Extracting angle-domain common-image gathers in VTI media using ansiotropic-Helmholtz P/S wave-mode decomposition

Common-image gathers are extensively used in amplitude versus angle(AVA)and migration velocity analysis(MVA).The current state of methods for anisotropic angle gathers extraction use slant-stack,local Fourier transform or low-rank approximation,which requires much computation.Based on an anisotropic-Helmholtz P/S wave-mode decomposition method,we propose a novel and efficient approach to produce angle-domain common-image gathers(ADCIGs)in the elastic reverse time migration(ERTM)of VTI media.To start with,we derive an anisotropic-Helmholtz decomposition operator from the Christoffel equation in VTI media,and use this operator to derive the decomposed formulations for anisotropic P/S waves.Second,we employ the first-order Taylor expansion to calculate the normalized term of decomposed formulations and obtain the anisotropic-Helmholtz decomposition method,which generates the separated P/S wavefields with correct amplitudes and phases.Third,we develop a novel way that uses the anisotropic-Helmholtz decomposition operator to define the polari-zation angles for anisotropic P/S waves and substitute these angles to decomposing formulations.The polarization angles are then calculated directly from the separated vector P-and S-wavefields and converted to the phase angles.The ADCIGs are thusly produced by applying the phase angles to VTI ERTM.In addition,we develop a concise approximate expression of residual moveout(RMO)for PP-reflections of flat reflectors in VTI media,which avoids the complex transformations between the group angles and the phase angles.The approximate RMO curves show a good agreement with the exact solution and can be used as a tool to assess the migration velocity errors.As demonstrated by two selected examples,our ADCIGs not only produce the correct kinematic responses with regards to different velocity pertubatation,but also generate the reliable amplitude responses versus different angle.The final stacking images of ADCIGs data exhibit the identical imaging effect as that of VTI ERTM.

Local events-based fast RTM surface-offset gathers via dip-guided interpolation

Reverse Time Migration(RTM)Surface Ofset Gathers(SOGs)are demonstrated to deliver more superior residual dip information than ray-based approaches.It appears more powerful in complex geological settings,such as salt areas.Still,the computational cost of constructing RTM SOGs is a big challenge in applying it to 3D feld data.To tackle this challenge,we propose a novel method using dips of local events as a guide for RTM gather interpolation.The residual-dip information of the SOGs is created by connecting local events from depth-domain to time-domain via ray tracing.The proposed method is validated by a synthetic experiment and a feld example.It mitigates the computational cost by an order of magnitude while producing comparable results as fully computed RTM SOGs.

Method for extracting angle-domain common image gathers in Kirchhoff beam migration

Kirchhoff beam migration is a simplified Gaussian beam migration,which omits the dynamic information and can calculate multi-arrival traveltime,so it is a high-precision and fast seismic imaging method.In the imaging process,extracting common image gathers can be used for velocity analysis,improving the accuracy of modeling and imaging quality.Compared with the conventional common image gathers extracting methods,the angle-domain common image gathers extracting method can avoid the artifacts caused by multi-arrival seismic waves.The authors present a new method of extracting common image gathers in angle-domain from Kirchhoff beam migration and verify the method by numerical calculations.

A computational method for wide-azimuth 3D dip-angle gathers using Gaussian beam migration

The dip-angle-domain common-image gather(DDCIG)is a key tool to separate the diffraction and reflection imaging results.Reflectors with different spatial geometries produce different responses in DDCIGs.Compared with Kirchhoff migration,Gaussian beam migration(GBM)is more effective and robust to overcome the multipathing problem.As a ray-based method,it has explicit angle information naturally during the propagation.We have developed a 3D DDCIG computational method using GBM,which obtain both the imaging result and angle-domain gathers with only one pass of calculation.The angle-gather computation is based on geometrical optics,and multiple angle conversions are implemented under the rules of space geometry,which helps to avoid rounding errors and improve accuracy.Additionally,the multi-azimuth joint presentation strategy is proposed to describe the characteristic of omnidirectional dip angles using a finite number of gathers.After using a 2D model to illustrate application advantages of DDCIG,we apply the proposed method to two 3D models to test its feasibility and accuracy.A field data example further demonstrates the adaptability of our method to seismic imaging for a land survey.

Prestack gathers feature enhancement method based on BEMD and CTKEO

The hydrocarbon detection method based on pre-stack gather data has higher accuracy and reliability than those methods based on post-stack data.This kind of method requires that pre-stack gather data have high SNR(Signal Noise Ratio)and obvious AVO(amplitude variation with offset)characteristics.Therefore,it is important to optimize the pre-stack gathers and enhance their AVO(Amplitude variation with offset)effect.This abstract proposes a gather optimization and AVO feature enhanced method for hydrocarbon detection.The gather optimization method based on the improved BEMD(bidimensional empirical mode decomposition).It starts from the original signal directly,and can be optimized as pre-stack gather steadily and quickly.Then,the characters of CTKEO(Corss Teager-Kaiser energy)algorithm which is strong sensitivity to interaction of two signals is fully utilized to enhance AVO features.The method proposed in this abstract provides a good data base for pre-stack inversion from gather optimization to AVO feature enhancement.

Advancing the Modernization Drive of the Global South and Working Together to Build a Community with a Shared Future for Mankind

The 13th Meeting of the China-Africa Think Tanks Forum took place in Dar es Salaam,Tanzania,on March 8,2024.Under the theme of“China-African Practice:Building a Community with a Shared Future”,the forum delved into the major concerns and strategic cooperation between China and Africa in the new era.It aimed to advance the implementation of various initiatives and accomplishments in China-Africa cooperation while also gathering insights for the upcoming session of the Forum on China-Africa Cooperation(FOCAC).

Open to Chinese Democracy

The National People’s Congress meets every year for about a week in March.But there is much more to China’s democracy.SOME 2,977 elected deputies will be attending the second plenary meeting of the 14th National People’s Congress at the Great Hall of the People in Beijing in early March.This,the world’s largest legislative body,is the most striking manifestation of China’s governance system,whole-process people’s democracy.For outsiders,the gathering seems symbolic and ceremonial.However,the deliberation undertaken by the unpaid deputies in the week that they are together is merely the most visible element in a complex consultative system of government.

Matters of Life and Death

In a secluded corner of a café,several young people sit around a small square table laden with an assortment of drinks and desserts.They take turns introducing themselves.The setup is reminiscent of speed dating or a team-building meeting,but the content of discussion is far from either.The unique event is known as Death Café.The purpose of the gathering is to discuss issues related to death.Participants express their thoughts,share experiences and rarely exposed emotions,and offer mutual support amidst a whirlwind of intense feelings.

Enduring Importance

On 5 March,national and global spotlight turned to the Great Hall of the People in Beijing where around 3,000 deputies gathered to open the second session of the 14th National People’s Congress(NPC).Over a span of seven days,the deputies,representing all of China’s ethnic groups,regions and sectors,discussed and decided on a range of issues critical for the country’s development.

A Democracy That Works Western democracies have failed to address people’s livelihood concerns while the Chinese practice has made notable achievements

More than 200 scholars,researchers,former government o!cials and party leaders from over 50 countries gathered in the sprawling building of the Chinese Academy of History in Beijing on 20 March for the third International Forum on Democracy:The Shared Human Values.The forum debated the concept of democracy,its trajectories and prospects,and,more importantly,how it can be made to work and deliver tangible results for di"erent countries.

Prospects delineation and evaluation using the CDP gathers characterization, onshore Nile Delta, Egypt

In the last decade, the seismic AVO analysis have become prominent in the direct hydrocarbons indicator(DHI), aimed at characterizing the fluid content or the lithology of a possible reservoir and reducing theexploration drilling risk. This research discuss the impact of studying the common depth point (CDP)gathers on Near, Mid and Far-offsets, to verify the credibility of the amplitude response in the prospectevaluation, through analyzing a case study of two exploratory wells;one has already penetrated a gasbearing sandstone as a reservoir and the other one is dry-sand, but drilled in two different prospects,using the amplitude versus offset (AVO) analysis, to understand the reservoir configuration and itsrelation to the different amplitude response. The results show, that the missing of the short-offset data isthe reason of the false anomaly encountered in the dry sand, due to some urban surface obstacles duringacquiring the seismic data in the field especially, the study area is located in El Mansoura city, which it isa highly cultivated flat terrain, with multiple channels and many large orchards on the edge of the river,and sugar cane and rice fields. Several lessons have been learned, which how to differentiate between thegas reservoirs and non-reservoirs, by understanding the relation between the Near and Far-offset traces,to reduce the amplitude anomalies to their right justification, where missing of Near-offset data led to apseudo-amplitude anomaly. The results led to a high success of exploration ratio as the positives vastlyoutweigh the negatives.

Guinness Gathers the Weird and Wonderful for 2004

1/If you can pluck a chicken in under 4.4 seconds or swallow 95 worms inhalf a minute,your chance of glory awaits in the ultimate achievers’book. [初译]如果你能在4.4秒之内拔掉一只鸡的毛,或者在半分钟内吞掉95条小虫,那么你将被载入最终获胜者之书中,从而有机会辉煌成名。 [改译]如果你能在4.4秒之内拔光一只鸡的毛。

基于风险评估和参展流程的大型展会疫情风险防控管理实践:以中国国际进口博览会为例

大型展会易发生传染病暴发等公共卫生风险,尤其是新冠疫情暴发后,平衡疫情防控的要求和展会办展体验度是展会行业高质量发展面临的主要难题,相关先进实践经验须进一步总结与推广。通过对5届中国国际进口博览会疫情风险防控成功经验的探索,从展会的参展流程出发,明确各流程中潜在的疫情风险。基于风险评估理论,提出“风险对象分离原则”“疫情防控和展会服务保障组织体系、运行方案和健康促进措施相结合原则”“基于参展参会流程的多点触发监测和实验室检测原则”。同时,基于对不同疫情形势下大型展会疫情防控目标和重点措施的剖析,提出健全组织体系、加强内外联动、风险分级管理、联动开展应急处置等保障模式,相关经验可为今后大型展会疫情风险防控提供参考。

Slow-gathering areas of rivers, lakes, and reservoirs: Definition, estimation, and restoration

Recently,humans have been facing serious water pollution problems that aggravate water resources shortages.By 2025,two-thirds of the world's population is likely to live in countries with moderate or severe water shortages(Azizullah et al.,2011).Rivers,lakes,and reservoirs are important sources of water.Globally,there are approximately 8.5 million rivers(Linke et al.,2019),21.15 million natural lakes,and 1.427 million large reservoirs(Messager et al.,2016).Many of them have been contaminated due to urbanization,industrialization,and agricultural activities.In particular,all rivers,lakes,and reservoirs have their own slow-gathering areas(SGAs)where the input contaminants are easily stopped and deposited due to their non-open morphologies and low flow speeds.

Dataset of Large Gathering Images for Person Identification and Tracking

This paper presents a large gathering dataset of images extracted from publicly filmed videos by 24 cameras installed on the premises of Masjid Al-Nabvi,Madinah,Saudi Arabia.This dataset consists of raw and processed images reflecting a highly challenging and unconstraint environment.The methodology for building the dataset consists of four core phases;that include acquisition of videos,extraction of frames,localization of face regions,and cropping and resizing of detected face regions.The raw images in the dataset consist of a total of 4613 frames obtained fromvideo sequences.The processed images in the dataset consist of the face regions of 250 persons extracted from raw data images to ensure the authenticity of the presented data.The dataset further consists of 8 images corresponding to each of the 250 subjects(persons)for a total of 2000 images.It portrays a highly unconstrained and challenging environment with human faces of varying sizes and pixel quality(resolution).Since the face regions in video sequences are severely degraded due to various unavoidable factors,it can be used as a benchmark to test and evaluate face detection and recognition algorithms for research purposes.We have also gathered and displayed records of the presence of subjects who appear in presented frames;in a temporal context.This can also be used as a temporal benchmark for tracking,finding persons,activity monitoring,and crowd counting in large crowd scenarios.

Deep Learning Based Face Mask Detection in Religious Mass Gathering During COVID-19 Pandemic

Notwithstanding the religious intention of billions of devotees,the religious mass gathering increased major public health concerns since it likely became a huge super spreading event for the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2).Most attendees ignored preventive measures,namely maintaining physical distance,practising hand hygiene,and wearing facemasks.Wearing a face mask in public areas protects people from spreading COVID-19.Artificial intelligence(AI)based on deep learning(DL)and machine learning(ML)could assist in fighting covid-19 in several ways.This study introduces a new deep learning-based Face Mask Detection in Religious Mass Gathering(DLFMD-RMG)technique during the COVID-19 pandemic.The DLFMD-RMG technique focuses mainly on detecting face masks in a religious mass gathering.To accomplish this,the presented DLFMD-RMG technique undergoes two pre-processing levels:Bilateral Filtering(BF)and Contrast Enhancement.For face detection,the DLFMD-RMG technique uses YOLOv5 with a ResNet-50 detector.In addition,the face detection performance can be improved by the seeker optimization algorithm(SOA)for tuning the hyperparameter of the ResNet-50 module,showing the novelty of the work.At last,the faces with and without masks are classified using the Fuzzy Neural Network(FNN)model.The stimulation study of the DLFMD-RMG algorithm is examined on a benchmark dataset.The results highlighted the remarkable performance of the DLFMD-RMG model algorithm in other recent approaches.

Joint Statement of Proposals on Strengthening Silk Road People-to-People Connectivity

We,over 300 representatives from 80 countries,gathered on 18 October 2023 in Beijing for the Thematic Forum on People-to-People Connectivity during the Third Belt and Road Forum for International Cooperation.

The 87th IEC General Meeting

Every year, IEC standardization and conformity assessment experts, member and affiliate countries, and management boards gather at the week-long IEC General Meeting.

Friendly Exchanges Promote Pragmatic Cooperation

The past month saw Chinese leaders and senior diplomats engage in a flurry of diplomatic activities and interchanges.In Xi’an,an ancient city once serving as the capital of 13 dynasties in Chinese history,President Xi Jinping chaired the China-Central Asia Summit,the first in-person gathering attended by the heads of state of six countries,since China established diplomatic ties with them 31 years ago.The milestone summit added considerable impetus to relations between China and Kazakhstan,Kyrgyzstan,Tajikistan,Turkmenistan,and Uzbekistan,and started a new chapter in their cooperation.In Europe,meanwhile,Vice President Han Zheng,senior diplomat Wang Yi,and Foreign Minister Qin Gang met with European leaders in a concerted attempt to find more common ground for pragmatic cooperation between China and European countries–an intention echoed by their European counterparts.