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Operations Research, Systems Engineering and Industrial Engineering

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Articles 3631 - 3660 of 3973

Full-Text Articles in Systems Science

Lateral Force Measurement And Processing Of Planar Air-Bearing System For Microgravity Simulation, Xinfeng Li, Xiang Dong, Xinghua Tian, Wei Wei Jan 2019

Lateral Force Measurement And Processing Of Planar Air-Bearing System For Microgravity Simulation, Xinfeng Li, Xiang Dong, Xinghua Tian, Wei Wei

Journal of System Simulation

Abstract: An approach of direct force measurement is proposed to estimate the lateral force of a planar air cushion system. Lateral force gauges are arranged around the planar air bearing platform with preloading force exerted before afloat. Lateral force and its torque with respect to the geometric center can be obtained from the gauge variations while the afloat system reaches balance. Friction coefficient in every touch-spot can be evaluated with least square state estimation, which changes to a generic minimum problem with constraints since its solution matrix has a rank deficit. The analysis based on the test of a specified …


Apt-Oriented Dynamic Assessment Of Attack Behaviors, Jindong Wang, Haopu Yang, Hengwei Zhang, Li Tao Jan 2019

Apt-Oriented Dynamic Assessment Of Attack Behaviors, Jindong Wang, Haopu Yang, Hengwei Zhang, Li Tao

Journal of System Simulation

Abstract: The existing attack assessment methods cannot effectively deal with the long-term concealment in APT attack. Aiming at the accurate assessment of attack behaviors in APT attack, the APT-oriented dynamic assessment of attack behaviors which focuses on both the space dimension and the time dimension is proposed. The attack behaviors are correlated in the causality-diversion among the whole network system to discover the attack paths. The attack paths are modified in the time-diversion to get the dynamic causal attack traces. The attack traces are quantified based on CVSS standard. The experimental result shows that the proposed method can correctly …


Optimizing Initial Cluster Centroids By Svd In K-Means Algorithm For Chinese Text Clustering, Yueming Dai, Minghui Wang, Zhang Ming, Wang Yan Jan 2019

Optimizing Initial Cluster Centroids By Svd In K-Means Algorithm For Chinese Text Clustering, Yueming Dai, Minghui Wang, Zhang Ming, Wang Yan

Journal of System Simulation

Abstract: In process of clustering with traditional K-means algorithm, it is difficult to identify the value of the number of clusters K and its clustering results are influenced by initial centers. It has the weakness of sensitivity to noise and instability. Meanwhile, to solve the problems for the high dimensions, sparse spatial and latent semantic structure of the text data, an algorithm for Chinese text clustering was proposed. This new algorithm uses the physical significance of Singular Value Decomposition (SVD) to firstly classify the data rough, and then uses K-means for text clustering. It applies SVD to decompose and keep …


Simulation On Transaction Connection Strength Considering Price Preference, Zheng Wen, Yapeng Li, Yingying Ma Jan 2019

Simulation On Transaction Connection Strength Considering Price Preference, Zheng Wen, Yapeng Li, Yingying Ma

Journal of System Simulation

Abstract: Under LDP (Large-user Direct purchase) mode of power system, interests of the imbalance distribution exist in the power system in the long-term, due to the sensitivity of the larger user to the price to a certain extent. The impact of price preference on the transaction connection strength is analyzed, constructing the states of the interest distribution by using the Swarm simulation platform. The results of the simulation suggest that the higher the priority probability is, the more concentrated the power system becomes. It shows the non-natural monopoly caused by the market power. The results of this study can be …


Mechanism Of Biofouling Control On Micro-Structured Surface, Chunxi Li, Quanxi Xue, Zhang Shuo, Xuemin Ye Jan 2019

Mechanism Of Biofouling Control On Micro-Structured Surface, Chunxi Li, Quanxi Xue, Zhang Shuo, Xuemin Ye

Journal of System Simulation

Abstract: Changing the wall microstructure geometry can improve the performance of surface antifouling and selfcleaning. A 3D numerical simulation of microfluidic in the near-wall region attached with microorganisms is performed with Fluent, and the kinetic and dynamic characteristics of fluid in the near- wall region are examined. The inherent mechanism of antifouling on microwell surfaces is discussed. Results reveal that streamwise vortices are formed in the microwells, thus the distinctly periodic fluctuations of velocity, strain rate and wall shear stress on microwell surfaces are exhibited, resulting in the interference on microorganisms migration and the harder adhesion of microorganisms to …


Optimization Of Tip Clearance Patterns Of Variable-Pitch Axial Flow Fan, Xuemin Ye, Jianguang Cui, Chunxi Li Jan 2019

Optimization Of Tip Clearance Patterns Of Variable-Pitch Axial Flow Fan, Xuemin Ye, Jianguang Cui, Chunxi Li

Journal of System Simulation

Abstract: The performance of the axial fan can be improved by optimization of blade tip pattern effectively. For a variable pitch axial flow fan of OB-84 type, the performance of the fan with uniform tip clearance and non-uniform tip clearance are simulated by using Fluent. The impacts of tip patterns on leakage flow field and loss distribution in the tip clearance are examined. The results reveal that when average tip clearance keeps constant, the total pressure rise and efficiency of the fan with convergent tip clearance patterns are higher than those of uniform tip clearance, and the domain of higher …


Predator-Prey Dynamics-Based Optimization, Qiuqin Lu, Guangqiu Huang Jan 2019

Predator-Prey Dynamics-Based Optimization, Qiuqin Lu, Guangqiu Huang

Journal of System Simulation

Abstract: To solve the complex function optimization problem, a predator-prey dynamics optimization algorithm is proposed. The algorithm assumes that there are two species of predator and prey in an ecosystem. There is competition among the same species, the higher the population density, the more intense the competition, and then characteristics of populations are more likely to produce changes; strong populations are more likely to defeat weak populations when competition, and thus to obtain significant changes in their own characteristics. When predator populations eat prey populations, their characteristics also change. The competition operator, the predator-prey operator and the growth operator are …


Event Triggered Optimization Method For Dynamic Task Decomposition Mode In Cloud Fusion, Wang Yan, Lijun Cheng Jan 2019

Event Triggered Optimization Method For Dynamic Task Decomposition Mode In Cloud Fusion, Wang Yan, Lijun Cheng

Journal of System Simulation

Abstract: Aiming at the characteristics of randomness, dynamics, diversity and uncertainty of arrival time in the cloud fusion mode, two triggered tasks of the new tasks randomly reaching the cloud platform and the non-executable sub-tasks are considered. To improve the sub-tasks correlation degree and the workload balance of each group, the coupling degree of the sub-tasks is decreased, and an event-triggered mechanism (ETM) based optimization method for dynamic task decomposition mode is proposed. On the basis of the unified tasks description, the optimal flow of dynamic task decomposition is designed to determine the sub-tasks information flow. A multi-objective …


Research On Evaluation Framework Of Coa Based On Wargaming, Haiyang Liu, Yubo Tang, Xiaofeng Hu, Guangpeng Qiao Jan 2019

Research On Evaluation Framework Of Coa Based On Wargaming, Haiyang Liu, Yubo Tang, Xiaofeng Hu, Guangpeng Qiao

Journal of System Simulation

Abstract: Aiming at the evaluation problem of COA (course of action) level indicators in joint operation, an evaluation framework of COA based on wargaming was proposed. By multidimensional analysis of wargaming data, an evaluation feature space was constructed from basic features generated by data cube models and SoS (system of systems) features based on complex network. Wargaming experiments were used to generate small batch metrics results of COA level indicators, and the corresponding result labels of evaluation feature space data were generated by data fitting method. Two-phase correlation analysis was used for dimensionality reduction of high dimensional evaluation features. …


Intelligent Technology Of Command And Control System In The Rts Perspective, Wenfeng Wu, Zhang Yu, Rong Ming Jan 2019

Intelligent Technology Of Command And Control System In The Rts Perspective, Wenfeng Wu, Zhang Yu, Rong Ming

Journal of System Simulation

Abstract: Real-Time Strategy (RTS) games have important reference value for studying the intelligent technology of command and control systems. The similarities between RTS games and the strategic battle level command and control systems are described according to the decision process. The challenges brought by the problems of planning, learning, uncertainty and space-time reasoning in the intelligent technology of RTS games are analyzed. The key technologies and latest research progress of action sequence planning, plan recognition, state assessment, multi-agent collaboration and multi-scale AI are studied. The trend of intelligent technology development of strategic and operational level command and control systems is …


Extensible Battle Management Ontology Language, Zaijiang Tang, Xiangzhong Xue, Xue Qin Jan 2019

Extensible Battle Management Ontology Language, Zaijiang Tang, Xiangzhong Xue, Xue Qin

Journal of System Simulation

Abstract: The interoperability of command and control system with combat simulation system is an important and difficult problem in the construction of practical training environment. Aiming at the existing problems of semantic interoperability of language description, the battle management language, web ontology language and extensible markup language are studied. Based on ontology theory, the extensible battle management ontology language (XBMOL) is proposed. The syntax structure and semantic annotation of XBMOL are analyzed as an extension to the C-BML. The XBMOL 6W1H architecture is designed, and the extensible grammatical structure and semantic tagging are described. An example with XBMOL is given …


Visual Object Tracking Algorithm Based On Deep Denoising Autoencoder Over Rgb-D Data, Mingxin Jiang, Zhigeng Pan, Lanfang Wang, Taoxin Hu Jan 2019

Visual Object Tracking Algorithm Based On Deep Denoising Autoencoder Over Rgb-D Data, Mingxin Jiang, Zhigeng Pan, Lanfang Wang, Taoxin Hu

Journal of System Simulation

Abstract: A visual object tracking algorithm based on cross-modality features deep learning over RGB-D data is proposed. A sparse denoising autoencoder deep learning network is constructed, which can extract cross-modal features of the samples in RGB-D video data. The cross-modal features of the samples are input to the logistic regression classifier, the observation likelihood model is established according to the confidence score of the classifier, and the reasonable state transition model is established. The object tracking results over RGB-D data are obtained using particle filtering algorithm. Experimental results show that the proposed method has strong robustness to abnormal changes. …


Service Recommended Trust Algorithm Based On Cloud Model Attributes Weighted Clustering, Jindong Wang, Zhiyong Yu, Hengwei Zhang, Fang Chen Jan 2019

Service Recommended Trust Algorithm Based On Cloud Model Attributes Weighted Clustering, Jindong Wang, Zhiyong Yu, Hengwei Zhang, Fang Chen

Journal of System Simulation

Abstract: In cloud computing, there are cloud services of different qualities. How to choose credible and reliable service has become a key issue when users select services. Aiming at the shortcomings of the existing evaluation methods, a service clustering method based on attributes weighted cloud model is proposed. The users’ evaluation similarity with weighted Pearson correlation coefficient method based on service clustering is calculated. The users’ similarity combined with the index weights of users’ service selection is computed. The nearest neighbors are gotten. The recommendation trust of the services with the recommendation trust algorithm is obtained. Simulation results …


Simulation Data-Driven Modeling Approach For Space Information Network, Yang Xing, Wu Jing, Jianguo Zhou, Jiang Hao, Zhu Jie Jan 2019

Simulation Data-Driven Modeling Approach For Space Information Network, Yang Xing, Wu Jing, Jianguo Zhou, Jiang Hao, Zhu Jie

Journal of System Simulation

Abstract: Aiming at the problem for the research on the simulation and modeling of the space information network (SIN) with high complexity, a SIN modeling approach based on simulation data is proposed. On this basis, a deep predictive auto-encoder network for SIN performance indicators and a hybrid forecasting analysis model with random forest regression are designed. Due to the characteristics of high dimensionality and wide distribution of SIN performance indicators, with using the deep learning auto-encoder network, the construction of SIN performance index is realized. Combined with the random forest regression model, the relationship model between the network design parameters …


Two-Sided Matching Decision Model Between Task And Resource For Cloud Fusion, Lijun Cheng, Wang Yan Jan 2019

Two-Sided Matching Decision Model Between Task And Resource For Cloud Fusion, Lijun Cheng, Wang Yan

Journal of System Simulation

Abstract: The disjointing of cloud task-to-resource matching link is a prominent problem in the cloud fusion process. Aiming at this problem, a cloud-based fusion task assignment model optimization method based on the improved knowledge migration maximum entropy clustering algorithm (KT-MECA) is proposed, in which the two-sided satisfaction of tasks and resources is considered. The algorithm improves the introduction of historical clustering center knowledge and membership degree knowledge, improves clustering performance and stability, and solves the problem that traditional clustering algorithms cannot be applied to dynamic cloud resource clustering. Considering the two-side subject satisfaction, the result of KT-MECA is applied to …


Improved Intrusion Weed Algorithm For Solving Flexible Job Shop Scheduling Problem, Zhang Xin, Li Ke, Dahu Yan, Zhicheng Ji Jan 2019

Improved Intrusion Weed Algorithm For Solving Flexible Job Shop Scheduling Problem, Zhang Xin, Li Ke, Dahu Yan, Zhicheng Ji

Journal of System Simulation

Abstract: An improved invasive weed optimization algorithm is proposed for solving multi-objective flexible job shop scheduling problem (FJSP) with released time and delivery date. The minimum completion time of jobs, the maximum work load of machines and the total work load of all machines are taken as the optimization goals to establish a FJSP model. A random key encoding scheme based on transformed sequences is proposed and a mapping relationship is set up between the continuous space and the discrete space of FJSP. An adaptive Gauss mutation operator is introduced to diversify the population in the process of weed breeding. …


Indoor Positioning Algorithm Based On Zigbee And Improved Radio Frequency Identification, Dahu Yan, Yangjie Xu Jan 2019

Indoor Positioning Algorithm Based On Zigbee And Improved Radio Frequency Identification, Dahu Yan, Yangjie Xu

Journal of System Simulation

Abstract: Since the traditional RFID positioning technology relies on the Internet and is especially constrained by the positioning distance in the process of positioning the tags with poor positioning accuracy, a novel positioning algorithm is proposed based on the ZigBee and improved VIRE algorithm. By using the proposed algorithm, ZigBee nodes are adopted to achieve the formation of network information transmission to replace the traditional wired communication. Gaussian-Kalman filter is used to deal with the sampling data of the limited preselected reference node signal strength. The algorithm adopts signal propagation loss model to calculate the RSSI values of virtual reference …


Motif-Based Intelligent Mission Planning Method For Uav Swarms, Weiping Wang, Wang Tao, Xiaobo Li, Jiajie Liu Jan 2019

Motif-Based Intelligent Mission Planning Method For Uav Swarms, Weiping Wang, Wang Tao, Xiaobo Li, Jiajie Liu

Journal of System Simulation

Abstract: Due to the restriction of communication among UAV swarms, configuration of UAV swarms needs to be changed dynamically along with the task changes. How to do mission planning under limited communication for UAV swarms has become a hot and difficult question. The UAV combat network motif model framework is built based on the function, and six different types of basic motif model are proposed. Through capability demand and communication demand, a task is mapped into types and numbers of motifs which are required to complete the task. The ‘multidimensional dynamic scheduling list’ method is used to automatically generate mission …


A Hierarchical Control Framework And Key Algorithms Of Multi-Swarm Persistent Surveillance, Wang Tao, Weiping Wang, Xiaobo Li, Jing Tian Jan 2019

A Hierarchical Control Framework And Key Algorithms Of Multi-Swarm Persistent Surveillance, Wang Tao, Weiping Wang, Xiaobo Li, Jing Tian

Journal of System Simulation

Abstract: Persistent surveillance is a typical application of multi-swarm aerial vehicle systems (UAVs). And dynamic deployment for multi-swarm UAVs in persistent surveillance has been proved to be a complex problem, especially when the self-adjustment is required to adapt the time-sensitive environment. This paper proposes a multi-swarm hierarchical control scheme and key algorithms. We design the digital turf potential field model to approximate the evolving and interactive information of time-sensitive target features and surveillance effects. Moreover, using the digital turf potential function of each grid as the data point weight, we design a grid-based weighted data-clustering algorithm for the dynamic assignment …


Modeling And Simulation Of Bank Network System With Internet Monetary Fund, Fan Hong, Wang Ke, Zhijie Wang Jan 2019

Modeling And Simulation Of Bank Network System With Internet Monetary Fund, Fan Hong, Wang Ke, Zhijie Wang

Journal of System Simulation

Abstract: There are some internet monetary funds such as “Yuebao” becoming an important part of banking system in China in recent years. What kinds of the characteristics and stability of the banking system running are the most urgent problem needed to be solved. Based on the method of the network system dynamics, the dynamical relationship between the internet money fund and traditional bank network is analyzed, and a dynamical algorithm and process of borrowing-lending are provided. A simulation model of banking network system with the internet monetary fund is constructed, which can realize the running process of the banking network …


Modeling And Simulation Of Missile Defense M/M/N Queueing System, Longyue Li, Fuxian Liu, Huizhen Zhao Jan 2019

Modeling And Simulation Of Missile Defense M/M/N Queueing System, Longyue Li, Fuxian Liu, Huizhen Zhao

Journal of System Simulation

Abstract: To simulate the process of ballistic missile defense and to study the effectiveness of defense, the M/M/N queueing system of missile defense was modeled and simulated. A queueing modeling framework was given to explain the meaning and distribution of related parameters. The M/M/N/N and M/M/N/C queueing models were proposed for short defense depth and long defense depth respectively, and the single target channel and the multiple target channels were distinguished in each model. How to deal with the different types of missile defense system based on equivalent replacement method were also considered. Simulation examples verified the main …


Soft Shadow Rendering Algorithm Based On Gpu’S Shadow Line, Shanxiao Gao, Wu Xian Jan 2019

Soft Shadow Rendering Algorithm Based On Gpu’S Shadow Line, Shanxiao Gao, Wu Xian

Journal of System Simulation

Abstract: To solve the problem of soft shadow rendering algorithm on shaded body surfaces, a new algorithm based on shadow lines which can render better soft shadow with less cost computation overhead is presented. GPU is used to create shadow lines which include starting point, ending point and shading value. The computer shader (CS) is used to amend the shading value by inverse distance weighting function. In the phase of shadow rendering, the shadow lines dataset is used to calculate the current pixel's shading value by trigonometric interpolation. Experimental result shows that the algorithm can solve the soft shadow …


Simulation And Analysis Of Forced Caving Blasting Scheme For Overburden Steep Inclined Strata In Coal Mining, Tiejun Cui, Yundong Ma, Laigui Wang Jan 2019

Simulation And Analysis Of Forced Caving Blasting Scheme For Overburden Steep Inclined Strata In Coal Mining, Tiejun Cui, Yundong Ma, Laigui Wang

Journal of System Simulation

Abstract: According to the actual situation of overburden steep inclined strata with horizontal fracture, the reasonable goaf forced caving blasting schemes are studied. Considering overburden characteristic and representative, two schemes are put forward with the attachment perpendicular to their break point locations. By setting different places of blasting points, the different directions of blasting and blasting area are determined, and the overlying strata movement and development characteristics of blasting fracture are analyzed. The overlying strata movement range is larger and can develop to the surface after blasting; The conclusion is that the influence range of the fracture is wide in …


Flow Field Analysis Of Pipeline Pig Receiving Trap, Chuanjun Han, Yu Cheng, Xingzhi Duan, Li Qi Jan 2019

Flow Field Analysis Of Pipeline Pig Receiving Trap, Chuanjun Han, Yu Cheng, Xingzhi Duan, Li Qi

Journal of System Simulation

Abstract: To study the influence of piping diameter on the flow field characteristics when pig receiving trap is working, the finite element model of pig receiving trap whose type is P6.3MPa DN700/DN600 was established, and the effects of the diameters changes of vent pipe and blow-off pipe were simulated. The effects caused by the pig running speeds on the flow field of the pig receiving trap were studied. The results show that in the pig receiving trap, there is the maximum pressure in the left side of pig staying and the pressure begins to decrease and easy to form swirls …


Risk Analysis Of Semitrailer Overtaking On Curved Sections Based On Dynamic Simulation, Zhang Chi, Qi Chen, Xiaomin Yan, Dongjian Shao, Zhang Min Jan 2019

Risk Analysis Of Semitrailer Overtaking On Curved Sections Based On Dynamic Simulation, Zhang Chi, Qi Chen, Xiaomin Yan, Dongjian Shao, Zhang Min

Journal of System Simulation

Abstract: To study the safety of semitrailers corner overtaking behavior, the dynamic model of vehicle, the road model and the drivers' aiming trajectory model were developed by multi-body dynamics simulation software TruckSim. The semitrailers were simulated in separate working conditions by changing the super-elevations, circular curve radius, vehicle turning radius and speed. Lateral load transfer rate was invoked as the evaluation index for evaluating the vehicle's safety. The model of six axle semitrailer side tumbling stability prediction was established through the Spss regression; the risk of overtaking on five separate bends of a western highway was evaluated by the model. …


De-Noising Method Of Eeg Signal Based On Mmtd And Wavelet Hard-Threshold, Guoqiang Yan, Ningning Zhou, Shaobai Zhang Jan 2019

De-Noising Method Of Eeg Signal Based On Mmtd And Wavelet Hard-Threshold, Guoqiang Yan, Ningning Zhou, Shaobai Zhang

Journal of System Simulation

Abstract: To overcome the shortage of losing partial important information of hard-threshold method with EEG signal de-noising process, a novel de-noising method based on the combination of measuring of medium truth degree (MMTD) and EEG is proposed. By decomposing noisy signals of wavelet transform, handling threshold of high-frequency wavelet coefficients in every layer, and reconstructing post-processing of the wavelet coefficients, the purpose of noise elimination can be guaranteed. Under different noise intensity, the experimental results show that the MAWH (MMTD and wavelet hard-threshold) method has perspective of lower RMSE and higher SNR compared to hard-threshold and soft-threshold.


Important Object Recognition Method For C4Isr System Based On Operation Traffic Mining, Zhou Fang, Chu Wei, Wendi Cheng Jan 2019

Important Object Recognition Method For C4Isr System Based On Operation Traffic Mining, Zhou Fang, Chu Wei, Wendi Cheng

Journal of System Simulation

Abstract: Considering the problem of vital object recognition for C4ISR system under confrontation condition, a vital object recognition method based on operation traffic mining is proposed. The system operation traffics are collected, the operation data packet describing model is established based on six attribute group described method. The operation traffic association matrix and connectivity matrix are built based on the source IP and destination IP address on data packet. The inflow and outflow operation traffics about system node are counted, and the system vital computation model is established based on statistical traffics as the measurement criteria of system …


Satisfactory Fault-Tolerant Control Of Nncs Under Event-Triggered Sparse Data Transmission, Yajie Li, Li Wei Jan 2019

Satisfactory Fault-Tolerant Control Of Nncs Under Event-Triggered Sparse Data Transmission, Yajie Li, Li Wei

Journal of System Simulation

Abstract: Adopting the discrete event-triggered communication scheme (DETCS), the satisfactory fault-tolerant control of nonlinear networked control system (NNCS) under the sparse data transmission circumstance was studied. Based on the background of event-triggered sparse data transmission, a closed-loop model with actuator failure and actuator saturation was established. Based on Lyapunov-Krasovskii function and the safety degree definition proposed in this paper, a sufficient condition was presented for NNCS with the generalized H?/H2 performance under the case of actuator saturation and actuator failure, which was the contractively invariant set of fault-tolerance with α-safety degree, and …


Sliding Backstepping Mode Control For Flight Simulator Servo Based On Disturbance Compensation And Differentiator, Huibo Liu, Shanglei Liu Jan 2019

Sliding Backstepping Mode Control For Flight Simulator Servo Based On Disturbance Compensation And Differentiator, Huibo Liu, Shanglei Liu

Journal of System Simulation

Abstract: Considering the uncertain factors in flight simulator servo system, such as friction torque and modeling error, a sliding backstepping mode control strategy based on the nonlinear extended state observer (NESO) and differentiator was put forward. The uncertain factors were defined as compound disturbances, and the NESO was used for observations in combination with real-time compensations that reduced impact on the system brought by disturbances. Differentiator was used to estimate the system state variables, hence preventing the noise amplifications caused by the difference method; law design came under the control of a sliding backstepping mode controller designed in accordance with …


Aerodynamic Noise Generating Mechanism Of Corbula Type Throttle Valves, Yueqin Li, Xiao Fei, Fan Ming, Xiaodong Xu Jan 2019

Aerodynamic Noise Generating Mechanism Of Corbula Type Throttle Valves, Yueqin Li, Xiao Fei, Fan Ming, Xiaodong Xu

Journal of System Simulation

Abstract: The throttle mechanism of pneumatic noise and the noise spectrum characteristics of corbula type throttle valve are studied by targeting on aerodynamic noise problems caused by gas when flowing through the corbula type throttle valve, the method of CFD software with acoustic software simulationis used as well. The studies have showed that when the flow of fluid flows through shrink section, it can be effected by throttling effect, the speed of gas on the hole exit increases rapidly to form under-expanded supersonic jet, causing strong turbulence and shock wave noise. The conclusionis that the construction of throttling …