Pore throat structure heterogeneity and its effect on gas-phase seepage capacity in tight sandstone reservoirs:A case study from the Triassic Yanchang Formation,Ordos Basin

The microscopic heterogeneity of pore-throat structures in tight sandstone is a crucial parameter for understanding the transport mechanism of fluid flow.In this work,we firstly developed the new procedure to characterize the pore size distribution(PSD)and throat size distribution(TSD)by combining the nuclear magnetic resonance(NMR),cast thin section(CTS),and constant-rate mercury injection(CRMI)tests,and used the permeability estimated model to verify the full-scale PSD and TSD.Then,we respectively analyzed the fractal feature of the pore and throat,and characterized the heterogeneity of pores and throats.Finally,we elaborated the effect of the pore and throat heterogeneity on the gas-phase seepage capacity base on the analysis of the simple capillary tube model and gas-flooding experiment.The results showed that(1)The PSD and TSD of the tight sandstone sample ranged from 0.01 to 10 mm and from 0.1 to 57 mm,respectively,mainly contributed by the micropores and mesopores.Meanwhile,the permeability estimated by the PSD and TSD was consistent with the experimental permeability,and relative error was lower than 8%.(2)The PSD and TSD exhibited multifractal characteristics,and singularity strength range,Δα,could be used as the indicator for characterizing the heterogeneity of pore and throat.Furthermore,the throat of the sample showed stronger heterogeneity than that the pore.(3)The throats played an important role for the fluid transport in the tight sandstone,and the effect of the throat heterogeneity on the gas-phase seepage capacity was different under the lower and higher injection pressure.The macropores and micropores maybe respectively become the preferential migration pathways at the lower and higher injection pressure.In the end,the identification plate was established in our paper,and could be described the relationship among the throat heterogeneity,injection pressure,permeability and flow path of the gas phase in the tight sandstone.

Impact of product heterogeneity and soft budget constraint on excess capacity in Chinese energy industry based on the duopoly model

Chinese energy industries are facing serious problems such as excess capacity,homogeneous product,and soft budget constraint.This paper provides a duopoly model to investigate the influence of heterogeneity and soft budget constraint on production capacity decision and internal action mechanism,respectively,under Cournot and Bertrand competitions,which reveals the formation mechanism of excess capacity.We conclude that excess capacity would exist when the products are not wholly heterogeneous under Cournot competition,and the higher level of the soft budget constraint or the more homogeneous the products are,the worse the excess capacity will be.The insufficient capacity would exist provided that products are not wholly heterogeneous under Bertrand competition,and the higher level of soft budget constraint or the more homogeneous the products are,the more insufficient capacity will be.Both soft budget constraint and product heterogeneity mutually affect to decision-making of capacity and output.

Government intervention model based on behavioral heterogeneity for China’s stock market

Active government intervention is a striking characteristic of the Chinese stock market.This study develops a behavioral heterogeneous agent model(HAM)comprising fundamentalists,chartists,and stabilizers to investigate investors’dynamic switching mechanisms under government intervention.The model introduces a new player,the stabilizer,into the HAM as a proxy for the government.We use the model to examine government programs during the 2015 China stock market crash and find that it can replicate the dynamics of investor sentiment and asset prices.In addition,our analysis of two simulations,specifically the data-generating processes and shock response analysis,further corroborates the key conclusion that our intervention model not only maintains market stability but also promotes the return of risk asset prices to their fun-damental values.The study concludes that government interventions guided by the new HAM can alleviate the dilemma between reducing price volatility and improving price efficiency in future intervention programs.

Study on QoS and Communications Capacity in Heterogeneous Network Convergence

To provide any subscriber from anywhere at anytime with services that have both secured Quality of Service(QoS) and simultaneous expansion of network coverage and communications capacity is a key problem that has to be considered and solved in heterogeneous network convergence.Key technologies for a secured QoS and communications capacity analysis under heterogeneous environment are important subjects for research.Key technologies for a secured QoS are mainly on radio resource management algorithms covering Call Admission Control(CAC) algorithm,vertical handover algorithm,heterogeneous resource allocation algorithm and network selection algorithm.The applications of a novel multi-hop in heterogeneous convergence system serve the purposes of network coverage expansion,transmission power reduction,system communication capacity and throughput increase.

Calibrating HCM model for roundabout entry capacity under heterogeneous traffic

Roundabout is a channelized intersection where traffic moves around a central island,clockwise for leftside driving and anti-clockwise for right-side driving.Efficiently designed roundabouts can handle traffic very smoothly without causing any delay.The capacity of roundabouts used to be calculated by the weaving theory in India.However,calculation of the entry capacity in the recent literature is based on critical gaps and follow-up times,and the Highway Capacity Manual of US(HCM2010)provides an equation to estimate the entry capacity of a roundabout by using the flow in passenger car unit per hour(PCU/h),critical gaps and follow-up times at the entry section.In order to examine whether the HCM equation applies to Indian traffic condition or not,we collected data from five roundabouts in India in this study.Relevant data were extracted/estimated to calibrate parameters of the HCM equation.The PCU for a vehicle was estimated on the basis of lagging headway and width of the vehicle,and the critical gap value for a vehicle was estimated by minimizing the sum of absolute difference in a gap with respect to the highest rejected and accepted gaps.Results show that the critical gap values obtained under heterogeneous traffic conditions are much lower than those given in the literature for homogeneous traffic conditions.In addition,the modified HCM equation based on the critical gap values was verified using the field data taken during the formation of a continuous and stable queue at the entry of a roundabout.It was found that a multiplicative adjustment factor needs to be calculated for different sizes of roundabouts to ensure the adjusted HCM equation represents well the traffic condition prevailing in developing countries like India.A test conducted at another roundabout validated that the entry capacity estimated from the calibrated and adjusted HCM model was consistent with the field entry capacity,and the calibrated and adjusted HCM model could predict the entry capacity of an approach to a roundabout quite accurately.

A Diffusive Predator-Prey Model with Spatially Heterogeneous Carrying Capacity

We study local dynamics of a diffusive predator-prey model in a spatially heterogeneous environment,where intrinsic growth rate of the prey is spatially ho-mogeneous,whereas carrying capacity of the habitat is spatially inhomogeneous.In comparison with the existing predator-prey models,the stability of semi-trivial steady state of this model displays distinct properties.For example,for certain intermediate ranges of the death rate of the predator,the semi-trivial steady state can change its stability at least once as the dispersal rate of the prey varies from small to large,while the stability of the semi-trivial steady state is immune from the dispersal rate of the predator.

Atmospheric oxidizing capacity in autumn Beijing:Analysis of the O_(3) and PM_(2.5) episodes based on observation-based model

Atmospheric oxidizing capacity(AOC)is the fundamental driving factors of chemistry process(e.g.,the formation of ozone(O_(3))and secondary organic aerosols(SOA))in the troposphere.However,accurate quantification of AOC still remains uncertainty.In this study,a comprehensive field campaign was conducted during autumn 2019 in downtown of Beijing,where O_(3) and PM_(2.5) episodes had been experienced successively.The observation-based model(OBM)is used to quantify the AOC at O_(3) and PM_(2.5) episodes.The strong intensity of AOC is found at O_(3) and PM2.5 episodes,and hydroxyl radical(OH)is the dominating daytime oxidant for both episodes.The photolysis of O_(3) is main source of OH at O_(3) episode;the photolysis of nitrous acid(HONO)and formaldehyde(HCHO)plays important role in OH formation at PM_(2.5) episode.The radicals loss routines vary according to precursor pollutants,resulting in different types of air pollution.O_(3) budgets and sensitivity analysis indicates that O_(3) production is transition regime(both VOC and NOx-limited)at O3 episode.The heterogeneous reaction of hydroperoxy radicals(HO_(2))on aerosol surfaces has significant influence on OH and O_(3) production rates.The HO_(2) uptake coefficient(γHO_(2))is the determining factor and required accurate measurement in real atmospheric environment.Our findings could provide the important bases for coordinated control of PM_(2.5) and O_(3) pollution.

Undrained seismic bearing capacity of strip footing adjacent to a heterogeneous excavation

The analysis of the bearing capacity of strip footings sited near an excavation is critical in geotechnics.In this study,the effects of the geometrical features of the excavation and the soil strength properties on the seismic bearing capacity of a strip footing resting on an excavation were evaluated using the lower and upper bounds of the finite element limit analysis method.The effects of the setback distance ratio(L/B),excavation height ratio(H/B),soil strength heterogeneity(kB/cu),and horizontal earthquake coefficient(kh)were analyzed.Design charts and tables were produced to clarify the relationship between the undrained seismic bearing capacity and the selected parameters.

HETEROGENEITY, NONLINEARITY AND ENDOGENOUS MARKET VOLATILITY

这份报纸试图与异构的代理人在行为模型的解释力量上贡献文学。在场的作者是由动态噪音的非线性的确定的过程 buffeted 的一个新非线性的结构的证券市场模型。外长的噪音与基本的值的 IID 正常革新的假设被介绍给模型以便调查吵闹的动力学怎么与确定的过程交往。市场由二种典型商人类型组成：合理信奉正统派基督教的人和固定地合理的商人由贪婪和害怕管理了。当关键参数被改变，在噪音和确定的元素之间的相互作用决定系统的进化进程。作者发现模型能产生动态的展览和非常 S&P500 类似于那些的统计性质索引的时间系列，例如轻快聚类，胖尾巴(leptokurtosis ) ，在方形、绝对的回来的自相关，更大的振幅，碰撞和水泡。作者也在我们的数据调查非线性的依赖结构。结果显示 GARCH 类型模型不能完全在我们的模仿的市场说明所有非线性，它与从真实市场的结果因此一致。看起来非线性的结构的模型是更有力的给满足的解释比传统的随机的途径出售行为。

植物乳杆菌和模仿葡萄球菌复配对发酵羊肉香肠理化性质、风味及多肽抗氧化能力的影响

本研究以植物乳杆菌(Lactobacillus plantarum)CD101和模仿葡萄球菌(Staphylococcus simulans)NJ201作为复配发酵剂制作发酵羊肉香肠,以不接菌自然发酵香肠为空白对照。通过测定两组pH值、色差、质构等理化指标,游离氨基酸、挥发性风味物质的种类与含量,测定从香肠中提取的多肽对1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基、2,2’-联氮双(3-乙基苯并噻唑啉-6-磺酸)(2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid),ABTS)阳离子自由基、羟自由基的清除能力,探究复配发酵剂对发酵羊肉香肠理化性质、风味及多肽抗氧化能力的改善作用。结果表明,植物乳杆菌CD101和模仿葡萄球菌NJ201复配发酵能够迅速降低羊肉香肠在发酵期间的pH值,提高香肠的安全性;提高羊肉香肠的亮度与色泽、硬度和咀嚼性,改善其品质;增加游离氨基酸总量、挥发性风味物质种类,提升羊肉香肠的风味;显著提高羊肉香肠多肽对DPPH自由基、ABTS阳离子自由基以及羟自由基的清除率,提升香肠多肽抗氧化活性。综上,接种发酵能对发酵羊肉香肠理化性质、风味及多肽的抗氧化能力均有明显改善。本研究能够为发酵肉制品的工业化生产提供理论依据。

京津冀城市群综合承灾能力时空异质性研究

基于2010—2020年京津冀城市群13个城市的调查数据,应用Kernel密度估计方法、空间自相关模型及Dagum基尼系数,分析不同时期京津冀城市群综合承灾能力时空动态演进分布格局及地区差异。结果表明:(1)在时间维度,2010—2020年京津冀城市群综合承灾能力总体呈现逐渐上升趋势,但京津冀城市群各市之间的承灾能力水平差距逐渐增大,区域整体呈现非均衡特征;(2)在空间维度,2010—2020年京津冀城市群综合承灾能力在空间分布上关联度较低,不存在显著的集聚或分散特征,但有局部地区产生聚集特点,属于“高-高”“低-低”空间聚集型城市较多,在此期间京津冀城市群综合承灾能力呈现空间集聚与空间分异并存;(3)京津冀城市群综合承灾能力的总体差异呈现上升趋势,北京-河北地区间差异最大,地区间差异是总体差异的主要来源。掌握京津冀城市群综合承灾能力的时空分布变化规律,并制订相应的防灾策略是京津冀城市群有效应对外部冲击以及实现京津冀地区协同与高质量发展国家战略的重要支撑。

燃煤机组烟气挥发性有机物排放特征

为了解不同容量燃煤机组烟气挥发性有机物(VOCs)的排放特性和不同尾部空气污染物控制设备(APCDs)对VOCs的控制作用,在福建省国投云顶湄洲湾电力公司400 MW亚临界对冲燃烧机组和1 000 MW超超临界切圆燃烧机组进行在线法和离线法采样测试,获取烟气中甲烷、非甲烷总烃和其他VOCs的全流程浓度。结果表明,1 000 MW机组SCR前的非甲烷总烃质量浓度(24.66 mg/m^(3))低于400 MW机组(33.36 mg/m^(3))。由于1 000 MW机组负荷和炉膛温度高,且煤在切圆燃烧炉内比对冲燃烧停留时间长,故煤燃烧更彻底。两机组SCR系统均能脱除超过70%的非甲烷总烃,400 MW和1 000 MW机组的SCR脱除效果分别为88.43%和74.32%。而在静电除尘过程(ESP)中,高压静电场可能会导致飞灰释放部分VOCs,增加烟气VOCs浓度。经所有APCDs后,400 MW机组和1 000 MW机组的VOCs排放质量浓度分别为8.40和8.47 mg/m^(3),整体脱除率为73.98%和63.02%,几乎未检出甲烷。离线测试结果:印尼煤燃烧后VOCs主要为正己烷、苯系物和苯甲醛。各固体样品(如煤、灰、石膏)有机物浓度分析显示,VOCs种类与机组大小无明显关联。这些发现有助于深入理解燃煤电厂对空气质量影响及优化污染控制设备设计。燃煤电厂实际运营中需依具体情况优化污染控制设备,以达到最大脱除效果,也需考虑机组大小和运行效率,有效控制VOCs排放。

非均质黏土地基单桩基础水平极限承载力研究

为减少海上风机长期受到风浪流等水平荷载的影响,利用ABAQUS软件建立非均质黏土单桩基础极限承载力有限元模型,利用温度作为虚拟变量以反映非均质黏性土抗剪强度随深度变化的关系,采用生死单元法进行地应力平衡,并比较有限元得到的水平荷载下单桩基础承载力变化结果与离心机试验结果,以验证其准确性。结合刚性桩与刚柔性桩水平极限荷载下土体失效模式,分析不同长径比、土体弹性模量系数、桩土摩擦因数等参数对单桩基础水平极限承载力影响。结果表明:桩体预埋深度增加后,桩体从刚性桩向刚柔性桩转变,土体破坏模式从楔形、旋转破坏转变为楔形、满流和旋转破坏。土体弹性模量系数对单桩基础水平极限承载力影响较小,长径比和桩土摩擦系数对单桩基础水平极限承载力有较大影响。

Versatile HAR model for realized volatility: A least square model averaging perspective

A rapidly growing body of literature has documented improvements in forecasting financial return volatility measurement using various heterogeneous autoregression(HAR)type models.Most HAR-type models use a fixed lag index of(1,5,22)to mirror the daily,weekly,and monthly components of the volatility process,but they ignore model specification uncertainty.In this paper,we propose applying the least squares model averaging approach to HAR-type models with signed realized semivariance to account for model uncertainty and to allow for a more flexible lag structure.We denote this approach as MARS and prove that the MARS estimator is asymptotically optimal in the sense of achieving the lowest possible mean squared forecast error.Selected by the data-driven model averaging method,the lag combination in the MARS method changes with various data series and different forecast horizons.Employing high frequency data from the NASDAQ 100 index and its 104 constituents,our empirical results demonstrate that acknowledging model uncertainty under the HAR framework and solving with the model averaging method can significantly improve the accuracy of financial return volatility forecasting.

秀珍菇残次菇超声酶解工艺优化及挥发性风味成分分析

为提高秀珍菇副产物的附加值,利用秀珍菇残次菇制备调味基料,筛选适宜的蛋白酶酶解秀珍菇残次菇,基于水解度、模糊数学评定法设计单因素试验和响应面法优化超声波耦合蛋白酶酶解的工艺参数,分析酶解产物的抗氧化性和挥发性风味成分。结果表明,超声酶解最佳工艺条件为料液比1∶30、酶添加量1.5%、pH 7.0、温度47℃、时间72 min、超声功率420 W。在此条件下,秀珍菇水解度、酶解产物得率和综合评分分别为(51.98±3.82)%、(71.83±3.61)%、98.04±3.58;酶解后的总氨基酸含量、抗氧化活性都有显著提高(P<0.05);主要挥发性成分蘑菇醇含量显著增加,月桂烯含量显著减少,且新增了12种挥发性香气成分。该研究结果为秀珍菇残次菇制备调味基料提供了理论和技术支持。

植物乳杆菌R-1对发酵柠檬果汁风味和营养物质的影响

以植物乳杆菌R-1为发酵菌种发酵柠檬果汁,测定发酵过程中柠檬果汁的活菌数、营养物质含量、抗氧化能力和挥发性风味物质含量,探究植物乳杆菌R-1对发酵柠檬果汁风味和营养物质的影响。结果表明:植物乳杆菌R-1在柠檬果汁中具有较好的发酵特性,在发酵36 h后活菌数达到最高值(4×10^(8) CFU/mL),此后趋于稳定;在发酵过程中,植物乳杆菌R-1能降低柠檬果汁中的总糖和有机酸含量,提高总酚含量,在发酵48 h时,总酚含量从最初的47.4 GAE mg/mL显著增加到174.3 GAE mg/mL,同时,发酵柠檬果汁的抗氧化能力(对DPPH和ABTS+自由基的清除能力)显著提高(P<0.05);植物乳杆菌R-1还能改变柠檬果汁中挥发性风味物质的种类和含量,尤其是D-柠檬烯、γ-松油烯等柠檬精油中的特征萜烯类风味物质,其相对含量在发酵24 h时达到最大值,感官评价结果也显示,此时发酵柠檬果汁在香味和口感方面均优于其他发酵时间点的样品。因此,植物乳杆菌R-1能很好地利用柠檬果汁中的营养物质进行生长代谢,并改善柠檬果汁的风味,提高其总酚及抗氧化功能物质的含量。

MoS2/Ti3C2Tx异质复合材料的制备及电化学性能研究

利用水热法合成了MoS2/Ti3C2Tx异质复合材料,采用SEM、XRD、XPS和电化学工作站对所制样品的形貌、结构、成分和电化学性能进行了表征。结果表明,当Ti3C2Tx引入量为30 mg时,所制MoS2/Ti3C2Tx异质复合电极具有最优的电化学性能和较好的循环稳定性,在1 A/g电流密度下的比电容达到262.54 F/g,且经10 000次循环后仍保持82.1%的初始比电容。

基于改进的LMD混合储能容量优化配置

为解决混合储能系统的光伏输出功率波动性较大的问题,提出一种改进的局部均值分解(improved local mean decomposition, ILMD)的功率分配方案。对光伏发电出力进行平滑处理,可得到满足国家要求的光伏并网功率,利用ILMD对混合储能功率进行分解,确定其高频功率和低频功率并分别分配给超级电容和蓄电池,建立具有目标函数的功率优化模型,最大限度地降低整个系统全生命周期的投资成本,使用改进鲸鱼优化算法求解获得符合优化模型要求的容量配置。通过算例分析,对比不同的储能容量配置策略,验证所提策略的可行性。

中国原油期货价格波动时段特征分析及预测

关于原油期货价格波动率的预测研究主要集中在国外市场,中国原油期货合约在一个交易日内被分为3个交易时段,这与国外市场有着很大的不同。交易时间分段可能使中国市场上波动率的结构与国外存在差异。通过异质自回归已实现波动率(HAR-RV)模型框架与半秒钟采样频率的高频期货合约交易数据,对价格波动率的结构特征及预测问题进行研究。研究验证了中国市场上预测的时间尺度由日缩小到交易时段尺度的可行性,发现了中国原油期货价格波动率有时段波动的特征,且时段特征的加入显著提高模型的预测性能。此外,研究还发现,预测时间尺度的缩小促进已实现波动序列平稳性的改善,发展了非平稳时序下HAR-RV模型研究问题,波动率的预测结果可为投资者和管理者对中国原油期货市场设计出更为精准的风险管理工具。

考虑可再生能源波动性的储能电站系统容量配置策略

风力能源、水利能源、太阳能等可再生能源目前在社会上的运用越加重视,可再生能源在存储过程中受时效、季节、天气等的影响,波动性强。论文以黑龙江桦川储能装备实证风电项目为例,通过考虑可再生能源波动性的储能电站系统,容量配置基本原则和设计方案对可再生能源波动性的储能电站系统容量配置原则进行了具体的研究分析。