Seasonal influence of freshwater discharge on spatio-temporal variations in primary productivity, sea surface temperature, and euphotic zone depth in the northern Bay of Bengal

Ocean productivity is the foundation of marine food web,which continuously removes atmospheric carbon dioxide and supports life at sea and on land.Spatio-temporal variability of net primary productivity(NPP),sea surface temperature(SST),sea surface salinity(SSS),mixed layer depth(MLD),and euphotic zone depth(EZD) in the northern B ay of Bengal(BoB) during three monsoon seasons were examined in this study based on remote sensing data for the period 2005 to 2020.To compare the NPP distribution between the coastal zones and open BoB,the study area was divided into five zones(Z1-Z5).Results suggest that most productive zones Z2 and Zl are located at the head bay area and are directly influenced by freshwater discharge together with riverine sediment and nutrient loads.Across Z1-Z5,the NPP ranges from 5 315.38 mg/(m^(2)·d) to 346.7 mg/(m^(2)·d)(carbon,since then the same).The highest monthly average NPP of 5 315.38 mg/(m^(2)·d) in February and 5 039.36 mg/(m^(2)·d) in June were observed from Z2,while the lowest monthly average of 346.72 mg/(m^(2)·d) was observed in March from Z4,which is an oceanic zone.EZD values vary from 6-154 m for the study area,and it has an inverse correlation with NPP concentration.EZD is deeper during the summer season and shallower during the wintertime,with a corresponding increase in productivity.Throughout the year,monthly SST shows slight fluctuation for the entire study area,and statistical analysis shows a significant correlation among NPP,and EZD,overall positive between NPP and MLD,whereas no significant correlation among SSS,and SST for the northern BoB.Long-term trends in SST and productivity were significantly po sitive in head bay zones but negatively productive in the open ocean.The findings in this study on the distribution of NPP,SST,SSS,MLD,and EZD and their seasonal variability in five different zones of BoB can be used to further improve the management of marine resources and overall environmental condition in response to climate changes in BoB as they are of utmost relevance to the fisheries for the three bordering countries.

Parameterization for the Depth of the Entrainment Zone above the Convectively Mixed Layer

It has been noted that when the convective Richardson number Ri* is used to characterize the depth of the entrainment zone, various parameterization schemes can be obtained. This situation is often attributed to the invalidity of parcel theory. However, evidence shows that the convective Richardson number Ri* might be an improper characteristic scaling parameter for the entrainment process. An attempt to use an innovative parameter to parameterize the entrainment-zone thickness has been made in this paper. Based on the examination of the data of water-tank experiments and atmospheric measurements, it is found that the total lapse rate of potential temperature across the entrainment zone is proportional to that of the capping inversion layer. Inserting this relationship into the so-called parcel theory, it thus gives a new parameterization scheme for the depth of the entrainment zone. This scheme includes the lapse rate of the capping inversion layer that plays an important role in the entrainment process. Its physical representation is reasonable. The new scheme gives a better ordering of the data measured in both water-tank and atmosphere as compared with the traditional method using Ri*. These indicate that the parcel theory can describe the entrainment process suitably and that the new parameter is better than Ri*.

Formation Depth of Coesite-Bearing Eclogite,Dabie UHPM Zone,China

The plastic deformation of garnet in coesite bearing eclogite, quartz eclogite and garnet amphibolite of the UHPM complex in Yingshan County in the Dabie Mountains has been studied. The stress generated by the strong tectonic movement was an important component of the total pressure that resulted in the formation of the eclogite in the Dabie UHPM zone. The three dimensional tectonic principal stresses and additional tectonic stress induced hydrostatic pressure [ p s=( σ 1+ σ 2+ σ 3)/3] are reconstructed according to the differential stress and the strain ratio ( α ) of the garnet in the minor coesite bearing eclogite of the Yingshan County. Then the gravity induced hydrostatic pressure ( p g) is calculated following the equation p minus p s, where p is estimated to be 2.8 GPa based on the quartz coesite geobarmeter. Therefore, the thickness of the rock column overlying the coesite bearing eclogite in the Ying shan County is determined ≥32 km. This estimation, significantly different from ≥100 km, the previous one obtained solely based on the weight/specific weight ratio (W/SW), offers a proper explanation for the puzzle that no tracer of the addition of mantle derived material has been found in the Dabie UHPM zone during the process of UHPM, although a number of researchers claim that this process took place at the depth of the mantle (≥100 km). It is concluded that attention should be paid to the additional tectonic stress induced hydrostatic pressure in the study of UHPM zones.

跨界一体化导向下的横琴粤澳深度合作区规划与治理创新

以《横琴粤澳深度合作区建设总体方案》的发展目标为导向,结合横琴粤澳深度合作区总体城市设计实践,搭建“空间研判—挑战剖析—规划响应—治理创新”的跨界合作区一体化规划编制框架。通过剖析横琴粤澳深度合作区空间发展情况与琴澳融合瓶颈,从空间布局、产业功能、综合交通、民生服务一体化方面提出规划响应路径,弥补琴澳一体化空间规划的研究空白,在此基础上进一步探索跨界治理机制创新,以规划编制实现功能和形态的空间一体化,通过治理创新增强琴澳协同、破除边界的发展阻力,最终实现一个共建共享的琴澳都会区。

基于充电导体模型的水力压裂电磁响应特征分析

随着中国非常规、超低渗油气资源的大力开发,压裂监测技术迎来重大发展机遇。电磁法在地球物理探测方面具有成本低、时效性强、探测深度大等优点,但面对大深度压裂环境,电磁压裂监测技术的可行性亟须论证。基于充电导体和电偶极源扩散电磁场理论,首先构建了不同深度和不同长度下的裂缝压裂模型,分析了各模型的地面总场及异常场的电磁响应特征。分析结果表明:利用井地电磁法进行压裂监测时,观测总场对裂缝长度增加引起的电磁响应不敏感,异常场存在低值带;深度为4000 m时,电磁异常小于1%,深度越大异常场衰减越严重,且相邻测点间异常场的绝对值与深度呈负相关,电磁法压裂监测技术难以兼顾探测精度与探测深度。然后,通过建立压裂监测物理模型,分析实测数据电磁异常曲线特征,验证了理论计算的正确性。最后,结合前人理论成果和实践经验,提出了一种井中激发—地面接收的测网式电磁法压裂监测观测系统,对测区范围与测点间距进行合理约束,系统具有野外施工简捷、监测深度大等优势,为电磁法压裂监测提供了新的发展方向。

Predicting excavation damage zone depths in brittle rocks

During the construction of an underground excavation, damage occurs in the surrounding rock mass due in large part to stress changes. While the predicted damage extent impacts profile selection and support design, the depth of damage is a critical aspect for the design of permeability sensitive excavations, such as a deep geological repository(DGR) for nuclear waste. Review of literature regarding the depth of excavation damage zones(EDZs) indicates three zones are common and typically related to stress induced damage. Based on past developments related to brittle damage prediction using continuum modelling, the depth of the EDZs has been examined numerically. One method to capture stress induced damage in conventional engineering software is the damage initiation and spalling limit(DISL) approach. The variability of depths predicted using the DISL approach has been evaluated and guidelines are suggested for determining the depth of the EDZs around circular excavations in brittle rock masses. Of the inputs evaluated, it was found that the tensile strength produces the greatest variation in the depth of the EDZs. The results were evaluated statistically to determine the best fit relation between the model inputs and the depth of the EDZs. The best correlation and least variation were found for the outer EDZ and the highly damaged zone(HDZ) showed the greatest variation. Predictive equations for different EDZs have been suggested and the maximum numerical EDZ depths, represented by the 68% prediction interval, agreed well with the empirical evidence. This suggests that the numerical limits can be used for preliminary depth prediction of the EDZs in brittle rock for circular excavations.

超声振动切削对残余应力影响的数值分析

利用AdvantEdge FEM软件对YG6X刀具加工Ti6Al4V合金进行一维和二维超声振动切削仿真,分析超声振动参数对残余应力的影响。模拟仿真表明:一维X向振动时,振动频率和振动幅度对残余应力影响不明显,最大压应力和压应力区深度增大不明显;一维Y向振动时,振动频率越小,残余压应力和压应力区深度越大,振动幅度越大,残余压应力越大,压应力区深度越大;二维振动通过极差分析确定A_(1)B_(1)C_(3)为最佳组合,振动参数对残余应力的影响由大到小依次为A_(y)>(F_(x),F_(y))>A_(x)。结果证明,超声振动切削可以增大工件表层残余应力,改善工件的耐磨性和疲劳强度。

论横琴粤澳深度合作区规则衔接的示范法路径:以合同法为例

从粤港澳大湾区到横琴粤澳深度合作区,在“一国两制”原则下构建统一营商环境的过程中,民商事法律制度及规则的衔接已经成为区域经济一体化发展的现实需求和必然趋势。在践行法律衔接的过程中,除了灵活使用冲突法规则、加强跨境司法合作等方式外,通过起草示范法来推进不同法域间民商事规则的趋同对国家区域法治的发展具有长远的意义。本文以合同法领域为例,通过梳理、比较及归纳内地与澳门特别行政区法律制度中的“同类项”,探索通过示范法路径实现琴澳民商事规则衔接的可能性。

某矿山老采空区地表建设适宜性评价

针对地下矿山老采空区地表建设工程适宜性评价难题,采用工程地质勘探、建筑荷载影响深度判别法、经验公式等手段,综合评价了某矿山老采空区地表建设适宜性。分析结果表明:密实度不够的塌陷回填区不宜作为建设用地,其他老采空区的残留变形基本不影响上方新增建筑物的安全,应重点考虑建筑物自身荷载对老采空区的影响;分别计算建筑物影响深度以及老空区自身的垮落带高度,当建筑荷载引起的地下附加应力等于相应位置处自重应力的20%时,该深度与老空区扣除垮落带高度后的采深比值大小可作为建设用地适应性评价标准,当采深与附加应力影响深度大于2时,为适宜性好;介于1~2时,为基本适宜区;小于1时,为适宜性差区。研究成果为类似老空区地表建设评价提供参考。

基于支护阻力对巷道围岩塑性区深度作用的柔性锚索支护技术研究

为明确支护阻力对巷道围岩塑性区深度的影响,采用卡斯特纳公式和FLAC3D软件分析了支护阻力与巷道围岩塑性区深度之间的关系,分析结果表明:现有技术水平条件下提供的支护阻力不能显著减少巷道围岩塑性区深度,难以有效避免巷道围岩发生塑性破坏,即使支护阻力高达2.50 MPa,巷道顶板围岩塑性区深度也未显著减少。因此,提出采用具有足够承载能力、锚固深度和延伸率的支护材料进行柔性支护,将塑性区内的破坏岩石锚固到塑性区外的稳定岩层是维护巷道围岩稳定的一种有效途径。在信湖煤矿五中车场回风道采用大变形柔性锚索进行补强支护,取得了较好的控制效果,减少了巷道断面的收缩量,保障了巷道的长期使用。

穿越溶洞桥梁桩基嵌岩深度计算方法研究

为准确计算岩溶区桥梁桩基嵌岩深度,依托莆炎高速公路岩溶区桥梁桩基工程,分别考虑桩基竖向极限承载力、桩身稳定性和桥梁全寿命周期内溶洞溶蚀量,提出3种穿越溶洞桥梁桩基嵌岩深度计算方法,并验证3种方法的可靠性。选取34根代表性桩基对比嵌岩深度设计值与所提方法计算值,并选取1根试桩对比规范值与所提方法计算值。结果表明:34根代表性桩基中,1根桩基的嵌岩深度设计值小于考虑全寿命周期内溶洞溶蚀量的嵌岩深度计算值,占比2.9%;10根桩基的嵌岩深度设计值同时满足竖向极限承载力、桩身稳定性和桥梁全寿命周期内溶洞溶蚀量要求,且安全储备合理,占比29.5%;23根桩基存在安全储备较高问题,占比67.6%,其中14.7%的桩基嵌岩深度设计安全储备高达5倍。各规范关于桩基嵌岩深度的取值差异较大,为确保桥梁桩基承载安全,同时降低施工难度和成本,建议设计穿越溶洞桥梁桩基的合理嵌岩深度时,充分考虑桥梁全寿命周期内溶洞溶蚀量。

干湿循环下煤矸石混凝土氯离子分布规律研究

为研究在干湿循环下煤矸石混凝土中氯离子的分布规律,利用质量分数为3.5%的NaCl溶液对煤矸石混凝土进行干湿循环试验,探究了煤矸石替代率(0、25%、50%)、连续干湿循环和非连续干湿循环、干湿比(23∶1、22∶2、20∶4)对混凝土中氯离子浓度与对流区深度等的影响。结果表明,随着混凝土深度增加,氯离子浓度先在距表面0~4 mm上升,随后在4~15 mm急剧下降,之后趋于平稳。随着煤矸石替代率的增加,氯离子浓度整体呈上升趋势,对流区深度随之减小,替代率50%的混凝土对流区深度最小,约为2 mm。煤矸石混凝土的侵蚀深度大于未掺组。干湿比的增大和非连续干湿循环均会导致氯离子峰值浓度和氯离子浓度减小,干湿比为23∶1时,对应的氯离子峰值浓度最大。对流区深度与干湿比的变化无关。

全光纤微震监测技术在底板突水监测中的应用研究

目前国内的光纤微震监测系统多是基于光学光栅传感技术,而光纤光栅波长解调限制了系统检测频率与灵敏度,且长时间、连续不间断的微震监测成功案例较少。针对上述问题,提出了一种新型全光纤微震监测系统。以潘二煤矿11023工作面回采过程中底板突水监测为工程背景,使用全光纤微震监测系统与ESG微震监测系统进行对比,得出全光纤微震监测系统具有以下优势:记录的波形频谱特征更清晰,表现出高信噪比优势;对扰动深度的监测范围更大,远距离监测效果更好;震源定位结果分布更加合理,更符合工作面实际开采情况。在监测工作面回采全周期内,分析了11023工作面断层异常区底板破坏与微震活动性关系:在断层和煤层变薄异常区附近,微震事件的数量增多、强度增大;工作面初采期间应力集中释放,受采动影响,底板破坏较深;相对大能量事件主要分布在断层异常区的底板,底板破坏深度约为27 m,微震事件在3煤底板60 m以下没有成线或成面聚集的情况,说明裂隙并未扩展,未形成导水通道,工作面安全回采。

数字经济赋能横琴粤澳深度合作区高质量发展的机制与路径研究

数字经济是经济增长的新动能,是推动经济高质量发展的重要动力。横琴粤澳深度合作区在发展数字经济方面具有区位、制度、产业、国际合作等优势,也存在高标准统筹规划不完善、部门协调和行政审批障碍多、数据要素市场不健全、数字金融风险频发、核心技术和数字人才不足、工业互联网发展水平不高等挑战。数字经济通过数字生产力,夯实发展动力与经济基础;通过数字分配力,促进成果共享与共同富裕;通过数字流通力,推动要素流通与创新格局;通过数字消费力,实现数实融合与供需匹配;通过数字整合力,优化治理效能与生活方式,进而影响合作区的高质量发展。面对数字经济的机遇与挑战,合作区应发挥五大合力优势,优化顶层设计、加强数据安全治理、防范新型金融风险、突破技术与人才短板。

基于机器学习的房地产市场发展趋势分析——以横琴粤澳深度合作区为例

利用横琴粤澳深度合作区的房地产价格数据,研究对比分析多元线性回归、随机森林、BP神经网络和CATBOOST四种机器学习算法,并在多种特征选择算法的基础上提炼出关键特征,构建出市场发展趋势分析模型。经交叉验证测试发现,CATBOOST算法有着最低的剩余标准差(RMSE),是准确度相对较高的算法,同时研究表明房地产市场发展趋势受区域和地段等位置特征的影响最大。本研究为深入分析区域房地产市场发展趋势提供了新的路径,希望为更为理性的购房决策提供参考。

断裂构造中电阻率与声波波速特征分析及其在探测过程中的联合运用

查明断裂构造的具体位置对于工程场址的选择和稳定性评价具有重要意义。高密度电阻率法和声波测井是广泛运用于探测断裂构造的地球物理方法。高密度电阻率法具有对低阻体敏感且探测范围较大的特点,但高密度电阻率法的分辨率有限,难以准确圈定地质体的边界位置;声波测井具有准确识别地层的特点,但其横向探测范围非常有限。为了克服上述问题,结合2种方法在断裂构造探测中各自的优势以提高圈定地质体的精度,文章首先通过物性试验证明岩石破裂前后电阻率与声波波速变化的相关性,随后用一实例分析断裂构造的电阻率与声波波速特征以及两者在探测过程中的联合运用,最后借助声波测井数据对高密度电阻率法反演结果进行深度校正,得到断裂构造在地下空间的三维分布位置。结果表明:岩石破裂后的电阻率与声波波速较未破裂前均偏低;断裂构造的破碎带在高密度电阻率法反演剖面上以低阻异常区域存在,在声波波速曲线上破碎带区域的波速值会有明显的骤降,2种方法的组合探测模式可为断裂构造具体位置的圈定提供更好的指导。钻探结果验证了借助声波测井数据校正后的高密度电阻率法反演结果比未校正之前更加符合实际地质情况。

横琴粤澳深度合作区与澳门地区跨境金融发展的现状、困境与对策

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