期刊文献+
共找到4,619篇文章
< 1 2 231 >
每页显示 20 50 100
A Generative Adversarial Network with an Attention Spatiotemporal Mechanism for Tropical Cyclone Forecasts
1
作者 Xiaohui LI Xinhai HAN +5 位作者 Jingsong YANG Jiuke WANG Guoqi HAN Jun DING Hui SHEN Jun YAN 《Advances in Atmospheric Sciences》 2025年第1期67-78,共12页
Tropical cyclones(TCs)are complex and powerful weather systems,and accurately forecasting their path,structure,and intensity remains a critical focus and challenge in meteorological research.In this paper,we propose a... Tropical cyclones(TCs)are complex and powerful weather systems,and accurately forecasting their path,structure,and intensity remains a critical focus and challenge in meteorological research.In this paper,we propose an Attention Spatio-Temporal predictive Generative Adversarial Network(AST-GAN)model for predicting the temporal and spatial distribution of TCs.The model forecasts the spatial distribution of TC wind speeds for the next 15 hours at 3-hour intervals,emphasizing the cyclone's center,high wind-speed areas,and its asymmetric structure.To effectively capture spatiotemporal feature transfer at different time steps,we employ a channel attention mechanism for feature selection,enhancing model performance and reducing parameter redundancy.We utilized High-Resolution Weather Research and Forecasting(HWRF)data to train our model,allowing it to assimilate a wide range of TC motion patterns.The model is versatile and can be applied to various complex scenarios,such as multiple TCs moving simultaneously or TCs approaching landfall.Our proposed model demonstrates superior forecasting performance,achieving a root-mean-square error(RMSE)of 0.71 m s^(-1)for overall wind speed and 2.74 m s^(-1)for maximum wind speed when benchmarked against ground truth data from HWRF.Furthermore,the model underwent optimization and independent testing using ERA5reanalysis data,showcasing its stability and scalability.After fine-tuning on the ERA5 dataset,the model achieved an RMSE of 1.33 m s^(-1)for wind speed and 1.75 m s^(-1)for maximum wind speed.The AST-GAN model outperforms other state-of-the-art models in RMSE on both the HWRF and ERA5 datasets,maintaining its superior performance and demonstrating its effectiveness for spatiotemporal prediction of TCs. 展开更多
关键词 tropical cyclones spatiotemporal prediction generative adversarial network attention spatiotemporal mechanism deep learning
下载PDF
A Location Trajectory Privacy Protection Method Based on Generative Adversarial Network and Attention Mechanism
2
作者 Xirui Yang Chen Zhang 《Computers, Materials & Continua》 SCIE EI 2024年第12期3781-3804,共24页
User location trajectory refers to the sequence of geographic location information that records the user’s movement or stay within a period of time and is usually used in mobile crowd sensing networks,in which the us... User location trajectory refers to the sequence of geographic location information that records the user’s movement or stay within a period of time and is usually used in mobile crowd sensing networks,in which the user participates in the sensing task,the process of sensing data collection faces the problem of privacy leakage.To address the privacy leakage issue of trajectory data during uploading,publishing,and sharing when users use location services on mobile smart group sensing terminal devices,this paper proposes a privacy protection method based on generative adversarial networks and attention mechanisms(BiLS-A-GAN).The method designs a generator attention model,GAttention,and a discriminator attention model,DAttention.In the generator,GAttention,combined with a bidirectional long short-term memory network,more effectively senses contextual information and captures dependencies within sequences.The discriminator uses DAttention and the long short-term memory network to distinguish the authenticity of data.Through continuous interaction between these two models,trajectory data with the statistical characteristics of the original data is generated.This non-original trajectory data can effectively reduce the probability of an attacker’s identification,thereby enhancing the privacy protection of user information.Reliability assessment of the Trajectory-User Linking(TUL)task performed on the real-world semantic trajectory dataset Foursquare NYC,compared with traditional privacy-preserving algorithms that focus only on the privacy enhancement of the data,this approach,while achieving a high level of privacy protection,retains more temporal,spatial,and thematic features from the original trajectory data,to not only guarantee the user’s personal privacy,but also retain the reliability of the information itself in the direction of geographic analysis and other directions,and to achieve the win-win purpose of both data utilization and privacy preservation. 展开更多
关键词 Privacy protection trajectory generation generative adversarial networks attention mechanism location trajectory
下载PDF
Quantum generative adversarial networks based on a readout error mitigation method with fault tolerant mechanism
3
作者 赵润盛 马鸿洋 +2 位作者 程涛 王爽 范兴奎 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第4期285-295,共11页
Readout errors caused by measurement noise are a significant source of errors in quantum circuits,which severely affect the output results and are an urgent problem to be solved in noisy-intermediate scale quantum(NIS... Readout errors caused by measurement noise are a significant source of errors in quantum circuits,which severely affect the output results and are an urgent problem to be solved in noisy-intermediate scale quantum(NISQ)computing.In this paper,we use the bit-flip averaging(BFA)method to mitigate frequent readout errors in quantum generative adversarial networks(QGAN)for image generation,which simplifies the response matrix structure by averaging the qubits for each random bit-flip in advance,successfully solving problems with high cost of measurement for traditional error mitigation methods.Our experiments were simulated in Qiskit using the handwritten digit image recognition dataset under the BFA-based method,the Kullback-Leibler(KL)divergence of the generated images converges to 0.04,0.05,and 0.1 for readout error probabilities of p=0.01,p=0.05,and p=0.1,respectively.Additionally,by evaluating the fidelity of the quantum states representing the images,we observe average fidelity values of 0.97,0.96,and 0.95 for the three readout error probabilities,respectively.These results demonstrate the robustness of the model in mitigating readout errors and provide a highly fault tolerant mechanism for image generation models. 展开更多
关键词 readout errors quantum generative adversarial networks bit-flip averaging method fault tolerant mechanisms
下载PDF
HybridGAD: Identification of AI-Generated Radiology Abstracts Based on a Novel Hybrid Model with Attention Mechanism
4
作者 TugbaÇelikten Aytug Onan 《Computers, Materials & Continua》 SCIE EI 2024年第8期3351-3377,共27页
Class Title:Radiological imaging method a comprehensive overview purpose.This GPT paper provides an overview of the different forms of radiological imaging and the potential diagnosis capabilities they offer as well a... Class Title:Radiological imaging method a comprehensive overview purpose.This GPT paper provides an overview of the different forms of radiological imaging and the potential diagnosis capabilities they offer as well as recent advances in the field.Materials and Methods:This paper provides an overview of conventional radiography digital radiography panoramic radiography computed tomography and cone-beam computed tomography.Additionally recent advances in radiological imaging are discussed such as imaging diagnosis and modern computer-aided diagnosis systems.Results:This paper details the differences between the imaging techniques the benefits of each and the current advances in the field to aid in the diagnosis of medical conditions.Conclusion:Radiological imaging is an extremely important tool in modern medicine to assist in medical diagnosis.This work provides an overview of the types of imaging techniques used the recent advances made and their potential applications. 展开更多
关键词 generative artificial intelligence AI-generated text detection attention mechanism hybrid model for text classification
下载PDF
Intrinsic correlation between the generalized phase equilibrium condition and mechanical behaviors in hydrate-bearing sediments
5
作者 Jiazuo Zhou Changfu Wei +2 位作者 Rongtao Yan Yuan Zhou Yi Dong 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第7期2822-2832,共11页
The phase equilibrium and mechanical behaviors of natural gas hydrate-bearing sediment are essential for gas recovery from hydrate reservoirs.In heating closed systems,the temperature-pressure path of hydrate-bearing ... The phase equilibrium and mechanical behaviors of natural gas hydrate-bearing sediment are essential for gas recovery from hydrate reservoirs.In heating closed systems,the temperature-pressure path of hydrate-bearing sediment deviates from that of pure bulk hydrate,reflecting the porous media effect in phase equilibrium.A generalized phase equilibrium equation was established for hydrate-bearing sediments,which indicates that both capillary and osmotic pressures cause the phase equilibrium curve to shift leftward on the temperature-pressure plane.In contrast to bulk hydrate,hydrate-bearing sediment always contains a certain amount of unhydrated water,which keeps phase equilibrium with the hydrate within the hydrate stability field.With changes in temperature and pressure,a portion of pore hydrate and unhydrated water may transform into each other,affecting the shear strength of hydrate-bearing sediment.A shear strength model is proposed to consider not only hydrate saturation but also the change in temperature and pressure of hydrate-bearing sediment.The model is validated by experimental data with various hydrate saturation,temperature and pressure conditions.The deformation induced by partial dissociation was studied through depressurization tests under constant effective stress.The reduction in gas pressure within the hydrate stability field indeed caused sediment deformation.The dissociation-induced deformation can be reasonably estimated as the difference in volume between hydrate-bearing and hydrate-free sediments from the compression curves. 展开更多
关键词 Hydrate-bearing sediment generalized phase equilibrium Unhydrated water Partial dissociation mechanical behavior
下载PDF
Mechanism of generation of large(Ti,Nb,V)(C,N)-type precipitates in H13 + Nb tool steel 被引量:4
6
作者 You Xie Guo-guang Cheng +2 位作者 Lie Chen Yan-dong Zhang Qing-zhong Yan 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2016年第11期1264-1274,共11页
The characteristics and generation mechanism of(Ti,Nb,V)(C,N) precipitates larger than 2 μm in Nb-containing H13 bar steel were studied. The results show that two types of(Ti,Nb,V)(C,N) phases exist—a Ti-V-r... The characteristics and generation mechanism of(Ti,Nb,V)(C,N) precipitates larger than 2 μm in Nb-containing H13 bar steel were studied. The results show that two types of(Ti,Nb,V)(C,N) phases exist—a Ti-V-rich one and an Nb-rich one—in the form of single or complex precipitates. The sizes of the single Ti-V-rich(Ti,Nb,V)(C,N) precipitates are mostly within 5 to 10 μm, whereas the sizes of the single Nb-rich precipitates are mostly 2–5 μm. The complex precipitates are larger and contain an inner Ti-V-rich layer and an outer Nb-rich layer. The compositional distribution of(Ti,Nb,V)(C,N) is concentrated. The average composition of the single Ti-V-rich phase is(Ti_(0.511)V_(0.356)Nb_(0.133))(CxNy), whereas that for the single Nb-rich phase is(Ti_(0.061)V_(0.263)Nb_(0.676))(C_xN_y). The calculation results based on the Scheil–Gulliver model in the Thermo-Calc software combining with the thermal stability experiments show that the large phases precipitate during the solidification process. With the development of solidification, the Ti-V-rich phase precipitates first and becomes homogeneous during the subsequent temperature reduction and heat treatment processes. The Nb-rich phase appears later. 展开更多
关键词 precipitates carbonitrides generating mechanism tool steel niobium
下载PDF
Unsupervised multi-modal image translation based on the squeeze-and-excitation mechanism and feature attention module
7
作者 胡振涛 HU Chonghao +1 位作者 YANG Haoran SHUAI Weiwei 《High Technology Letters》 EI CAS 2024年第1期23-30,共8页
The unsupervised multi-modal image translation is an emerging domain of computer vision whose goal is to transform an image from the source domain into many diverse styles in the target domain.However,the multi-genera... The unsupervised multi-modal image translation is an emerging domain of computer vision whose goal is to transform an image from the source domain into many diverse styles in the target domain.However,the multi-generator mechanism is employed among the advanced approaches available to model different domain mappings,which results in inefficient training of neural networks and pattern collapse,leading to inefficient generation of image diversity.To address this issue,this paper introduces a multi-modal unsupervised image translation framework that uses a generator to perform multi-modal image translation.Specifically,firstly,the domain code is introduced in this paper to explicitly control the different generation tasks.Secondly,this paper brings in the squeeze-and-excitation(SE)mechanism and feature attention(FA)module.Finally,the model integrates multiple optimization objectives to ensure efficient multi-modal translation.This paper performs qualitative and quantitative experiments on multiple non-paired benchmark image translation datasets while demonstrating the benefits of the proposed method over existing technologies.Overall,experimental results have shown that the proposed method is versatile and scalable. 展开更多
关键词 multi-modal image translation generative adversarial network(GAN) squeezeand-excitation(SE)mechanism feature attention(FA)module
下载PDF
Novel Mobility Formula for Parallel Mechanisms Expressed with Mobility of General Link Group 被引量:14
8
作者 ZHANG Yitong LU Wenjuan +3 位作者 MU Dejun YANG Yandong ZHANG Lijie ZENG Daxing 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2013年第6期1082-1090,共9页
The determination of virtual constraints is always one of the key and difficult problems in traditional mobility calculation. To make mobility calculation simple, considering avoiding virtual constraints, some new for... The determination of virtual constraints is always one of the key and difficult problems in traditional mobility calculation. To make mobility calculation simple, considering avoiding virtual constraints, some new formulae have been presented, however these formulae can hardly intuitively reflect general link group's restrictions on output member and its influences on independence of output parameters, which is premise to the judgment of the properties of mobility. Towards the problem to reveal the intrinsic relationship between the degree of freedom(DOF) of a mechanism, the link group, and the dimension of output parameters, also to avoid determination of virtual constraint, based on the new concepts of the "DOF of general link group" and "node parameters", a new formula in the calculation of the mobility of mechanisms is presented that is expressed with DOFs of the general link groups and rank of motion parameters of base point of the output link. It is named GOM(mobility of groups and output parameter) formula. On the basis of new concepts of"effective parameters" and "invalid parameters", a rule is put forward for solving the DOF of mechanisms with invalid parameters by GOM formula, that is, the base point parameters are the subset of effective parameters of link group. Thereafter, several examples are enumerated and the results coincide with the prototype data, which proves the validity of the proposed formula. Meanwhile, it is obtained that the necessary and sufficient condition for the judgment of output parameters independence is that each of the DOF of the link group is not less than zero. The proposed formula which is simple in calculation provides theoretical basis for the judgment of independence of output parameters and provides references for type synthesis of novel parallel mechanisms with independence requirements of their output parameters. 展开更多
关键词 parallel mechanism degree of freedom general link group output parameters
下载PDF
EXPERIMENTAL INVESTIGATION ON GENERATION MECHANISM OF EXPLOSIVE STRESS WAVES 被引量:2
9
作者 Xu, Guoyuan Gu, Desheng 《中国有色金属学会会刊:英文版》 EI CSCD 1999年第2期229-232,共4页
1INTRODUCTIONExplosivestresswavesarequiteimportantinrockfragmentationproces.Manyscholarshaveinvestigatedtheg... 1INTRODUCTIONExplosivestresswavesarequiteimportantinrockfragmentationproces.Manyscholarshaveinvestigatedthegenerationandpropa... 展开更多
关键词 generATION mechanism of EXPLOSIVE STRESS wavesshock energybubble energy
下载PDF
Generating Electricity from Mechanical Vibrations:Optimization of Linear a Generator 被引量:2
10
作者 MAA KARUNARATHNA KAM DHANURANGA 《Instrumentation》 2021年第2期34-39,共6页
Energy preservation is one of the key components in developing eco-friendly machines.In industry,the majority of machines lose a considerable amount of energy through mechanical vibrations.However,the wasted energy th... Energy preservation is one of the key components in developing eco-friendly machines.In industry,the majority of machines lose a considerable amount of energy through mechanical vibrations.However,the wasted energy through vibration can be utilized as a renewable energy source to compensate for the overall energy loss.The research work presented in this paper discusses the ability to design a linear power generator utilizing Nd Fe-B magnets,which can generate energy through mechanical vibrations.A pilot model was developed and simulated to understand the efficiency and limitation.The results showed that the model could reduce 14% rotor bulk with a marginal impact on the current generation. 展开更多
关键词 mechanical Vibrations Linear generator Sustainable Energy Energy Production
下载PDF
Status of research on biogenic coalbed gas generation mechanisms 被引量:7
11
作者 WANG, Aikuan QIN, Yong +1 位作者 WU, Yanyan WANG, Baowen 《Mining Science and Technology》 EI CAS 2010年第2期271-275,共5页
Biogenic coalbed gas,how it is generated and the geochemical characteristics of the gas are gaining global attention.The ways coalbed gas is generated,the status of research on the generation mechanism and the methods... Biogenic coalbed gas,how it is generated and the geochemical characteristics of the gas are gaining global attention.The ways coalbed gas is generated,the status of research on the generation mechanism and the methods of differentiating between biogenic gasses are discussed.The generation of biogenic coalbed methane is consistent with anaerobic fermentation theory.Commercial biogenic coalbed gas reservoirs are mainly generated by the process of CO2 reduction.The substrates used by the microbes living in the coal include organic compounds,CO2,H2 and acetate.The production ratio and quantity of biogenic coalbed methane depend on the exposed surface area,the solubility and permeability of the coal and the microbial concentration in the coal seam.It is generally believed that biogenic coalbed gas has a value for δ13C1<-5.5%,C1/C1+>0.95.The H isotope ratio is controlled by both the environment and the generation mechanism:typically δD1<-20%.Biogenic methane formed by CO2 reduction has more δD1 than that formed by acetate fermentation. 展开更多
关键词 coalbed gas biogenic coalbed gas secondary biogenic coalbed gas generation mechanism DISCRIMINATION
下载PDF
RELIABILITY-BASED ANALYSIS AND SYNTHESIS OF MECHANICAL ERROR FOR PATH GENERATING LINKAGES 被引量:15
12
作者 Shi Zhongxiu ,Li FengqiangQingdao University 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 1997年第2期130-135,共3页
A reliability-based analysis approach to mechanical error in path generating linkages is pre- sented . The reliability index is taken as a measure for the deviation of the actual path of a coupler point from the desir... A reliability-based analysis approach to mechanical error in path generating linkages is pre- sented . The reliability index is taken as a measure for the deviation of the actual path of a coupler point from the desired one. A reliability-based synthesis procedure of the mechanical error for path generating linkages to allocate optimal tolerances and clearances is developed. A four-bar path generating mechanism is considered for numerical illustration. 展开更多
关键词 Four-bar mechanism Path generating mechanism RELIABILITY SYNTHESIS
全文增补中
STUDY OF REGULARITY OF GENERAL-LINEAR-COMPLEX SINGULARITY OF 3/6-STEWART MECHANISM 被引量:1
13
作者 Li Yanwen Huang ZhenRobotics research Center,Yanshan University,Qinhuangdao 066004, China 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2003年第3期325-328,共4页
The general-linear-complex singularity of Stewart mechanism is a veryimportant problem in the parallel manipulator. Its general regularity is not found yet during thepast two decades. St-Onge and Gosselin pointed Out ... The general-linear-complex singularity of Stewart mechanism is a veryimportant problem in the parallel manipulator. Its general regularity is not found yet during thepast two decades. St-Onge and Gosselin pointed Out that the singularity locus of the Stewartmechanism at some given orientations of the moving platform should be polynomial expressions withvaried degrees in 2000, but they didn't formulate the expression. Based on the kinematicssingularity principle and the geometry condition proposed by Huang Zhen in 1999, firstly thesingularity equation in degree two is derived. It is a hyperbola when the orientation of the movingplatform is given. This result is also proved using screw theory. Then some singularity surfaces aregotten in three-dimensional space. This result is of important significance. 展开更多
关键词 Stewart mechanism general-linear-complex Singular configuration
下载PDF
Integrating Automatic Patch Snatching System by the Concept of Generalized Mechanisms
14
作者 裘建新 林兰天 沈逸平 《Journal of Donghua University(English Edition)》 EI CAS 2008年第2期235-240,共6页
An automatic patch snatching system is described which has three machine cells including dividing equipment, tackling equipment and patch removing equipment. The electromechanical integration design of in-piece tackli... An automatic patch snatching system is described which has three machine cells including dividing equipment, tackling equipment and patch removing equipment. The electromechanical integration design of in-piece tackling system based on the concept of generalized mechanisms is introduced. The design of the dividing equipment, the design of micro-feeding machine equipped with micro-level pressure sensor, and the realizing of computer path for patch snatching are investigated. 展开更多
关键词 PATCH snatching generalized mechanisms electromechanical integration design
下载PDF
Mathematical Model and Geometrical Model of Double Pitch ZN-type Worm Gear Set Based on Generation Mechanism 被引量:2
15
作者 SHU Linsen CAO Huajun +2 位作者 LI Xianchong ZHANG Chenglong LI Yuxia 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2015年第3期549-555,共7页
The current researches on the tooth surface mathematical equations and the theory of gearing mainly pay attention to the ordinary type worm gear set(e.g., ZN, ZA, or ZK). The research of forming mechanism and three-... The current researches on the tooth surface mathematical equations and the theory of gearing mainly pay attention to the ordinary type worm gear set(e.g., ZN, ZA, or ZK). The research of forming mechanism and three-dimensional modeling method for the double pitch worm gear set is not enough. So there are some difficulties in mathematical model deducing and geometry modeling of double pitch ZN-type worm gear set based on generation mechanism. In order to establish the mathematical model and the precise geometric model of double pitch ZN-type worm gear set, the structural characteristics and generation mechanism of the double pitch ZN-type worm gear set are investigated. Mathematical model of the ZN-type worm gear set is derived based on its generation mechanism and the theory of gearing. According to the mathematical model of the worm gear set which has been developed, a geometry modeling method of the double pitch ZN-type worm and worm gear is presented. Furthermore, a geometrical precision calculate method is proposed to evaluate the geometrical quality of the double pitch worm gear set. As a result, the maximum error is less than 6′10–4 mm in magnitude, thus the model of the double pitch ZN-type worm gear set is available to meet the requirements of finite element analysis and engineering application. The derived mathematical model and the proposed geometrical modeling method are helpful to guiding the design, manufacture and contact analysis of the worm gear set. 展开更多
关键词 double pitch ZN-type worm gear set generation mechanism mathematical model geometrical model
下载PDF
Algebraic Solution for the Forward Displacement Analysis of the General 6-6 Stewart Mechanism 被引量:8
16
作者 WEI Feng WEI Shimin +1 位作者 ZHANG Ying LIAO Qizheng 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2016年第1期56-62,共7页
The solution for the forward displacement analysis(FDA) of the general 6-6 Stewart mechanism(i.e., the connection points of the moving and fixed platforms are not restricted to lying in a plane) has been extensive... The solution for the forward displacement analysis(FDA) of the general 6-6 Stewart mechanism(i.e., the connection points of the moving and fixed platforms are not restricted to lying in a plane) has been extensively studied, but the efficiency of the solution remains to be effectively addressed. To this end, an algebraic elimination method is proposed for the FDA of the general 6-6 Stewart mechanism. The kinematic constraint equations are built using conformal geometric algebra(CGA). The kinematic constraint equations are transformed by a substitution of variables into seven equations with seven unknown variables. According to the characteristic of anti-symmetric matrices, the aforementioned seven equations can be further transformed into seven equations with four unknown variables by a substitution of variables using the Grobner basis. Its elimination weight is increased through changing the degree of one variable, and sixteen equations with four unknown variables can be obtained using the Grobner basis. A 40th-degree univariate polynomial equation is derived by constructing a relatively small-sized 9 × 9 Sylvester resultant matrix. Finally, two numerical examples are employed to verify the proposed method. The results indicate that the proposed method can effectively improve the efficiency of solution and reduce the computational burden because of the small-sized resultant matrix. 展开更多
关键词 general 6-6 Stewart mechanism forward displacement analysis (FDA) conformal geometric algebra (CGA) Gr6bner basis Sylvester resultant
下载PDF
Analysis on Physical Mechanism of Sound Generation inside Cavities Based on Acoustic Analogy Method 被引量:7
17
作者 Dangguo Yang Jianqiang Li +2 位作者 Jun Liu Yi Zhang Yaohua Li 《Open Journal of Fluid Dynamics》 2013年第1期23-31,共9页
Analysis of coupling aerodynamics and acoustics are performed to investigate the self-sustained oscillation and aerodynamic noise in two-dimensional flow past a cavity with length to depth ratio of 2 at subsonic speed... Analysis of coupling aerodynamics and acoustics are performed to investigate the self-sustained oscillation and aerodynamic noise in two-dimensional flow past a cavity with length to depth ratio of 2 at subsonic speeds. The large eddy simulation (LES) equations and integral formulation of Ffowcs-Williams and Hawings (FW-H) are solved for the cavity with same conditions as experiments. The obtained density-field agrees well with Krishnamurty’s experimental schlieren photograph, which simulates flow-field distributions and the direction of sound wave radiation. The simulated self-sustained oscillation modes inside the cavity agree with Rossiter’s and Heller’s predicated results, which indicate frequency characteristics are obtained. Moreover, the results indicate that the feedback mechanism that new shedding-vortexes induced by propagation of sound wave created by the impingement of the shedding-vortexes in the shear-layer and rear cavity face leads to self-sustained oscillation and high noise inside the cavity. The peak acoustic pressure occurs in the first oscillation mode and the most of sound energy focuses on the low-frequency region. 展开更多
关键词 CAVITY Physical mechanism SOUND generation Aerodynamic Noise SOUND PRESSURE Level SOUND PRESSURE Frequency SPECTRUM
下载PDF
New Approach to Synchronize General Relativity and Quantum Mechanics with Constant “K”-Resulting Dark Matter as a New Fundamental Force Particle
18
作者 Siva Prasad Kodukula 《Journal of High Energy Physics, Gravitation and Cosmology》 CAS 2024年第1期292-302,共11页
Planck scale plays a vital role in describing fundamental forces. Space time describes strength of fundamental force. In this paper, Einstein’s general relativity equation has been described in terms of contraction a... Planck scale plays a vital role in describing fundamental forces. Space time describes strength of fundamental force. In this paper, Einstein’s general relativity equation has been described in terms of contraction and expansion forces of space time. According to this, the space time with Planck diameter is a flat space time. This is the only diameter of space time that can be used as signal transformation in special relativity. This space time diameter defines the fundamental force which belongs to that space time. In quantum mechanics, this space time diameter is only the quantum of space which belongs to that particular fundamental force. Einstein’s general relativity equation and Planck parameters of quantum mechanics have been written in terms of equations containing a constant “K”, thus found a new equation for transformation of general relativity space time in to quantum space time. In this process of synchronization, there is a possibility of a new fundamental force between electromagnetic and gravitational forces with Planck length as its space time diameter. It is proposed that dark matter is that fundamental force carrying particle. By grand unification equation with space-time diameter, we found a coupling constant as per standard model “α<sub>s</sub>” for that fundamental force is 1.08 × 10<sup>-23</sup>. Its energy calculated as 113 MeV. A group of experimental scientists reported the energy of dark matter particle as 17 MeV. Thorough review may advance science further. 展开更多
关键词 general Relativity Quantum mechanics Space Time Dark Matter A New Fundamental Constant “K”
下载PDF
Hydrocarbon generation and storage mechanisms of deepwater shelf shales of Ordovician Wufeng Formation–Silurian Longmaxi Formation in Sichuan Basin, China 被引量:11
19
作者 GUO Xusheng LI Yuping +5 位作者 BORJIGEN Tenger WANG Qiang YUAN Tao SHEN Baojian MA Zhongliang WEI Fubin 《Petroleum Exploration and Development》 2020年第1期204-213,共10页
As the hydrocarbon generation and storage mechanisms of high quality shales of Upper Ordovician Wufeng Formation– Lower Silurian Longmaxi Formation remain unclear, based on geological conditions and experimental mode... As the hydrocarbon generation and storage mechanisms of high quality shales of Upper Ordovician Wufeng Formation– Lower Silurian Longmaxi Formation remain unclear, based on geological conditions and experimental modelling of shale gas formation, the shale gas generation and accumulation mechanisms as well as their coupling relationships of deep-water shelf shales in Wufeng–Longmaxi Formation of Sichuan Basin were analyzed from petrology, mineralogy, and geochemistry. The high quality shales of Wufeng–Longmaxi Formation in Sichuan Basin are characterized by high thermal evolution, high hydrocarbon generation intensity, good material base, and good roof and floor conditions;the high quality deep-water shelf shale not only has high biogenic silicon content and organic carbon content, but also high porosity coupling. It is concluded that:(1) The shales had good preservation conditions and high retainment of crude oil in the early times, and the shale gas was mainly from cracking of crude oil.(2) The biogenic silicon(opal A) turned into crystal quartz in early times of burial diagenesis, lots of micro-size intergranular pores were produced in the same time;moreover, the biogenic silicon frame had high resistance to compaction, thus it provided the conditions not only for oil charge in the early stage, but also for formation and preservation of nanometer cellular-like pores, and was the key factor enabling the preservation of organic pores.(3) The high quality shale of Wufeng–Longmaxi Formation had high brittleness, strong homogeneity, siliceous intergranular micro-pores and nanometer organic pores, which were conducive to the formation of complicated fissure network connecting the siliceous intergranular nano-pores, and thus high and stable production of shale gas. 展开更多
关键词 hydrocarbon generation and STORAGE mechanism Upper ORDOVICIAN Wufeng FORMATION Lower SILURIAN Longmaxi FORMATION deep-water SHELF siliceous shale Sichuan Basin pore preservation
下载PDF
Formation mechanism of tight sandstone gas in areas of low hydrocarbon generation intensity: A case study of the Upper Paleozoic in north Tianhuan depression in Ordos Basin, NW China 被引量:1
20
作者 ZHANG Fudong LI Jun +8 位作者 WEI Guoqi LIU Xinshe GUO Jianying LI Jian FAN Liyong SHE Yuanqi GUAN Hui YANG Shen SHAO Liyan 《Petroleum Exploration and Development》 2018年第1期79-87,共9页
The Upper Paleozoic in the north part of Tianhuan depression in the Ordos Basin,NW China has lower hydrocarbon generation intensity and complex gas-water relationship,the main factors controlling the formation of tigh... The Upper Paleozoic in the north part of Tianhuan depression in the Ordos Basin,NW China has lower hydrocarbon generation intensity and complex gas-water relationship,the main factors controlling the formation of tight sandstone gas and the distribution of tight sandstone gas in the low hydrocarbon generation intensity area are studied.Through two-dimensional physical simulation experiment of hydrocarbon accumulation,analysis of reservoir micro-pore-throat hydrocarbon system and dissection of typical gas reservoirs,the evaluation models of gas injection pressure,reservoir physical property,and gas generation threshold were established to determine the features of tight gas reservoirs in low hydrocarbon intensity area:(1)at the burial depth of less than 3 000 m,the hydrocarbon generation intensity ofis high enough to maintain effective charging;(2)tight sandstone in large scale occurrence is conducive to accumulation of tight gas;(3)differences in reservoir physical property control the distribution of gas pool,for the channel sandstone reservoirs,ones with better physical properties generally concentrate in the middle of sandstone zone and local structural highs;ones with poor physical properties have low gas content generally.Based on the dissection of the gas reservoir in the north Tianhuan depression,the formation of tight gas reservoirs in low hydrocarbon generating intensity area are characterized by"long term continuous charging under hydrocarbon generation pressure,gas accumulation in large scale tight sandstone,pool control by difference in reservoir physical property,and local sweet spot",and the tight gas pools are distributed in discontinuous"sheets"on the plane.This understanding has been proved by expanding exploration of tight sandstone gas in the north Tianhuan depression. 展开更多
关键词 ORDOS Basin Tianhuan DEPRESSION hydrocarbon generation INTENSITY tight SANDSTONE gas reservoir-forming mechanism distribution pattern
下载PDF
上一页 1 2 231 下一页 到第
使用帮助 返回顶部