响应表现出加载路径相关性,与单级加载相比,分级加载时桩侧摩阻力能得到更好发挥,桩基极限承载力更高;提出的分析方法能够较好地模拟桩基静载试验沉降过程。

多执行器载荷差异储能均衡系统特性

针对阀控多执行器复合作业系统节流损失大、动势能浪费严重等问题,提出一种多执行器载荷差异储能均衡原理。首先对多执行器系统功率分配特性进行分析,明确了载荷差异产生节流损失的原因是动力源压力与最大负载相匹配,导致其他执行器控制阀产生过大的压力损失。然后建立了载荷储能均衡液压挖掘机联合仿真模型。并设计电液储能单元控制各执行器进油腔的压力相等,从而消除执行器载荷差异造成的节流损失。在动臂、铲斗同时动作时,与流量匹配系统相比,所提系统节流损失降低达75%,系统效率提升39%;同时,电液储能单元实现了传统压力补偿器的压差调控功能,显著提升了系统运行平稳性。

基于可变高增压方式的航空活塞发动机变海拔工作特性仿真研究

以一台直列四冲程压燃式航空活塞发动机为研究机型,通过GT-Power构建一维热力学模型,首先对比研究了不同海拔下固定截面增压(fixed geometry turbocharger,FGT)、可变几何截面增压(variable geometry turbocharger,VGT)和两级可变几何截面增压(twinvariable geometry turbocharger,TVGT)对发动机性能的影响;然后基于搭建的TVGT增压系统,探究了高、低压级VGT叶片开度对发动机变海拔条件下工作特性的影响。结果表明:在不同海拔和转速工况下,发动机匹配TVGT增压系统后,其海拔适应性更佳。针对TVGT系统,在不同海拔下,当高压级VGT叶片开度位于0.2~0.4范围内,低压级VGT叶片开度位于0.6~0.8范围内时可以获得较高的动力性及经济性。通过对高、低压级VGT叶片开度的优化,在巡航工况转速3397 r/min时可在6000 m海拔下实现106.8%的功率恢复目标,可满足发动机对高海拔工作运行的功率恢复要求。

黄河下游近期持续冲刷过程中床沙粗化特性分析

床沙组成的变化影响悬沙沿程恢复及河床阻力变化。本文基于黄河下游7个水文站1999—2020年的实测床沙资料,计算了各水文断面不同粒径组床沙占比的年际变化,分析了近二十年持续冲刷过程中不同河型河段床沙的时空粗化特性,讨论了河床冲淤过程对床沙粗化的影响。从时间来看,小浪底水库运用后,不同时期床沙的粗化特点不同,拦沙初期(2000—2006年)急剧粗化,拦沙后期(2007—2020年)粗化放缓,高村站及上游各站床沙呈波动粗化,高村站以下则变化不大,且粗化程度最强处由游荡段向下游过渡段转移;从空间来看,床沙沿程细化,游荡段以极粗沙为主,过渡段以粗沙和极粗沙为主,弯曲段的中细沙不可忽视。拦沙初期各河段床沙组成的调整表现为中细均冲;拦沙后期则表现为中粗均冲,极粗沙占比增大,利津以上各站细沙占比不足5%,对悬沙的补给受限,中沙和粗沙仍经受冲刷,极粗沙对相应悬沙有较好补给作用。河段汛后床沙中值粒径与河床累计冲刷量呈良好的幂函数正相关关系,但拦沙后期床面已粗化到相当程度,河床冲淤对床沙粗化的影响受限。研究结果有助于掌握近期整个黄河下游床沙的粗化现状及预测下游河道冲淤变形规律。

新型贫化剂强化回收渣含铜的研究

为强化铜渣贫化回收渣含铜,设计了一种强化铜渣贫化的还原剂。采用HSC 6.0热力学软件计算对比了新型贫化剂与无烟煤、黄铁矿等常用贫化剂贫化熔炼渣回收铜锍的反应,并以某冶炼厂熔炼渣为原料进行试验并验证了新型贫化剂的强化作用。热力学计算结果表明,新型贫化剂还原铜渣(主要成分为Fe_(2) SiO_(4)和Fe_(3) O_(4))的效果优于无烟煤和黄铁矿。试验结果表明,采用无烟煤、黄铁矿、新型贫化剂三种还原剂单独贫化回收渣含铜时,铜的回收率分别为30.83%、52.50%、66.67%。新型贫化剂能够强化回收渣含铜,有望为铜渣高效贫化并提高无烟煤等传统化石能源贫化铜渣利用率提供借鉴。

疼痛管理模式下不同绷带包扎时间对全膝关节置换术后患者早期功能恢复的影响

目的研究疼痛管理模式下不同绷带包扎时间对全膝关节置换术后患者早期功能恢复的影响。方法选择2022年6月至2023年5月单侧全膝关节置换手术(TKA)患者80例,根据弹力绷带使用时间,24 h为对照组(40例),48 h为研究组(40例);观察两组围手术期术侧下肢的周径、膝关节功能、伤口并发症、相关不良反应,随访期间步速、步频、步幅。结果术后7 d、14 d大腿、膝关节、小腿周径均短于对照组;术后7 d、30 d膝关节活动度(ROM)屈、伸均大于对照组,膝关节功能评分(HSS)高于对照组;术后3个月两组均出现好转,研究组步速、步频、步幅均高于对照组(P<0.05)。两组伤口并发症以及相关不良反应之间无统计学差异(P>0.05)。结论全膝关节置换术后患者在疼痛管理模式下,使用48 d弹力绷带,能够减轻术肢肿胀,增加肢体的屈伸活动,有利于膝关节功能恢复。

SPARSE RECOVERY BASED ON THE GENERALIZED ERROR FUNCTION

In this paper,we offer a new sparse recovery strategy based on the generalized error function.The introduced penalty function involves both the shape and the scale parameters,making it extremely flexible.For both constrained and unconstrained models,the theoretical analysis results in terms of the null space property,the spherical section property and the restricted invertibility factor are established.The practical algorithms via both the iteratively reweighted■_(1)and the difference of convex functions algorithms are presented.Numerical experiments are carried out to demonstrate the benefits of the suggested approach in a variety of circumstances.Its practical application in magnetic resonance imaging(MRI)reconstruction is also investigated.

基于感官和化学分析技术解析不同产区酱酒风味特征

联合采用感官分析、香气活性成分定性与定量技术,对茅台镇和神农架产区酱酒的香气感官特征及香气组分特征进行解析。感官分析表明茅台镇酱酒主要表现为曲香、粮香、酱香等香气特征,神农架酱酒则主要表现为甜香、酱香、青草香、酸香等香气特征。采用香气萃取物稀释分析技术从2个产区酱香型白酒中筛选出133种挥发性物质(香气稀释因子≥2);基于多组分的定量结果结合香气活度值(odor activity value,OAV)与偏最小二乘判别分析,从2个产区酱酒中共挖掘出65个重要香气化合物(OAV>1)以及32个差异性化合物[即变量权重重要性排序(variable importance for the projection,VIP)≥1];进一步明确了2个不同产区酱酒的香气感官特征与香气化合物之间的联系。结果表明,与茅台镇酱酒感官特征相关的重要香气化合物主要包括2,3,5-三甲基吡嗪、2-乙基-3,5-二甲基吡嗪、2-乙基-5-甲基吡嗪、2,6-二甲基吡嗪、2-甲基丁酸乙酯、己酸乙酯、乳酸乙酯、γ-丁内酯、苯丙酸乙酯、异戊酸乙酯;与神农架酱酒感官特征相关的重要香气物质为甲硫醇、2,6-二乙基吡嗪、2-乙基-6-甲基吡嗪、3-甲硫基丙醛、香草醛、2,3-丁二酮、γ-壬内酯、3-羟基-2-丁酮、乙醛、乙缩醛、己醛、异戊醛。该研究通过剖析两类酱香型白酒的香气轮廓与风味特征,增进了对2个产区酱酒风味独特性的认识,为生产品质控制提供了参考和理论依据。

人工流产手术不同剂量利多卡因复合丙泊酚静脉麻醉镇痛效果及对术后恢复影响

目的:探究不同浓度利多卡因复合丙泊酚麻醉对人工流产手术者镇痛效果及安全性。方法:从本院2021年1月-2023年1月拟行人工流产者筛选100例,数字表法随机分为高浓度组、低浓度组各50例,分别采用丙泊酚复合2%或1%利多卡因宫颈旁阻滞麻醉,对比两组麻醉效果、疼痛评分(VAS)、血流动力学、炎症因子与不良反应发生率。结果:低浓度组意识清醒时间(4.7±0.8 min)、定向力恢复时间(6.1±0.6 min)均短于高浓度组(9.1±0.6 min、10.6±1.0 min),手术时间(12.4±0.4 min)、丙泊酚用量(106.6±3.4 mg)高于高浓度组(10.2±0.6 min、97.9±1.3 mg)、;两组清醒时平均动脉压(MAP)、心率(HR)水平均升高,但高浓度组(80.3±1.5 mmHg、82.8±1.2次/min)低于低浓度组(84.7±1.7 mmHg、86.3±0.8次/min);两组术后30min的VAS评分均降低且高浓度组(1.80±0.81分)低于低浓度组(5.02±0.89分),两组清醒时MAP、HR水平较麻醉前均升高且高浓度组低于低浓度组,术后10min两组TNF-α、IL-6水平较麻醉前升高,但高浓度组(34.35±3.11 pg/ml、24.93±2.65 pg/ml)低于低浓度组(50.25±2.95 pg/ml、50.50±2.74 pg/ml)(均P<0.05)。不良反应发生率高浓度组与低浓度组(26.0%、12.0%)无差异(P>0.05)。结论:2%利多卡因复合丙泊酚麻醉可提升人工流产镇痛效果,缩减手术时间与丙泊酚用量,减少手术麻醉对血流动力学、炎症反应的影响;1%利多卡因有助于促进意识恢复与定向力恢复,发生呼吸抑制、恶心呕吐、头晕等例数更少,有更高的安全性。

柳10断块沙三^(5)油藏开发技术政策研究

柳10断块沙三^(5)为复杂断块油藏,油砂体范围小,水驱控制程度低且以单向水驱为主,目前断块注采井网极不完善,采出程度仅14.2%,综合含水达到92.7%。急需调整开发技术政策,提高水驱开发效果。在三维地质建模的基础上,结合油藏数值模拟分析砂层的剩余油储量分布情况,剩余可采储量大于1×10^(4)t的小层有21个,柳10断块沙三^(5)油藏有一定的开采潜力。调整方案采用三角形七点法井网,生产井距控制在150~200m,生产压差控制在12-14MPa,单井注入量150m^(3)/d。利用14口老井,补充13口新井,层系纵向上划分为三段,以“加密井网,分段开采;先分后合,接替稳产”的方式进行开采。调整方案实施后,预计总体水驱控制程度可达61.4%,新建产能1.89×10^(4)t,预计增加可采储量20×10^(4)t,经济论证与评价指标达到了行业标准,有一定的盈利能力。

不同处理方式对胆道疾病患者外科手术后胃肠功能恢复的影响研究

外科手术后胃肠功能是否可以快速恢复关系到患者预后效果。为此探讨了不同处理方式给胆道疾病患者外科手术后胃肠功能恢复带来的影响。将80例胆道疾病患者分成试验1组和试验2组,常规术后处理是试验1组采取的处理方式,早期营养支持是试验2组采取的处理方式,观察患者术后胃肠功能恢复和预后效果。结果显示,从胃肠功能恢复时间方面来看,试验2组排便时间、进食时间、肠鸣音恢复时间和肛门排气时间均短于试验1组;从营养指标和免疫功能方面来看,试验2组患者各指标改善效果均优于试验1组,且并发症发生率低于试验1组,生活质量高于试验1组。研究发现,对于接受外科手术治疗的胆道疾病患者,需要采取正确的术后处理方式,早期进行营养支持,以加快胃肠功能恢复,改善预后。

基于PVT实验的凝析气藏衰竭开发采收率标定新方法

凝析气的等容衰竭实验与实际凝析气藏衰竭开发存在两点差异:实验初始压力为露点压力,而一般凝析气藏原始地层压力大于露点压力;等容衰竭实验中降压和产气分步进行,而实际为降压和产气同步进行。研究发现,以上两点差异对干气采收率预测影响不大,但会导致基于等容衰竭实验标定凝析油采收率严重偏低。为提高基于等容衰竭实验标定凝析油采收率预测精度,通过组合凝析气两相压降方程、凝析油产量方程及井流物标况体积定义式,并考虑地露压差的影响,建立一套基于等容衰竭实验标定定容凝析气藏衰竭开发采收率新方法。该方法在实际矿产应用中准确性较高,对于预测凝析气藏采收率具有重要指导意义。

The Characteristic Finite Difference Methods for Enhanced Oil Recovery Simulation and L^2 Estimates

A 2-dimensional, multicomponent, multiphase, and incompressible compositional reservoir simulator has been developed and applied to chemical flooding (surfactants, alcohol and polymers) and convergence analysis. The characteristic finite difference methods for 2-dimensional enhanced oil recovery can be described as a coupled system of nonlinear partial differential equations. For a generic case of the cross interference and bounded region, we put forward a kind of characteristic finite difference schemes and make use of thick and thin grids to form a complete set, and of calculus of variations, the theory of prior estimates and techniques. Optimal order estimates in L^2 norm are derived for the error in the approximate solutions. Thus we have thoroughly solved the well-known theoretical problem proposed by a famous scientist, J. Douglas, Jr.

RARE EARTH RECOVERY BY SUPPORTED LIQUID MEMBRANE

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某液压泵马达测试台功率回收系统研究及分析

随着液压泵等液压元件的发展趋向高压、高功率、高转速,液压元件测试台的功率也在不断提高,造成更多的能量消耗,因此试验台的功率回收至关重要。分析了电功率、机械补偿和液压补偿的功率回收系统方案,确定出液压泵马达测试台较为理想的功率回收系统形式。对选用的电功率回收系统通过AMESim软件建立了功率回收系统模型,对不同工况下电功率回收系统的回收率进行分析。