Extraction of Acoustic Normal Mode Depth Functions Using Range-Difference Method with Vertical Linear Array Data

Data-derived normal mode extraction is an effective method for extracting normal mode depth functions in the absence of marine environmental data.However,when the corresponding singular vectors become nonunique when two or more singular values obtained from the cross-spectral density matrix diagonalization are nearly equal,this results in unsatisfactory extraction outcomes for the normal mode depth functions.To address this issue,we introduced in this paper a range-difference singular value decomposition method for the extraction of normal mode depth functions.We performed the mode extraction by conducting singular value decomposition on the individual frequency components of the signal's cross-spectral density matrix.This was achieved by using pressure and its range-difference matrices constructed from vertical line array data.The proposed method was validated using simulated data.In addition,modes were successfully extracted from ambient noise.

Accelerating f inite difference wavef ield-continuation depth migration by GPU

The most popular hardware used for parallel depth migration is the PC-Cluster but its application is limited due to large space occupation and high power consumption. In this paper, we introduce a new hardware architecture, based on which the finite difference （FD） wavefield-continuation depth migration can be conducted using the Graphics Processing Unit （GPU） as a CPU coprocessor. We demonstrate the program module and three key optimization steps for implementing FD depth migration： memory, thread structure, and instruction optimizations and consider evaluation methods for the amount of optimization. 2D and 3D models are used to test depth migration on the GPU. The tested results show that the depth migration computational efficiency greatly increased using the general-purpose GPU, increasing by at least 25 times compared to the AMD 2.5 GHz CPU.

Depth perception differences between hemispheres,genders,and eye dominance A study on evoked potential

BACKGROUND： Certain neural functions, such as peripheral reflexes, differ between genders, while higher brain functions, such as language, are asymmetrically distributed between the two hemispheres. The question remains as to whether depth perception differs between hemispheric laterality and genders, and whether it is affected by eye dominance. OBJECTIVE： To determine whether depth perception is influenced by factors such as gender, eye dominance, and hemispheric lateralization by recording evoked potential associated with depth perception. DESIGN, TIME AND SETTING： A contrast observation based on neuroelectrophysiology was performed at the Department of Biophysics of Ege University Medical School between June 2006 and April 2007. PARTICIPANTS： A total of 34 subjects, 19 females and 15 males, were included in the study with a mean age of （31.0 ± 6.9） years. All subjects were free of neurological or psychological disorders, or problems such as strabismus or vision correction. METHODS： Random-dot stereograms were used to elicit brain activity. A specially designed signal acquisition system employing two computers was used to record evoked potentials from both hemispheres via two pairs of scalp electrodes placed over the occipitotemporal areas of both hemispheres at symmetrical locations. MAIN OUTCOME MEASURES： Negative potential with a mean latency of （211.21 ±25.55） ms and a mean amplitude of （6.05 ± 1.53） pV was recorded from both occipitotemporal areas in 30 out of 34 participants. This was termed ＂Nd＂ and represented the evoked potential associated with depth perception. RESULTS： There were no significant differences in Nd amplitude or latency between the two hemispheres, the two eyes, or genders （P 〉 0.05）. CONCLUSION： The evoked potential associated with depth perception was not influenced by gender, hemisphere, or eye dominance.

Determination Method of Focal Depth of Local Earthquake Using the Travel-time Difference between Pn and sPn

In this paper,we derived the relationships between the travel time difference of sPn and Pn and the local earthquake focal depth.In these equations,the travel time difference of sPn and Pn is not related to the epicentral distance,but depends only on the regional crustal mode and the focal depth.According to the equations,we provided a simple and accurate method to determine local earthquake focal depth by using the travel time difference between phase sPn and Pn.This method has been used to determine the focal depths of two earthquake of MS6.1 and MS5.6 which occurred at the junction of Panzhihua and Huili,Sichuan on August 30 and 31,2008.The results were compared to those from other sources such as the China Earthquake Networks Center,and the comparison shows that the results are accurate and reliable.

生物炭施加对毛竹林不同深度土壤养分含量、重金属及微生物生物量的影响

生物炭作为一种土壤改良剂,不仅在减缓温室气体排放和应对气候变化方面发挥着重要作用,而且对改善农田生态系统质量也具有积极影响。本研究以毛竹Phyllostachys edulis林为研究对象,探讨不同生物炭施加量(0、5和10 t·hm^(-2))对表层(0~20 cm)和深层(20~40 cm)土壤理化性质、重金属含量和微生物生物量的影响。研究发现:与对照(0 t·hm^(-2))相比,生物炭施加显著提升了表层和深层土壤的pH值(1.3%~12.2%)、有机碳(8.8%~51.5%)、总磷含量(14.2%~31.5%)和深层土壤的含水率(4.2%~13.3%),并且这种积极效应随着生物炭施加水平增加而增加(P<0.05)。高生物炭施加显著降低了表层土和深层土壤的有效态铅(28.6%、51.1%)、镉(11.1%、7.2%)和铜(10.9%、12.2%)的含量,但显著增加了土壤微生物量碳和氮及纤维素酶活性(P<0.05)。在生物炭施加处理下,表层土的pH值、总磷、有效态铅含量、微生物量碳和氮显著高于深层土,而总氮、有效氮、含水率和有效态镉含量则呈现相反的趋势(P<0.05)。相关性分析揭示了土壤微生物生物量与土壤pH、总磷和有效镉含量存在显著的相关性(P<0.05)。研究结果表明,生物炭施加不仅可以缓解土壤酸化,减缓镉污染,还能提高微生物生物量,从而提升土壤质量。因此,从土壤质量角度出发,生物炭施加可以被视作一种有效的竹林土壤改良措施,对于推动毛竹林的可持续发展具有重要的实践价值。

Finite-difference calculation of traveltimes based on rectangular grid

To the most of velocity fields, the traveltimes of the first break that seismic waves propagate along rays can be computed on a 2-D or 3-D numerical grid by finite-difference extrapolation. Under ensuring accuracy, to improve calculating efficiency and adaptability, the calculation method of first-arrival traveltime of finite-difference is de- rived based on any rectangular grid and a local plane wavefront approximation. In addition, head waves and scat- tering waves are properly treated and shadow and caustic zones cannot be encountered, which appear in traditional ray-tracing. The testes of two simple models and the complex Marmousi model show that the method has higher accuracy and adaptability to complex structure with strong vertical and lateral velocity variation, and Kirchhoff prestack depth migration based on this method can basically achieve the position imaging effects of wave equation prestack depth migration in major structures and targets. Because of not taking account of the later arrivals energy, the effect of its amplitude preservation is worse than that by wave equation method, but its computing efficiency is higher than that by total Green′s function method and wave equation method.

基于声发射多参数耦合的木材裂缝检测方法

为及时了解木材的损伤情况,需对木材进行损伤评价,而木材裂缝深度是评价木材损伤的重要指标之一,其量测方法是一大难点,亟待解决。基于声发射参数(峰值、频率重心、能量)在杉木裂缝中的衰减规律,应用加权平均法对声发射参数进行归一化处理,提出了基于声发射多参数耦合的裂缝深度检测方法。结果表明:声发射峰值、频率重心、能量在木材存在裂缝与无裂缝的交界面会发生突变,且所提的基于声发射多参数耦合的综合指标值在交界面大于设定阈值,能有效检测木材的裂缝深度。

不同麻醉深度对老年腹部手术患者术后认知功能的影响

目的:探讨不同麻醉深度对老年腹部手术患者术后认知功能的影响。方法:选取78例老年腹部手术患者作为研究对象,依据脑电双频指数(BIS)不同将患者分为对照组(浅麻醉,BIS≥45)和研究组(深麻醉,30<BIS<45),每组各39例。比较两组患者手术相关指标、血流动力学指标、白细胞介素6(IL-6)水平、中枢神经特异蛋白(S-100β)水平、简易精神状态检查表(MMSE)评分及术后认知功能障碍(POCD)发生率。结果:两组患者输液量、麻醉时间、术中出血量比较,差异均无统计学意义(P>0.05);研究组苏醒时间、拔管时间长于对照组(P<0.05);两组患者术后1、3 d,血清IL-6、S-100β水平先升高后降低(P<0.05),且研究组术后各时间均低于对照组(P<0.05);在麻醉后研究组T1、T2时间点的平均动脉压均高于对照组,T1、T2心率均低于对照组(P<0.05);术后1、3 d,研究组MMSE评分高于对照组;术后1、3、7 d,研究组POCD发生率均低于对照组(P<0.05)。结论:深度麻醉(BIS:30~45)可降低老年腹部手术患者发生POCD的几率及血清IL-6和S-100β水平,在减轻中枢神经系统损伤方面具有积极作用。

仪表着陆系统调制度差分析及应用验证

仪表着陆系统(Instrument Landing System,ILS)对飞机进近着陆安全起到基础性保障作用。研究航迹偏离刻度(DOT)、调制度差(Difference in Depth of Modulation,DDM)与航迹偏离角三者间的关系可以进一步量化DOT,显示DDM与真实航迹偏离角的数量关联,为飞行事故调查提供量化依据。基于仪表着陆系统原理建立了ILS数字化波形仿真模型;并通过飞行数据进行回归分析,对国内某机场04R跑道的ILS信号进行实例分析,求解了飞机进近阶段DOT、DDM与航迹偏离角间的定量关系;同时讨论了影响飞机进近安全的次级下滑道现象,为飞行数据分析提供了可行的量化计算方法。

Dynamic mechanical characteristics of deep Jinping marble in complex stress environments

To reveal the dynamic mechanical characteristics of deep rocks,a series of impact tests under triaxial static stress states corresponding to depths of 300-2400 m were conducted.The results showed that both the strain rates and the stress environments in depth significantly affect the mechanical characteristics of rocks.The sensitivity of strain rate to the dynamic strength and deformation modulus shows a negative correlation with depth,indicating that producing penetrative cracks in deep environments is more difficult when damage occurs.The dynamic strength shows a tendency to decrease and then increase slightly,but decreases sharply finally.Transmissivity demonstrates a similar trend as that of strength,whereas reflectivity indicates the opposite trend.Furthermore,two critical depths with high dynamically induced hazard possibilities based on the China Jinping Underground Laboratory(CJPL)were proposed for deep engineering.The first critical depth is 600-900 m,beyond which the sensitivity of rock dynamic characteristics to the strain rate and restraint of circumferential stress decrease,causing instability of surrounding rocks under axial stress condition.The second one lies at 1500-1800 m,where the wave impedance and dynamic strength of deep surrounding rocks drop sharply,and the dissipation energy presents a negative value.It suggests that the dynamic instability of deep surrounding rocks can be divided into dynamic load dominant and dynamic load induced types,depending on the second critical depth.

鄱阳湖流域地下水埋深时空分布特征

近年来干旱事件频发,在许多地区日益缺水的背景下,地下水的合理开发利用与妥善管理成为迫切需求。基于2018-2022年鄱阳湖流域逐日地下水位,采用聚类分析、克里金空间插值、重心迁移等方法对流域不同时间尺度下地下水埋深时空分布特征进行分析。结果表明:鄱阳湖流域地下水埋深多年变化呈现平稳型、“V”型和“N”型三种模式,受2019年、2022年干旱影响,流域中部地区出现短时间内地下水埋深迅速增大的情况。鄱阳湖流域地下水埋藏空间分布特征为中心深四周浅,地下水埋深由内向外逐渐减小,汛期地下水埋藏明显较非汛期浅,且地下水埋深中心向东北方向迁移。研究成果可为保障鄱阳湖流域水安全及可持续发展提供重要科学参考。

青藏高原多尔索洞错水深反演与水量变化估算

利用由实测水深空间插值获得的水下地形数据估算湖泊水量及其变化往往存在较大误差。以Landsat系列影像数据及多尔索洞错12 m以下实测水深数据为基础,建立多波段组合模型进行水深模拟,结合多时相Landsat影像获取的多尔索洞错边界数据获取水深变化,估算1996~2016年多尔索洞错水量变化。实验结果表明:多因子反演模型的相关系数(R^(2))均在0.90以上,平均绝对误差低至0.48 m,相比空间插值方法能更精确地模拟多尔索洞错水深在12 m以下区域的水深分布情况;近20 a来多尔索洞错不断扩张,水位升高约0.40 m/a,水量增加约0.18 km^(3)/a。

基于显著特征分类的立体图像重定向方法

现有立体图像重定向方法对不同特征图像均采用相同的策略进行重定向操作,导致一些立体重定向图像出现信息丢失、形变扭曲或深度改变的情况。影响立体图像重定向结果质量的因素主要包括显著区域形状和可视深度的改变等。为了解决这些问题,提出一种基于图像显著特征分类的立体图像重定向方法,将图像分为无显著及有显著2类图像,结合立体智能剪裁方法及立体非均匀映射方法对不同特征图像采用不同的重定向策略以减少信息丢失及几何失真。通过利用显著区域与非显著区域的深度信息差异可以更好地保持显著图像的深度感。实验结果表明,提出方法在主观对比及客观指标评价中均取得了优于其他算法的效果。

基于卡尔曼滤波的仪表着陆机载设备解算处理

仪表着陆系统在测量中用到了多种滤波来提高精度,例如数字滤波器等,可系统在测量中仍然会受飞行姿态、环境、测量不确定性等因素的影响,在测量值与真值之间出现一定偏差,亦或测量值出现部分毛刺跳变。考虑到滤波算法都是需要一定的运算数据和硬件资源,算法越复杂占用资源越多。从实际工程应用出发,选用具有计算效率高、稳定性强和存贮量要求不高等特点的卡尔曼滤波算法,将其应用于仪表着陆机载设备中,来提高测量精度。

基于视觉理论的动态点云剔除算法

针对动态场景下构建的点云地图中包含大量动态目标的错误点云问题,提出一种基于视觉理论将三维点云转换视觉图像的动态点云剔除算法。通过对当前帧和包含动态点云的噪声地图做点云的地面分割和高度分割,将点云的深度信息转换成视觉可用的图像信息,利用视觉理论中的背景差分法对当前帧和噪声地图进行深度图像对比,筛选出初始动态点云并计算动态分数;根据动态分数对初始动态点云进行自适应最近邻搜索以剔除动态目标。实验结果表明,所提算法的动态点云剔除率可达94%以上,整体得分为96.34,能有效剔除场景中的动态目标。

右美托咪定复合不同麻醉深度对老年全髋关节置换术患者认知功能及血流动力学的影响

目的探讨右美托咪定复合不同麻醉深度对老年全髋关节置换术(THA)患者认知功能及血流动力学的影响。方法回顾性分析2021年6月至2023年6月鹰潭市人民医院收治的80例老年THA患者资料,根据脑电双频指数(BIS)将其分为A组(BIS值为40~49,n=26)、B组(BIS值为50~59,n=27)、C组(BIS值为60~69,n=27)。三组不同麻醉深度的患者均行THA治疗,术中采用右美托咪定复合麻醉。比较三组认知功能、血流动力学及安全性。结果三组术前认知功能评分、血流动力学以及不良反应发生率比较,差异无统计学意义(P>0.05)。三组患者术后12 h认知功能评分低于本组术前,术后24、72 h认知功能评分高于术后12 h,B组术后各时点认知功能评分均高于A、C组,差异有统计学意义(P<0.05)。A、C组术后不同时点收缩压和舒张压均低于本组术前,心率均高于本组术前,且A、C组术后不同时点收缩压和舒张压均低于B组,心率高于B组,差异有统计学意义(P<0.05)。结论老年THA患者采用右美托咪定复合BIS值为50~59的麻醉深度效果最好,利于维持血流动力学平稳,改善认知功能,且不会增加不良反应,值得临床广泛应用。

不同剂量甲苯磺酸瑞马唑仑全麻诱导对老年患者镇静深度的影响

目的:探讨不同剂量甲苯磺酸瑞马唑仑全麻诱导对老年患者镇静深度的影响。方法:选取2020年1月—2021年12月广州医科大学附属第一医院收治110例采用甲苯磺酸瑞马唑仑全麻诱导的老年患者,按照随机数表法分成观察组与对照组,各55例。观察组甲苯磺酸瑞马唑仑诱导剂量为0.3 mg/kg,对照组甲苯磺酸瑞马唑仑诱导剂量为0.2 mg/kg。比较两组达到深度麻醉时间、生命体征、不良反应、药物补救情况。结果:观察组达到深度麻醉时间明显短于对照组,差异有统计学意义(P<0.05);两组心率、每搏量指数、平均动脉压(MAP)比较,差异无统计学意义(P>0.05)。两组不良反应总发生率比较,差异无统计学意义(P>0.05)。观察组药物补救发生率低于对照组,差异有统计学意义(P<0.05)。结论:高剂量甲苯磺酸瑞马唑仑全麻诱导应用于老年患者后起效速度更快,不会对患者生命体征造成严重影响,且药物补救概率低。

7号低压加热器汽侧水位异常原因分析及处理

近年来,许多火力发电厂都参与电网的深度调峰,在机组深度调峰期间,7号低压加热器汽侧水位频繁出现高水位报警现象,并联启7号低压加热器危急疏水阀,将造成8号低压加热器换热效率降低、凝汽器汽侧温度升高以及机组真空恶化等不良影响。通过分析高水位报警时的其他关联数据的变化、水位检测装置是否准确及相关管道阀门有无异常等因素,发现高水位报警主要是由于低负荷时凝结水量增加及7、8号低压加热器汽侧压差偏小的问题使凝结水无法及时通过正常疏水管道排至8号低压加热器所造成的,本文采取相应的对策予以处理,保证7号低压加热器汽侧水位在深度调峰期间保持稳定。

基于钻孔土层参数的黄金开采地质特征三维模拟

为了解决黄金开采过程中由于数据不足和参数偏差等不确定因素导致的地质特征分析难度大的问题,提出一种基于钻孔土层参数的黄金开采地质特征三维模拟方法,以改进资源储量估算的准确性。采用钻探设备获取钻孔土层信息,并利用距离反比加权差值法优化钻孔土层参数,建立包含地质参数的数据库。基于这些参数,可以使用Surpac软件来构建具有地下空间的三维模型,生成黄金开采区不同地质特征。实验测试结果显示:该钻孔土层参数能够构建较为理想的黄金开采区地下空间三维模型,同时还能模拟出地下空间黄金开采不同深度的地质特征,划分出研究区域的断裂带以及金矿分布、侵入岩位置,准确估算出金矿储量,误差值在2%以内。所提出的基于钻孔土层参数的黄金开采地质特征三维模拟方法具有较高的可行性和准确性。该研究方法的应用可以提高黄金开采区地质特征分析的准确性和可信度,有助于更好地理解研究区域的地质环境,为黄金开采过程中的决策制定提供准确的地质数据支持。

极近距离煤层群不同层间距下回采巷道支护技术研究

针对高家庄煤矿极近距离煤层群采空区下方4201工作面轨道巷掘进过程中,由于层间距不断变化,导致局部顶板破坏严重、裂隙发育等问题,采用理论计算和现场实测方法研究底板最大破坏深度和层间距变化规律,将顶板层间距大小划分小于2.8 m、2.8~3.8 m和大于3.8 m三个支护分区,分别制定了工字钢架棚+锚杆支护、短锚索网支护和长短锚索网支护3种支护方案。现场应用结果表明,4201轨道巷掘进期间顶板完整性提高,围岩变形量小于100 mm,满足使用要求。