Envelope to a Two-Parameter Family of Point Vectors Method for Surface Swept by Form Wheel

2014 ◽  
Vol 494-495 ◽  
pp. 563-568
Author(s):  
Yuan Zhi Peng ◽  
Kun He ◽  
Guo Long Li ◽  
Wei Zhang
Keyword(s):  
Analytical Calculation ◽  
Calculation Model ◽  
Parametric Family ◽  
Normal Vector ◽  
Accuracy Evaluation ◽  
Simulation Accuracy ◽  
Geometry Simulation ◽  
Latitude Circle ◽  
Two Parameter ◽  
Point Vector

The form wheel generating curve is always a composited curve which is composed of lines and arcs, and the calculation of the envelope surface is more complex than conventional rotary cutter. Therefore, a method of envelope to a two-parametric family of point vectors is proposed, which defines the point and its normal vector on the wheel generating curve as a point vector. Each point vector corresponds to a virtual ball uniquely. The rotation of point vector forms latitude circle and the valid envelopment movement forms sectional circle. The intersection of latitude circle and sectional circle is grazing point; The analytical calculation model is established, in which the geometry parameters of virtual ball can be directly calculated from point vector; An example is presented to demonstrate the effectiveness of the method which can be used for form grinding geometry simulation, accuracy evaluation and optimization of the wheel path.

scholarly journals Offshore Platform Extraction Using RadarSat-2 SAR Imagery: A Two-Parameter CFAR Method Based on Maximum Entropy

Entropy ◽  
2019 ◽  
Vol 21 (6) ◽  
pp. 556 ◽  
Author(s):  
Qi Wang ◽  
Jing Zhang ◽  
Fenzhen Su
Keyword(s):  
False Alarm ◽  
Maximum Entropy ◽  
Target Detection ◽  
Detection Threshold ◽  
River Estuary ◽  
Offshore Platform ◽  
Accuracy Evaluation ◽  
Oil And Gas Development ◽  
Offshore Oil ◽  
Two Parameter

The ability to determine the number and location of offshore platforms is of great significance for offshore oil spill monitoring and offshore oil and gas development. Considering the problem that the detection threshold parameters of the two-parameter constant false alarm rate (CFAR) algorithm require manual and repeated adjustment of the during the extraction of offshore platform targets, this paper proposes a two-parameter CFAR target detection method based on maximum entropy based on information entropy theory. First, a series of threshold parameters are obtained using the two-parameter CFAR algorithm for target detection. Then, according to the maximum entropy principle, the optimal threshold is estimated to obtain the target detection results of the possible offshore platform. Finally, the neighborhood analysis method is used to eliminate false alarm targets such as ships, and the final target of the offshore platform is obtained. In this study, we conducted offshore platform extraction experiments and an accuracy evaluation using data from the Pearl River Estuary Basin of the South China Sea. The results show that the proposed method for platform extraction achieves an accuracy rate of 97.5% and obtains the ideal offshore platform distribution information. Thus, the proposed method can objectively obtain the optimal target detection threshold parameters, greatly reduce the influence of subjective parameter setting on the extraction results during the target detection process and effectively extract offshore platform targets.

scholarly journals An analytical model to determine the impact force of drone strikes

2021 ◽  
Author(s):  
Florian Franke ◽  
Michael Schwab ◽  
Uli Burger ◽  
Christian Hühne
Keyword(s):  
Load Distribution ◽  
Impact Force ◽  
Analytical Calculation ◽  
Calculation Model ◽  
Material Behavior ◽  
Major Influence ◽  
Impact Model ◽  
Simulation Data ◽  
Input Parameters ◽  
The Impact

AbstractIn addition to the well-known threats of bird and hail strikes, small unmanned aerial vehicles (sUAV) pose a new threat to manned aviation. Determining the severity of collisions between sUAVs and aircraft structures is essential for the safe use and integration of drones in airspace. A generic analytical calculation model needs to be developed to supplement the existing test and simulation data. This paper presents an analytic model for drone collisions with perpendicular and inclined targets. The targets have a rigid or elastic material behavior. The aircraft impact model, which is used for the design of nuclear reactor structures, is transferred and adjusted for sUAV impacts to calculate the impact force. A mass- and a burst load distribution are needed as input parameters. Both distributions are determined for an sUAV design depending on the flight direction. Compared to previous calculations, the new approach is to consider a moving target structure, which produces more realistic results. We compare the calculation results with simulation data from sUAV collisions with a commercial airliner windshield from the literature. The calculations show plausible results and a good agreement with literature data. Subsequently, the influence of the input parameters on the impact force is investigated. We see that spring stiffness, target mass, burst load distribution and damping have minor influence on the overall impact force. The impact velocity, mass distribution and flight orientation on the other hand have a major influence on the impact force. Further tests are needed to validate the impact model.

Analytical calculation models for mesh stiffness and backlash of spur gears under temperature effects

2021 ◽  
pp. 095440622110498
Author(s):  
Ruxin Lu ◽  
Wencheng Tang
Keyword(s):  
Analytical Calculation ◽  
Calculation Model ◽  
Tooth Profile ◽  
Thermal Time ◽  
Time Varying ◽  
Mesh Stiffness ◽  
Profile Error ◽  
Gear Teeth ◽  
Influencing Mechanism ◽  
Torque Load

The temperature has a great contribution to the mesh stiffness and backlash of the gear pair. Presence of thermal deformation caused by temperature will complicate the gear teeth interaction. In this paper, the thermal time-varying stiffness model and thermal time-varying backlash model are proposed with the consideration of tooth profile error and total thermo-elastic deformation consists of the teeth deformation, teeth contact deformation, and gear body-induced deformation. The key parameters of thermo-elastic coupling deformation affected by temperature are calculated. Based on the proposed models, the influencing mechanism of temperature on the tooth profile error, mesh stiffness, total deformation, and backlash are revealed. The effects of shaft radius and torque load on the thermal stiffness and thermal backlash are studied. The proposed thermal stiffness and backlash calculation model are proven to be more comprehensive and the correctness is validated.

Flexible Pipe Curved Collapse Resistance Calculation

2009 ◽  
Author(s):  
Laurent Paumier ◽  
Daniel Averbuch ◽  
Antoine Felix-Henry
Keyword(s):  
Failure Modes ◽  
Analytical Calculation ◽  
External Pressure ◽  
Calculation Model ◽  
Third Party ◽  
Flexible Pipe ◽  
The Past ◽  
Curved Pipes ◽  
Pressure Resistance ◽  
Collapse Failure

In the design of flexible pipelines for offshore field developments, the determination of the pipe resistance while subjected to external pressure and bending is very important in deepwater and is now required by the ISO and API standards. One of the critical failure modes being associated with this type of loads is the hydrostatic collapse. The collapse value of flexible pipe is calculated with a model validated with over 200 tests performed on all possible pipe constructions. This model has an analytical basis, and has been established in the past, leading to a fast and straightforward use. In order to address the bent collapse failure mode, Technip and IFP have therefore developed and improved over the past few years an analytical calculation model, based on the collapse model for straight pipes. The purpose of this paper is to present this design methodology and its validation. The modelling principles of the collapse calculation of straight flexible pipes are firstly presented, along with the main hypotheses. The adaptation to the case of curved pipes is detailed in the sequel of the paper. Many types of flexible pipe samples have been tested up to collapse both in straight and curved configurations. The results of these tests have been used to validate this model. In the paper, several tests results will be presented and compared with the calculations. This model is effective, of straightforward use, and has been certified by a third party. It allows Technip to optimize the flexible pipe design in particular for ultra-deep water applications, where external pressure resistance is very important.

Comparative experimental and numerical study on energy consumption of track-pin rubber bushing for high-speed tracked vehicles

2019 ◽  
Vol 233 (13) ◽  
pp. 3480-3492
Author(s):  
Bing Chen ◽  
Lijie Zhang ◽  
Zhanzong Feng ◽  
Yuanyuan Du ◽  
Wei Mo ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Energy Loss ◽  
High Speed ◽  
Numerical Study ◽  
Analytical Calculation ◽  
Elastic Stiffness ◽  
Calculation Model ◽  
Tracked Vehicles ◽  
Modeling And Analysis ◽  
Rubber Bushing

During the running of high-speed tracked vehicles, the energy loss due to the rotation and tension-compression deformation of the rubber bushing between the track pin and the track plate causes the largest proportion of energy consumption in tracked vehicle propulsion systems; therefore, it is critical to study energy consumption of this component as it is the largest amount of energy loss of the system. First, the theoretical modeling and analysis of the torsional hysteresis and the tension-lag of the hanging glue on the pin of the track pin are conducted. Both energy loss of torsional hysteresis and energy loss of the hysteresis of tension and pressure are obtained when the rubber bushings pass the sprocket, the road wheel, and the idler. Second, a new and novel rubber bushing model based upon the rubber bushing elastic element, the friction element, and the viscoelastic element is proposed. Then the parameters (such as the static elastic stiffness and the maximum friction) of each unit are identified according to the dynamic characteristic experiment. Finally, the numerical simulation results of MATLAB with different stiffness and damping coefficient in addition to tension and compression energy consumption under different frequencies are obtained, and the comparisons are basically consistent with the experimental results; the average errors are less than 8%. The present analytical calculation model is practically useful and can meet the requirements of engineering applications.

scholarly journals Load capacity of the mixed bench and slab foundation. Numerical simulations and analytical calculation model

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Michał Grodecki
Keyword(s):  
Numerical Simulations ◽  
Analytical Model ◽  
Load Capacity ◽  
Analytical Calculation ◽  
Calculation Model ◽  
Engineering Practice ◽  
Safe Side ◽  
3D Numerical Modelling ◽  
Slab Foundation ◽  
Analytical Approaches

Abstract The paper presents results of a numerical investigation on load capacity of the mixed bench and slab shallow foundations (often used in the process of the modernization of the old, antique buildings, which are suffering from lack of the load capacity). The main trouble with use of existing analytical approaches is a non-unique foundation level of the bench and slab, they could even be founded on different geotechnical layers. Proposed analytical model based on Brinch Hansen (EC-7) approach could deal with such a problem. Results of 2D and 3D numerical modelling (ultimate load of the foundation) are compared to the obtained by using the proposed approach. Influence of the soil above the foundation level is also investigated. Different width to length ratios of the foundation are analyzed (from “short” to “long” foundations). Usability of the proposed analytical model in engineering practice is proved by numerical simulations; the obtained results are on the safe side with quite acceptable margin of additional safety.

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