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1
Yamaoka, Seiji. "Minimum-Time Guidance and Control Law for High Maneuvering Missile". International Journal of Aeronautical and Space Sciences 10, nr 1 (30.05.2009): 46–58. http://dx.doi.org/10.5139/ijass.2009.10.1.046.
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UENO, Seiya. "Minimum-Time Turns of Aircraft by Feedback Guidance and Control Law." Journal of the Japan Society for Aeronautical and Space Sciences 45, nr 516 (1997): 29–35. http://dx.doi.org/10.2322/jjsass1969.45.29.
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Indig, Nahshon, Joseph Z. Ben-Asher i Erez Sigal. "Near-Optimal Minimum-Time Guidance Under Spatial Angular Constraint in Atmospheric Flight". Journal of Guidance, Control, and Dynamics 39, nr 7 (lipiec 2016): 1563–77. http://dx.doi.org/10.2514/1.g001485.
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Ariba, Yassine, Denis Arzelier i Laura Sofia Urbina-Iglesias. "Minimum-Fuel Fixed-Time Impulsive Elliptic Glide-Slope Guidance Algorithms Using Semidefinite Programming". Journal of Guidance, Control, and Dynamics 41, nr 9 (wrzesień 2018): 1873–87. http://dx.doi.org/10.2514/1.g003395.
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Alamir, Mazen. "Nonlinear receding horizon sub-optimal guidance law for the minimum interception time problem". Control Engineering Practice 9, nr 1 (styczeń 2001): 107–16. http://dx.doi.org/10.1016/s0967-0661(00)00085-x.
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Zhou, Guanqun, i Qunli Xia. "A Guidance Strategy for Strapdown Seeker considering Minimum Field-of-View Angle Constraint". International Journal of Aerospace Engineering 2020 (19.06.2020): 1–11. http://dx.doi.org/10.1155/2020/5247257.
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An off-axis strapdown seeker in missile may lead to a minimum field-of-view (FOV) angle constraint problem. The goal of this paper is to deal with the problem in guidance. Analysis of kinematics proves that on the premise of attacking stationary target, seeker look angle comes to 0 before or at the end time, and seeker will lose target finally. In order to reduce the distance of seeker losing target, a guidance strategy is proposed to sustain minimum FOV angle constraint during flight. The strategy can be applied on guidance laws with independent orders in longitudinal and lateral channels. By means of a certain rolling maneuver, it keeps the target in the seeker’s limited FOV. Moreover, a lateral guidance order compensation is utilized in the strategy to maintain seeker look angle. Simulations and comparisons are conducted to demonstrate the strategy’s effectiveness. Results show that the guidance strategy can sustain minimum FOV angle constraint longer than classical guidance method.
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Wu, Zhenglong, Zhenyu Guan, Chengwei Yang i Jie Li. "Terminal Guidance Law for UAV Based on Receding Horizon Control Strategy". Complexity 2017 (2017): 1–19. http://dx.doi.org/10.1155/2017/2750172.
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Terminal guidance law against the maneuvering target is always the focal point. Most of the literatures focus on estimating the acceleration of target and time to go in guidance law, which are difficult to acquire. This paper presents a terminal guidance law based on receding horizon control strategy. The proposed guidance law adopts the basic framework of receding horizon control, and the guidance process is divided into several finite time horizons. Then, optimal control theory and target motion prediction model are used to derive guidance law for minimum time index function with continuous renewal of original conditions at the initial time of each horizon. Finally, guidance law performs repeated iteration until intercepting the target. The guidance law is of subprime optimal type, requiring less guidance information, and does not need to estimate the acceleration of target and time to go. Numerical simulation has verified that the proposed guidance law is more effective than traditional methods on constant and sinusoidal target with bounded acceleration.
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Ariba, Yassine, Denis Arzelier i Laura Sofia Urbina. "A New Glideslope Guidance Algorithm for Minimum-Fuel Fixed-Time Elliptic Rendezvous Using Semidefinite Programming". IFAC-PapersOnLine 50, nr 1 (lipiec 2017): 7235–40. http://dx.doi.org/10.1016/j.ifacol.2017.08.1369.
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Kim, Kangsoo, i Tamaki Ura. "Applied Model-Based Analysis and Synthesis for the Dynamics, Guidance, and Control of an Autonomous Undersea Vehicle". Mathematical Problems in Engineering 2010 (2010): 1–23. http://dx.doi.org/10.1155/2010/149385.
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Model-based analysis and synthesis applied to the dynamics, guidance, and control of an autonomous undersea vehicle are presented. As the dynamic model for describing vehicle motion mathematically, the equations of motion are derived. The stability derivatives in the equations of motion are determined by a simulation-based technique using computational fluid dynamics analysis. The dynamic model is applied to the design of the low-level control systems, offering model-based synthetic approach in dynamics and control applications. As an intelligent navigational strategy for undersea vehicles, we present the optimal guidance in environmental disturbances. The optimal guidance aims at the minimum-time transit of a vehicle in an environmental flow disturbance. In this paper, a newly developed algorithm for obtaining the numerical solution of the optimal guidance law is presented. The algorithm is a globally working procedure deriving the optimal guidance in any deterministic environmental disturbance. As a fail-safe tactic in achieving the optimal navigation in environments of moderate uncertainty, we propose the quasi-optimal guidance. Performances of the optimal and the quasi-optimal guidances are demonstrated by the simulated navigations in a few environmental disturbances.
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Li, Bin, Defu Lin, Jiang Wang i Song Tian. "Guidance law to control impact angle and time based on optimality of error dynamics". Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, nr 10 (24.09.2018): 3577–88. http://dx.doi.org/10.1177/0954410018801226.
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In this work, a new guidance law with a meaningful performance index is designed to satisfy terminal impact angle and impact time constraints based on optimal error dynamics, which can be used for salvo attacks or cooperative missions of multi-missile. The analytical solution of the proposed guidance law is a combination of trajectory shaping guidance law and an additional impact time error feedback term that is proportional to the difference between the desired and the true impact times. Trajectory shaping guidance law aims to achieve the desired terminal impact angle and zero miss distance, whereas the extra term aims to meet the desired impact time. The minimum and maximum feasible impact times that consider the seeker's field-of-view limit, terminal impact angle constraint, and missile's maneuvering acceleration limit are calculated to provide the feasible boundary range of the desired impact time. Numerical simulations of several engagement situations demonstrate the effectiveness of the proposed guidance law in the accuracy of terminal impact angle and impact time.
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Fu, Lei, Min Xu, Xiao Min An i Xun Liang Yan. "Design and Optimization of Low-Thrust Orbit Transfers Using Hybrid Method". Advanced Materials Research 588-589 (listopad 2012): 335–39. http://dx.doi.org/10.4028/www.scientific.net/amr.588-589.335.
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A low-thrust guidance scheme, which is weighted combined by taking the optimum strategy of thrust allocation and the target deficits value into consideration for each orbital element, is developed. The presented guidance scheme is predictive in nature and does not rely on a stored reference trajectory or reference controls. The orbit transfer problem is converted into parametric optimization and utilizing a hybrid genetic algorithm. The minimum-time orbit transfer is considered. The influence of the Earth’s oblateness is taken into consideration in the simulation of minimum-time. A conclusion is drawn that the designed method presented here turns out to be an autonomous scheme because the information of target orbit is considered in the transfer process.
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Du, Wenhao, Wanchun Chen, Liang Yang i Hao Zhou. "Optimal Midcourse Guidance Algorithm for Exoatmospheric Interception Using Analytical Gradients". International Journal of Aerospace Engineering 2019 (16.09.2019): 1–17. http://dx.doi.org/10.1155/2019/8502870.
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This paper is aimed at providing a semianalytical method to solve the optimal exoatmospheric interception problem with the minimum fuel consumption. A nonlinear programming (NLP) problem with the minimum velocity increment, which involves Lambert’s problem with unspecified time-of-flight, is firstly formulated. Then, a set of Karush-Kuhn-Tucker conditions and the Jacobian matrix corresponding to those conditions are derived in an analytical manner, even though the derivatives are mathematically complicated and computationally onerous. Therefore, the Newton-Raphson method can be used to efficiently solve this problem. To further decrease computational cost, a near-optimal initialization method reducing the dimension of the search space is presented to provide a better initial guess. The performance of the proposed method is assessed by numerical experiments and comparison with other methods. The results show that this method is not only of high computational efficiency and accuracy but also applicable to onboard guidance.
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Mu, Dongdong, Guofeng Wang, Yunsheng Fan, Yiming Bai i Yongsheng Zhao. "Fuzzy-Based Optimal Adaptive Line-of-Sight Path Following for Underactuated Unmanned Surface Vehicle with Uncertainties and Time-Varying Disturbances". Mathematical Problems in Engineering 2018 (2018): 1–12. http://dx.doi.org/10.1155/2018/7512606.
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This paper investigates the path following control problem for an underactuated unmanned surface vehicle (USV) in the presence of dynamical uncertainties and time-varying external disturbances. Based on fuzzy optimization algorithm, an improved adaptive line-of-sight (ALOS) guidance law is proposed, which is suitable for straight-line and curve paths. On the basis of guidance information provided by LOS, a three-degree-of-freedom (DOF) dynamic model of an underactuated USV has been used to design a practical path following controller. The controller is designed by combining backstepping method, neural shunting model, neural network minimum parameter learning method, and Nussbaum function. Neural shunting model is used to solve the problem of “explosion of complexity,” which is an inherent illness of backstepping algorithm. Meanwhile, a simpler neural network minimum parameter learning method than multilayer neural network is employed to identify the uncertainties and time-varying external disturbances. In particular, Nussbaum function is introduced into the controller design to solve the problem of unknown control gain coefficient. And much effort is made to obtain the stability for the closed-loop control system, using the Lyapunov stability theory. Simulation experiments demonstrate the effectiveness and reliability of the improved LOS guidance algorithm and the path following controller.
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Kumar, G. Naresh, AK Sarkar i SE Talole. "Dynamic pressure based mid-course guidance scheme for hypersonic boost-glide vehicle". Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, nr 9 (24.08.2018): 3211–22. http://dx.doi.org/10.1177/0954410018795265.
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In this study, a guidance scheme for an aerodynamically controlled hypersonic boost-glide class of flight vehicle is proposed. In this work, optimum glide dynamic pressure corresponding to maximum L/ D throughout the flight is calculated and a mid-course guidance law formulation to track the dynamic pressure while suppressing phugoid oscillations is proposed for real-time flight trajectory shaping. Efficacy of the proposed guidance scheme has been demonstrated through simulation studies. Robustness analysis on the proposed guidance algorithm is carried out using Monte Carlo technique. Lastly, a pattern search algorithm-based offline generated maximum L/ D optimal trajectory existing in literature, which meets minimum dynamic pressure, maximum airframe skin temperature, as well as other in-flight and terminal constraints is used as reference trajectory to evaluate the performance of the proposed guidance scheme.
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Sang, D.-K., i M.-J. Tahk. "Guidance law switching logic considering the seeker's field-of-view limits". Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 223, nr 8 (1.08.2009): 1049–58. http://dx.doi.org/10.1243/09544100jaero614.
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The impact time control guidance (ITCG) method, which has been proposed recently, can be applied successfully to a salvo attack of multiple missiles. Compared to the proportional navigation guidance law, this guidance method makes additional manoeuvres to synchronize the impact times. However, such manoeuvres do not consider the manoeuvrability and the seeker's field-of-view (FOV) of a missile and may cause the target to move out of the missile seeker's FOV; maintaining the seeker lock-on condition during the engagement is critical for missile guidance. To solve this problem, two methods are presented in this article: one is based on the calculation of minimum and maximum flight times considering the missile's manoeuvring limit and the seeker's FOV limit to check the available impact time. The other is based on guidance law switching logic that keeps the target look angle of the seeker constant. These methods can provide the boundary limit of the impact time of the salvo attack and prevent the lock-on failure because of the seeker's FOV limit of the missile during the homing phase when the ITCG is used. This method was applied to the case of a time critical salvo-attack of multiple missiles, which have manoeuvring limit and the seeker's FOV limit, and desired results were obtained.
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Wang, Xin, i Xue Qiu. "Study on Fuzzy Neural Sliding Mode Guidance Law with Terminal Angle Constraint for Maneuvering Target". Mathematical Problems in Engineering 2020 (24.08.2020): 1–12. http://dx.doi.org/10.1155/2020/4597937.
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Aiming at the requirement that the guidance law should meet the minimum miss distance and the desired terminal angle at the same time, a sliding mode variable structure control method is introduced. In order to improve the fuzzy variable structure guidance law for maneuvering target attack effect, a neural network to the optimization design is carried out on the guidance law. The neural network is trained by the samples, which is under the condition of different error coefficient of angle, the coefficient of reaching law, and the coefficient of on-off item about target. Fuzzy neural sliding mode guidance law with terminal angle constraint can increase the performance of the large maneuvering target. In addition, on the basis of the traditional PC platform visual simulation system, a new guidance law simulation platform based on embedded system and virtual reality technology is formed. The platform can verify the validity of the guidance law.
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Sun, Zuwen, i Natalie Baddour. "On the Time Frequency Compactness of the Slepian Basis of Order Zero for Engineering Applications". Computation 11, nr 6 (13.06.2023): 116. http://dx.doi.org/10.3390/computation11060116.
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Time and frequency concentrations of waveforms are often of interest in engineering applications. The Slepian basis of order zero is an index-limited (finite) vector that is known to be optimally concentrated in the frequency domain. This paper proposes a method of mapping the index-limited Slepian basis to a discrete-time vector, hence obtaining a time-limited, discrete-time Slepian basis that is optimally concentrated in frequency. The main result of this note is to demonstrate that the (discrete-time) Slepian basis achieves minimum time-bandwidth compactness under certain conditions. We distinguish between the characteristic (effective) time/bandwidth of the Slepians and their defining time/bandwidth (the time and bandwidth parameters used to generate the Slepian basis). Using two different definitions of effective time and bandwidth of a signal, we show that when the defining time-bandwidth product of the Slepian basis increases, its effective time-bandwidth product tends to a minimum value. This implies that not only are the zeroth order Slepian bases known to be optimally time-limited and band-concentrated basis vectors, but also as their defining time-bandwidth products increase, their effective time-bandwidth properties approach the known minimum compactness allowed by the uncertainty principle. Conclusions are also drawn about the smallest defining time-bandwidth parameters to reach the minimum possible compactness. These conclusions give guidance for applications where the time-bandwidth product is free to be selected and hence may be selected to achieve minimum compactness.
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Chen, Zhigang, Ying Wang, Mingwei Sun, Zenghui Wang i Zengqiang Chen. "Practical Energy Dissipation Control of Near Space Glider on Independent Longitudinal Plane". International Journal of Aerospace Engineering 2020 (21.11.2020): 1–22. http://dx.doi.org/10.1155/2020/8854837.
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The near-space hypersonic aerodynamic glider has strong maneuverability in wide flight envelope. The glide is generally achieved in a smooth manner with no or weak altitude oscillations in the altitude. The maximum lift-to-drag ratio glide is a typical trajectory that can approximate the maximum glide range, which is a crucial indicator for a glider. However, another important indicator, the minimum glide range, which is used in some time-sensitive missions and is expected to reduce the velocity to a specified threshold in a short longitudinal range, is difficult to be realized. In practice, the excessive velocity or energy is usually dissipated during lateral manipulation, wherein either the entire glide range or the glide time is not shortened. An innovative guidance strategy is proposed for achieving the minimum glide range based on a typical maximum glide scheme and bang-bang control scheme only on the longitudinal plane, and the flight time can be reduced considerably. Then, a practical extended state observer based pitch control is utilized to efficiently track the bang-bang command within a wide velocity envelope to achieve the guidance objective. Extensive simulation results demonstrate the effectiveness of the proposed methods.
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Samani, Mohammad, Mona Tafreshi, Iman Shafieenejad i Amir Ali Nikkhah. "Minimum-time open-loop and closed-loop optimal guidance with GA-PSO and neural fuzzy for Samarai MAV flight". IEEE Aerospace and Electronic Systems Magazine 30, nr 5 (maj 2015): 28–37. http://dx.doi.org/10.1109/maes.2015.7119822.
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Zuo, Xiaolong, Jun Bi, Yongxing Wang i Yujia Du. "A Charging Guidance Optimization Model for Electric Vehicle Travel by Considering Multi-Dimensional Preferences of Users". World Electric Vehicle Journal 14, nr 7 (27.06.2023): 171. http://dx.doi.org/10.3390/wevj14070171.
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The dual-carbon strategy advocates a green, environmentally friendly, and low-carbon lifestyle. In the field of transportation, electric vehicles (EVs) have been regarded as an effective solution to reduce carbon emissions and to conserve energy. Developing a reasonable charging guidance scheme for users is a feasible way to solve problems, such as the range anxiety of EV users, and has a great application value for the promotion of EVs in the future. In practical situations, how to develop charging induction schemes for users that better meet their needs according to the type of user and their multi-dimensional preferences is the focus of this paper. To this end, this study utilized charging behavioral data to investigate the multi-dimensional charging preference of users based on the collaborative filtering algorithm. Then, a multi-objective optimization model was established based on the preference degree of each charging station and the integrated travel cost. An NSGA-III framework was used to design the algorithm to solve the proposed model. The algorithm was tested using simulation experiments that were designed based on the road network and charging stations in Beijing. The final result is an experimental analysis of the weight matrices for the three different preferences of minimum energy consumption cost, minimum time cost, and minimum fee cost, which yields a difference of about 4.4% between the optimal energy consumption cost and the maximum energy cost, about 2.9% between the optimal time cost and the maximum time cost, and about 10% between the optimal fee cost and the maximum fee cost under these three different preferences, respectively. The proposed multi-objective optimization model is able to provide users with reliable charging station selection by incorporating their personalized charging preference characteristics and charge guidance schemes.
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Galel, Z., J. L. Hunt i T. H. Unger. "Laser Guidance for Repairing Gas Turbine Parts". Journal of Engineering for Gas Turbines and Power 117, nr 3 (1.07.1995): 540–44. http://dx.doi.org/10.1115/1.2814128.
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As a result of normal operating conditions, jet engine parts tend to distort. During repair, many of these parts require some form of selective cutting. Due to the differences between each individual part, automation such as CNC machining becomes complex. The need to map each individual part prior to machining has prohibited repair facilities from introducing sophisticated automation. This paper presents for the first time a novel method that addresses many problems related to selective material removal in jet engine repairs. Similar to a terrain-following cruise missile, a laser-guided cutter is used to follow a selected datum surface. For example, in the case of Honeycomb Airseals, the thin laser beam penetrates the honeycomb cell structure to follow the base metal. The method minimizes parent metal removal and under-minimum-wall condition. As a result, life potential of parts is extended, and repair costs are reduced. The ability to track a moving part and modify the cutting path automatically produces one more significant advantage: Accurate setup of a part on a machine is no longer critical. The method has applications in the repair of airseals, frames and cases, and airfoils.
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Fox, Garey A., Lucie Guertault, Celso Castro-Bolinaga i Alexis Swanson. "Guidance on Applied Pressure Heads for Quantifying Cohesive Soil Erodibility with a Jet Erosion Test (JET)". Journal of the ASABE 65, nr 6 (2022): 1443–50. http://dx.doi.org/10.13031/ja.14884.
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Highlights Jet erosion test (JET) is a commonly used instrument for quantifying soil erodibility. Uncertainty remains on an appropriate applied pressure head to ensure high-quality JET data. Numerical analysis was used to derive minimum and maximum heads for four soil classifications. Ideal applied pressure heads depend on soil erodibility parameters and user-selected JET characteristics. Abstract. The Jet Erosion Test (JET) is one of the few instruments available for measuring cohesive soil erodibility in situ, but uncertainty remains regarding an appropriate initial applied pressure head for the test. Users typically iterate on an initial applied pressure head setting when testing soil. This iteration is necessary to ensure a reasonable erosion rate and the total amount of scour while imposing applied shear stresses that match the expected application range when using JET-derived erodibility parameters. This research used a numerical analysis of simulated JETs to determine both minimum and maximum applied pressure heads, ensuring a logistically appropriate estimation of soil erodibility parameters. First, the minimum head was set to generate at least 25 mm of scour, established based on data from previous in situ JETs. Second, the maximum applied pressure head was set to ensure that no excessively large initial applied shear stress impacted the estimation of erodibility parameters from a linear regression on erosion rates. Analyses were conducted for four selected soil erodibility classes: highly erodible, more erodible, erodible, and moderately resistant soils. Curves showing the ideal applied pressure ranges were generated for initial time intervals of scour depth measurements of 60, 90, 120, 180, 240, and 360 s and dimensionless initial nozzle heights of 1.00, 1.25, and 1.50. The appropriate range in the applied pressure head depended not only on the soil erodibility classes but also on the initial time interval for scour depth measurements, total test duration, and dimensionless initial nozzle height above the soil surface. Users should ensure that a minimum applied pressure head is exceeded for resistant soils. Maximum applied pressure heads should be considered for erodible, more erodible, and highly erodible soils, dependent on the initial time interval for scour depth measurements and dimensionless initial nozzle heights. Wider ranges of acceptable applied pressure heads were observed with smaller initial time intervals. The procedure presented in this research can be readily adapted by JET users to reflect specific testing conditions (e.g., different data collection intervals and test durations) for ensuring the a priori use of effective pressure head settings. Keywords: Cohesive soils, Erodibility, Jet erosion test, Pressure head, Soil erodibility.
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Liu, Jing, Pengqiang Zheng, Yubao Zhan, Zhiguo Li i Zhaoxia Shi. "Urban Regional Building Energy Planning Model under the Guidance of Network Flow Theory". Processes 11, nr 1 (21.12.2022): 8. http://dx.doi.org/10.3390/pr11010008.
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The satisfactory construction of regional building energy planning models is a key technology in effective energy allocation. At present, the selection of energy planning is only based on artificial judgment criteria, which leads to a high subjectivity in energy planning. This research innovatively introduces the network flow theory into the urban regional building energy planning model. Combined with the actual characteristics of regional building energy planning, the regional building energy planning model was constructed and the regional energy distribution mode was optimized. The model includes the energy supply layer, energy conversion layer, and energy demand layer. At the same time, the minimum cost and maximum flow problem of the model was solved with the help of the BG iterative algorithm. The model includes the energy supply layer, energy conversion layer, and energy demand layer. We used the BG iterative algorithm to solve the minimum cost and maximum flow problem of the model. The accuracy, accuracy, recall rate, and specificity of the four minimum cost maximum flows tended to be stable with the increase of the number of iterations. After the application of BG iterative algorithm, the cost consumption of each part of the regional building energy planning model in summer will be significantly reduced, and the total consumption cost is 929 million dollars. The research results verify the high applicability of introducing the network flow theory and BG iterative algorithm to construct and solve the regional building energy planning model, which can be applied to the rational allocation of resources in the region.
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Antoniadis, I. "Guidance Preconditioning by an Impulse Sequence for Robust Residual Vibration Suppression". Shock and Vibration 6, nr 3 (1999): 133–45. http://dx.doi.org/10.1155/1999/250173.
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In order to suppress residual vibrations, a general method is presented for preconditioning any guidance function prior to its application to a dynamic system, by convolving it with a sequence of impulses. The approach includes first the development of the necessary design specifications for the impulse sequence, so that the robustness properties cover the widest possible variation of the system natural frequencies. Three solution methods are proposed then, with special emphasis in the achievement of the minimum possible duration time of the impulse sequence. Numerical experiments verify the effectiveness of the robustness, not only with respect to variations of the natural frequency, but also with respect to variations of a range of other linear and non-linear variables.
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Williams, Edwin, i Yan Jin. "Dynamic Probability Fields for Risk Assessment and Guidance Solutions". Annual of Navigation 26, nr 1 (1.12.2019): 33–45. http://dx.doi.org/10.1515/aon-2019-0004.
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Abstract Standard Guidance, Navigation, and Control (GN&C) systems take state data from a navigation system and create a trajectory that minimizes some a-priori determined cost function. These cost functions are typically time, money, weight, or any general physically realizable quantity. Previous work has been done to show the effectiveness of using risk as the sole objective function. However, this previous work used Poisson distributions and historical estimates to achieve this goal. In this paper we present the situation-risk assessment (SRA) method contained within the intelligent situation assessment and collision avoidance (iSC) platform. The SRA method uses data clustering, and pattern recognition to create a historically based estimate of guidance probabilities. These are then used in data driven, dynamic models to create the future probability fields of the situation. This probability, along with the other agent’s goals and objectives, are then used to create a minimum risk guidance solution in the nautical environment.
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FUKUMOTO, Hiroshi, i Seiya UENO. "A Method of Minimum-Time Formation Guidance Based on Optimal Solutions of Single Fixed-Wing Aircraft by using Homotopy Method". AEROSPACE TECHNOLOGY JAPAN, THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES 16 (2017): 109–14. http://dx.doi.org/10.2322/astj.jsass-d-17-00046.
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WAH, BENJAMIN W., i MINGLUN QIAN. "VIOLATION-GUIDED NEURAL-NETWORK LEARNING FOR CONSTRAINED FORMULATIONS IN TIME-SERIES PREDICTIONS". International Journal of Computational Intelligence and Applications 01, nr 04 (grudzień 2001): 383–97. http://dx.doi.org/10.1142/s1469026801000317.
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Time-series predictions by artificial neural networks (ANNs) are traditionally formulated as unconstrained optimization problems. As an unconstrained formulation provides little guidance on search directions when a search gets stuck in a poor local minimum, we have proposed to use a constrained formulation in order to use constraint violations to provide additional guidance. In this paper, we formulate ANN learning with cross-validations for time-series predictions as a non-differentiable nonlinear constrained optimization problem. Based on our theory of Lagrange multipliers for discrete constrained optimization, we propose an efficient learning algorithm, called violation guided back-propagation (VGBP), that computes an approximate gradient using back-propagation (BP), that introduces annealing to avoid blind acceptance of trial points, and that applies a relax-and-tighten (R&T) strategy to achieve faster convergence. Extensive experimental results on well-known benchmarks, when compared to previous work, show one to two orders-of-magnitude improvement in prediction quality, while using less weights.
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BHOWMIK, S. K. ROY, SANKAR NATH, A. K. MITRA i H. R. HATWAR. "Application of Neural Network Technique to improve the location specific forecast of temperature over Delhi from MM5 model". MAUSAM 60, nr 1 (27.11.2021): 11–24. http://dx.doi.org/10.54302/mausam.v60i1.958.
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India Meteorological Department (IMD) has been using direct model output (2 meters height temperature) of MM5 model as numerical guidance for forecasting maximum and minimum temperature of Delhi in short range time scale (up to 72 hours). Performance statistics of the direct model outputs of the model for maximum and minimum temperature show that forecast skill of the model is reasonably good, particularly for the minimum temperature. For further improving the model forecast, Neural Network (NN) as well as regression techniques are applied so that the systematic errors of the direct model output of the model for maximum and minimum temperature could be reduced. The study shows that both Neural Network approach and regression technique are capable to improve the forecast skill of maximum and minimum temperature. Daily modified forecasts are found persistently closer to the observations when the method is tested with the independent sample. The methods are found to be promising for operational application.
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Miao, Xinyuan, Lin Cheng, Yu Song, Junfeng Li i Shengping Gong. "Semi-Analytical Planetary Landing Guidance with Constraint Equations Using Model Predictive Control". Applied Sciences 12, nr 12 (17.06.2022): 6166. http://dx.doi.org/10.3390/app12126166.
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With the deepening of planetary exploration, rapid decision making and descent trajectory planning capabilities are needed to cope with uncertain environmental disturbances and possible faults during planetary landings. In this article, a novel decoupling method is adopted, and the analytical three-dimensional constraint equations are derived and solved, ensuring real-time guidance computation. The three-dimensional motion modes and thrust profiles are analyzed and determined based on Pontryagin’s minimum principle, and a supporting semi-analytical reachability judgment method is presented, which can also be used to determine controllability. The algorithm is embedded in the model predictive control (MPC) framework, and several techniques are adopted to enhance stability and robustness, including thrust averaging, thrust correction after ignition, thrust reservation, and open-loop terminal guidance. Numerical simulations demonstrate that the proposed algorithm can guarantee real-time trajectory generation and meanwhile maintain considerable optimality. In addition, the MPC simulation shows that the algorithm can maintain a good accuracy under external disturbances.
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Wu, Jianhui, Yuanfa Ji, Xiyan Sun i Yan Xu. "Guidance Optimization of Travelers’ Travel Mode Choice Based on Fuel Tax Rate and Bus Departure Quantity in Two-Mode Transportation System". Journal of Advanced Transportation 2020 (12.01.2020): 1–10. http://dx.doi.org/10.1155/2020/4190632.
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This aim of this study is to improve the guidance role of the fuel tax rate and bus departure quantity on travel mode choice. Car and bus travel are chosen as the research object, and a day-to-day evolution model of dual-mode network traffic flow (based on a stochastic user equilibrium model and the method of network tatonnement process) is established. Subsequently, a guidance optimization model of fuel tax rate and bus departure quantity is designed. This guidance optimization model is formulated to determine the comprehensive minimum value among system total travel time of car travel, system total comprehensive cost of bus travel, and the difference between the total operating cost of bus departure increment and the total amount of fuel tax levied on car travelers. Through numerical examples, the validity of this guidance optimization model is verified, and the influence of fuel tax rate and bus departure quantity on the traffic network is analyzed. The results show that a guidance optimization scheme based on fuel tax rate and bus departure quantity can help regulate the proportion of car travel and improve bus service quality.
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Ren, Chuanxiang, Li Wang, Changchang Yin, Zhen Wang, Xuehai Chen i Juntao Li. "Research on the Platoon Speed Guidance Strategy at Signalized Intersections in the Connected Vehicle Environment". Journal of Advanced Transportation 2023 (6.06.2023): 1–25. http://dx.doi.org/10.1155/2023/9984537.
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The development of connected vehicle (CV) technology has created conditions for improving the traffic efficiency of intersections and provided support for more effective speed guidance at signalized intersections. First, this paper proposes a platoon speed guidance strategy to reduce the fuel consumption and delay of the platoon passing through the intersection and smooth traffic oscillation, which includes constant speed guidance, deceleration guidance, acceleration guidance, and stop guidance. Then, the optimal speed calculation method is designed, including the calculation of the platoon’s passable period and maximum number of passing vehicles, the platoon restructure method, the analysis of the trajectory of the vehicles, and the calculation of the optimal trajectory of the platoon based on the goal of minimum fuel consumption and delay. Finally, eight different intersection scenarios are designed to simulate the proposed platoon speed guidance strategy. The results show that the platoon speed guidance strategy can effectively reduce the fuel consumption and delay of the platoon passing through the intersection and smooth traffic oscillation. In addition, the influences of queue length and CV penetration rate on the platoon speed guidance strategy are also discussed. The results show that when the queue length affects the passable period, the improvement in fuel consumption, drive time, and delay will decrease as the queue length increases. And as the penetration rate increases, the strategy becomes increasingly effective in reducing the delay and fuel consumption of the platoon in general.
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Kumar, G. N., i A. K. Sarkar. "CMAC Trained Optimum Mid course Guidance for Tactical Flight Vehicle". Defence Science Journal 71, nr 6 (22.10.2021): 826–35. http://dx.doi.org/10.14429/dsj.71.16295.
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This paper discusses design and validation of neural network based mid-course guidance law of a surface to air flight vehicle. In present study, initially different optimal trajectories have been generated off-line of different pursuer-evader engagements by ensuring minimum flight time, maximum terminal velocity and favorable handing over conditions for seeker based terminal guidance. These optimal trajectories have been evolved by nonlinear programming based direct method of optimisation. The kinematic information of both pursuer and evader, generated based on these trajectories have been used to train cerebellar model articulate controller (CMAC) neural network. Later for a given engagement scenario an on-line near optimal mid-course guidance law has been evolved based on output of trained network. Training has been carried out by CMAC type supervisory neural network. The tested engagement condition is within input/output training space of neural network. Seeker based homing guidance has been used for terminal phase. Complete methodology has been validated along pitch plane of pursuer-evader engagement. During mid-course phase, the guidance demand has been tracked by attitude hold autopilot and during terminal phase, the guidance demanded lateral acceleration has been tracked by acceleration autopilot. System robustness has been studied in presence of plant parameter variations and sensor noise under Monte Carlo Platform.
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Roshanian, J., M. Zareh, H. H. Afshari i M. Rezaei. "An L1 adaptive closed-loop guidance law for an orbital injection problem". Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering 223, nr 6 (6.07.2009): 753–61. http://dx.doi.org/10.1243/09596518jsce789.
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The current paper presents the determination of a closed-loop guidance law for an orbital injection problem using two different approaches and, considering the existing time-optimal open-loop trajectory as the nominal solution, compares the advantages of the two proposed strategies. In the first method, named neighbouring optimal control (NOC), the perturbation feedback method is utilized to determine the closed-loop trajectory in an analytical form for the non-linear system. This law, which produces feedback gains, is in general a function of small perturbations appearing in the states and constraints separately. The second method uses an L1 adaptive strategy in determination of the non-linear closed-loop guidance law. The main advantages of this method include characteristics such as improvement of asymptotic tracking, guaranteed time-delay margin, and smooth control input. The accuracy of the two methods is compared by introducing a high-frequency sinusoidal noise. The simulation results indicate that the L1 adaptive strategy has a better performance than the NOC method to track the nominal trajectory when the noise amplitude is increased. On the other hand, the main advantage of the NOC method is its ability to solve a non-linear, two-point, boundary-value problem in the minimum time.
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Singh, Netra, i Manoranjan Sinha. "Suboptimal Guidance and Control Design for a Missile with Onboard Strapdown Seeker". Applied Mechanics and Materials 110-116 (październik 2011): 2513–20. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.2513.
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Dynamic inversion control in conjunction with nonlinear suboptimal three dimensional (3-D) guidance law, in terminal phase, is implemented in both the pitch and yaw plane for a short range surface to surface missile with onboard active strapdown seeker. The implemented guidance and control laws intercept the target with a minimum miss distance in addition to meeting the various constraints such as line of sight, seeker field-of-view (FOV), and impact angle. This is achieved using approximate solution to Hamilton-Jacobi-Bellman (HJB) equation [1]. Dynamic inversion control is implemented in two time scales for the inner loop body rate and outer loop angles. Various nonlinearities including that due to the coupling effect between pitch and yaw channels are accounted for in the six-degree-of-freedom (6-DOF) formulation.
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Al Taqatqa, Firas Ahmad Saleem. "Adopting and Establishing Gifted Children Counselling and Guidance Programs". International Journal of Social Science Research and Review 5, nr 10 (27.10.2022): 472–80. http://dx.doi.org/10.47814/ijssrr.v5i10.685.
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The study's overarching goals are to determine the nature of the skills taught in schools, the characteristics of the students who excel under those circumstances, the nature of the services available to gifted children, and the nature of the factors that either stifle or foster the development of students' talents. Quantitative study would not be complete without this aspect. Data is collected through in-person interviews, on-the-job observations, and detailed notes. The method utilized to analyse the data also meets the criteria set out by Miles and Huberman. The findings indicate that gifted children are those who excel in areas where their peers often struggle, who show exceptional skill in select areas, and who reach the greatest levels of accomplishment in those areas. Throughout the course of a typical counselling session, a minimum of five of the seven theoretical components of guidance and counselling will be used. The distinctiveness of the student, the encouragement of teachers and peers, the student's personal interests and drive, the resources available at the madrasa, and the community all play a role in offering aid. Constraints of time, location, and the availability of all required resources, as well as the impression of counselling and guidance instructors' lack of attention, all operate against pupils.
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Wang, Lianzhen, Han Zhang, Lingyun Shi, Qingling He i Huizhi Xu. "Optimization Model of Regional Traffic Signs for Inducement at Road Works". Sustainability 13, nr 13 (22.06.2021): 6996. http://dx.doi.org/10.3390/su13136996.
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A variety of pipelines are distributed under urban roads. The upgrading of pipelines is bound to occupy certain road resources, compress the driving space of motor vehicles for a long time, aggravate the traffic congestion in the construction section, and then affect the traffic operation of the whole region. A reasonable layout of traffic signs for inducement to guide the traffic flow in the area where the construction section is located is conducive to promoting a balanced distribution of traffic flow in the regional road network, so as to achieve the reduction of automobile exhaust emissions and the sustainable development of traffic. In this paper, the layout optimization method of regional traffic signs for inducement is proposed. Taking the maximum amount of guidance information that the regional traffic signs can provide as the objective function, and taking the traffic volume, the characteristics of intersection nodes and the standard deviation of road saturation as the independent variables, the layout optimization model of guidance facilities is constructed, which can optimize the layout of traffic guidance signs in the area affected by the construction section, and achieve the goal that the minimum number of facilities can provide the maximum amount of guidance information. The results of the case study show that among the 64 alternative locations where traffic guidance signs can be set in the study area, eight optimal locations are finally determined as the setting points of guidance facilities through this model, and the effective increment of guidance information is the largest at this time. The model proposed in this paper can be used for reference to promote the sustainable development of traffic in the area where the construction section is located.
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Wan, Shizheng, Xiaofei Chang, Quancheng Li i Jie Yan. "Finite-Horizon Optimal Tracking Guidance for Aircraft Based on Approximate Dynamic Programming". Mathematical Problems in Engineering 2019 (21.03.2019): 1–12. http://dx.doi.org/10.1155/2019/8649781.
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Referring to the optimal tracking guidance of aircraft, the conventional time based kinematics model is transformed into a downrange based model by independent variable replacement. The deviations of in-flight altitude and flight path angle are penalized and corrected to achieve high precision tracking of reference trajectory. The tracking problem is solved as a linear quadratic regulator applying small perturbation theory, and the approximate dynamic programming method is used to cope with the solving of finite-horizon optimization. An actor-critic structure is established to approximate the optimal tracking controller and minimum cost function. The least squares method and Adam optimization algorithm are adopted to learn the parameters of critic network and actor network, respectively. A boosting trajectory with maximum final velocity is generated by Gauss pseudospectral method for the validation of guidance strategy. The results show that the trained feedback control parameters can effectively resist random wind disturbance, correct the initial altitude and flight path angle deviations, and achieve the goal of following a given trajectory.
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Behr, Madeline R., Shams K. Halat, Andrew B. Sholl, Louis Spencer Krane i Jonathan Quincy Brown. "Rapid On-Site Microscopy and Mapping of Diagnostic Biopsies for See-And-Treat Guidance of Localized Prostate Cancer Therapy". Cancers 15, nr 3 (27.01.2023): 792. http://dx.doi.org/10.3390/cancers15030792.
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Prostate cancer continues to be the most diagnosed non-skin malignancy in men. While up to one in eight men will be diagnosed in their lifetimes, most diagnoses are not fatal. Better lesion location accuracy combined with emerging localized treatment methods are increasingly being utilized as a treatment option to preserve healthy function in eligible patients. In locating lesions which are generally <2cc within a prostate (average size 45cc), small variance in MRI-determined boundaries, tumoral heterogeneity, patient characteristics including location of lesion and prostatic calcifications, and patient motion during the procedure can inhibit accurate sampling for diagnosis. The locations of biopsies are recorded and are then fully processed by histology and diagnosed via pathology, often days to weeks later. Utilization of real-time feedback could improve accuracy, potentially prevent repeat procedures, and allow patients to undergo treatment of clinically localized disease at earlier stages. Unfortunately, there is currently no reliable real-time feedback process for confirming diagnosis of biopsy samples. We examined the feasibility of implementing structured illumination microscopy (SIM) as a method for on-site diagnostic biopsy imaging to potentially combine the diagnostic and treatment appointments for prostate cancer patients, or to confirm tumoral margins for localized ablation procedures. We imaged biopsies from 39 patients undergoing image-guided diagnostic biopsy using a customized SIM system and a dual-color fluorescent hematoxylin & eosin (H&E) analog. The biopsy images had an average size of 342 megapixels (minimum 78.1, maximum 842) and an average imaging duration of 145 s (minimum 56, maximum 322). Comparison of urologist’s suspicion of malignancy based on MRI, to pathologist diagnosis of biopsy images obtained in real time, reveals that real-time biopsy imaging could significantly improve confirmation of malignancy or tumoral margins over medical imaging alone.
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Wu, Qian, Li Hua Wang, Wenguang Chang i Lu Yan Li. "Research on Start-up Time of the Supply Chain Emergency Plan Based on Online Method". Applied Mechanics and Materials 174-177 (maj 2012): 2749–53. http://dx.doi.org/10.4028/www.scientific.net/amm.174-177.2749.
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This paper researches the optimal start-up time of emergency plan adopting online method. In view of this problem, it establishes respectively mathematical models of the single enterprise and the simple supply chain enterprises. And then competitive ratio is introduced to illustrate the effectiveness of start-up strategies. When the whole supply chain enterprises are considered as the research objective, the time asynchronous phenomena when launching the preplan appear between the single enterprise and the whole supply chain. Aimed at this phenomenon, it puts forward coordination mechanism, realizes the optimal response of the whole supply chain for emergencies, and controls the loss emergencies causes to the minimum. The research result has theoretical guidance and practical application value.
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Cree, Ian A., Zandra Deans, Marjolijn J. L. Ligtenberg, Nicola Normanno, Anders Edsjö, Etienne Rouleau, Francesc Solé i in. "Guidance for laboratories performing molecular pathology for cancer patients". Journal of Clinical Pathology 67, nr 11 (10.07.2014): 923–31. http://dx.doi.org/10.1136/jclinpath-2014-202404.
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Molecular testing is becoming an important part of the diagnosis of any patient with cancer. The challenge to laboratories is to meet this need, using reliable methods and processes to ensure that patients receive a timely and accurate report on which their treatment will be based. The aim of this paper is to provide minimum requirements for the management of molecular pathology laboratories. This general guidance should be augmented by the specific guidance available for different tumour types and tests. Preanalytical considerations are important, and careful consideration of the way in which specimens are obtained and reach the laboratory is necessary. Sample receipt and handling follow standard operating procedures, but some alterations may be necessary if molecular testing is to be performed, for instance to control tissue fixation. DNA and RNA extraction can be standardised and should be checked for quality and quantity of output on a regular basis. The choice of analytical method(s) depends on clinical requirements, desired turnaround time, and expertise available. Internal quality control, regular internal audit of the whole testing process, laboratory accreditation, and continual participation in external quality assessment schemes are prerequisites for delivery of a reliable service. A molecular pathology report should accurately convey the information the clinician needs to treat the patient with sufficient information to allow for correct interpretation of the result. Molecular pathology is developing rapidly, and further detailed evidence-based recommendations are required for many of the topics covered here.
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Zhong, Xiaojing, Yukun Yang, Runqing Miao, Yuqing Peng i Guiyun Liu. "Dynamics and intermittent stochastic stabilization of a rumor spreading model with guidance mechanism in heterogeneous network". Chinese Physics B 31, nr 4 (1.03.2022): 040205. http://dx.doi.org/10.1088/1674-1056/ac587d.
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We propose a novel rumor propagation model with guidance mechanism in heterogeneous complex networks. Firstly, the sharp threshold of rumor propagation, global stability of the information-equilibrium and information-prevailing-equilibrium under R 0 < 1 and R 0 > 1 is carried out by Lyapunov method and LaSalle’s invariant principle. Next, we design an aperiodically intermittent stochastic stabilization method to suppress the rumor propagation. By using the Itô formula and exponential martingale inequality, the expression of the minimum control intensity is calculated. This method can effectively stabilize the rumor propagation by choosing a suitable perturb intensity and a perturb time ratio, while minimizing the control cost. Finally, numerical examples are given to illustrate the analysis and method of the paper.
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Blinkhorn, Anthony. "Prehospital emergency anaesthesia: time taken to care for and respond to a critically injured patient". Journal of Paramedic Practice 11, nr 7 (2.07.2019): 296–301. http://dx.doi.org/10.12968/jpar.2019.11.7.296.
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The 2007 National Confidential Enquiry into Patient Outcome and Death (NCEPOD) Trauma: Who Cares? report recommended that people trained to administer anaesthesia and intubate severely injured patients should be available in prehospital environments. Published articles, reference documents and guidance reports were reviewed to compare the management plans and standard operating procedures produced by an ambulance trust in England that provides prehospital emergency anaesthesia (PHEA). Documents reviewed all provide a common un-referenced patient injury list showing indications to perform PHEA but do not state a time frame within which it should be performed. No minimum time before PHEA is started and how long is acceptable to wait for a specialist resource to arrive before an ambulance can transport to a hospital were found. Further work is required to establish and formalise this time frame.
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Bareišis, Ramūnas, Aleksandras Kirka i Rolandas Puronas. "Accuracy, Power Consumption and Environmental Protection of Shuttle Gantry Module in Arable Farming". Solid State Phenomena 113 (czerwiec 2006): 319–24. http://dx.doi.org/10.4028/www.scientific.net/ssp.113.319.
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The theoretical and the experimental researches of guidance, energy consumption and environment protection of the shuttle gantry module are submitted. Influence of a micro-relief, chassis speed differences and correction intensity for accuracy of guidance has been determined. The characteristics of the chassis have more influences for accuracy of guidance than a rough ground. It is not effective to supply more than 60 % of oil flow for the chassis with a lower speed, because it has a negative influence on the accuracy of guidance and on the consumption of power. When distance between the optical sensors is 50 mm, the maximum declination of guidance from mean trajectory is 33 mm. The useful factors and perspectives for energy saving and environment protection are established. The energy demand for chassis and operating working parts do not match in time. 3.5 - 4.5 kW installed power is enough to operate the module. The resistance of the chassis moving through constant technological tracks and that of the implemented carriage moving though beam are low. The energy consumption that is of no avail to soil deformation decreases to minimum. The resistance power of implements passes to the gear. Soil in the plant vegetation zone is not influenced by chassis. Inter-row could be reduced. Thus, there emerges a possibility to satisfy energy demand by alternative energy sources, to reduce pollution, and the deleterious influence on soil features. Direct human participation in technological processes is not required. The dependence on meteorological conditions is reduced. In order to calculate energy consumption, the operation efficiency of implements and chassis was established. Common efficiency of the module is calculated as a reverse value of common working time input. 40 m length beam will allow working at 0.42 ha/h efficiency. Positioning energy is just 0.6 kWh/ha, common one – 8.6 kWh/ha.
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Pellegrino, Marianna, Silvia Caruso, Tiziana Cantile, Gioacchino Pellegrino i Gianmaria Fabrizio Ferrazzano. "Early Treatment of Anterior Crossbite with Eruption Guidance Appliance: A Case Report". International Journal of Environmental Research and Public Health 17, nr 10 (20.05.2020): 3587. http://dx.doi.org/10.3390/ijerph17103587.
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The purpose of this investigation was to show how to manage an anterior crossbite in early mixed dentition with an eruption guidance appliance (EGA). The analyzed clinical case reported an anterior crossbite, a bimaxillary retrusion tendency, and a horizontal growth pattern. The anterior crossbite was an unfavorable occlusal condition that could lead to a class III malocclusion growth pattern. An early treatment approach was suggested to reach a correct sagittal jaw relationship. Hence, the selected approach acted on the dentoalveolar sector, aiming to have effects on the posterior vertical dimension and to improve the sagittal jaw’s relation. An EGA was selected to treat the patient in early mixed dentition. After 7 months of therapy with night-time use, the dental malocclusion was completely resolved. The patient continued to be treated with the same device, used as active retention. With the EGA treatment, the erupting forces, rather than the active forces, were used to resolve the dental malocclusion. This approach allowed a low compliance requirement and had a minimum psychosocial and psychological impact on the patient. The early treatment was essential to give a functional occlusion and a good balance of the soft perioral tissues and muscles.
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Zhang, Yuanxing, Bin Li, Boyuan Cao, Taoyong Li, Xingde Huang i Xingang Yang. "Research on Optimization Control Strategy of Vehicle-Road-Grid Charging and Exchanging Based on User Demand Guidance". Journal of Physics: Conference Series 2025, nr 1 (1.09.2021): 012081. http://dx.doi.org/10.1088/1742-6596/2025/1/012081.
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Abstract Considering the time-space uncertainty of electric vehicle charging and changing demand, the uneven distribution and random diversity of charging stations, the big data cloud network is used to realize the real-time information interaction between charging and changing power station and electric vehicle. Based on the user demand orientation, an intelligent charging and changing optimization control strategy of “Vehicle-Road-Grid” integrating cloud vehicle operation data is proposed. Under the discrete electric vehicle charging demand, this strategy quickly organizes the supply information around the discrete point. On the basis of the minimum energy consumption between the electric vehicle charging request point and the supply point, considering the multi-dimensional factors such as the optimal interests of the electric vehicle users, the shortest waiting time for charging and changing, and the shortest driving distance for charging and changing, the multi-objective optimal configuration strategy is realized. The simulation results show that the strategy can stably select the charging and swapping scheme that best meets the actual needs of users, effectively improve the charging and swapping service experience of users, and enhance the adhesion and participation of users.
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Ma, Ji, David Murphy, Gregory Provan, Cian O'Mathuna i Michael Hayes. "The Evaluation of Direct Volume Rendering-Based Uncertainty Visualization Techniques for 3D Scalar Data". International Journal of Image and Graphics 14, nr 04 (październik 2014): 1450017. http://dx.doi.org/10.1142/s021946781450017x.
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Many techniques have been proposed to represent uncertainty in data visualization. However, little research has been reported on the evaluation of their effectiveness. Moreover, no studies have been conducted to evaluate direct volume rendering (DVR)-based uncertainty visualization techniques. In this paper, we present a novel method that evaluates the perceptual effectiveness of four existing and one proposed DVR-based uncertainty visualization techniques. Four types of searching tasks that include identifying the maximum uncertainty data, identifying the minimum uncertainty data, identifying the maximum scalar data and identifying the minimum scalar data have been involved in this study, and a total of twenty-eight participants have contributed to the final main user study. Our analysis suggested that the proposed linked views and interactive specification (LVIS) technique appears to be the most accurate among all techniques, although it takes the longest task completion time. For the four existing techniques, the overlays technique appears to be the most advantageous, and it takes similar task completion time as the others. We believe that these findings can provide useful guidance for future uncertainty visualization design.
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Filler, Aaron. "MINIMAL ACCESS NERVE SURGERY AND INTERVENTIONAL MAGNETIC RESONANCE IMAGING". Neurosurgery 65, suppl_4 (1.10.2009): A212—A221. http://dx.doi.org/10.1227/01.neu.0000346253.89837.6c.
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Abstract OBJECTIVE Develop and assess the utility of novel minimal access techniques including percutaneous open-configuration interventional magnetic resonance imaging (iMRI), open surgery using open or closed/cylindrical iMRI systems, and minimal access open surgery with electromyographic guidance in a standard operating room. METHODS For more than 2500 percutaneous open iMRI procedures, 25 incisional surgery open iMRI cases, 3 incisional surgery closed/cylindrical iMRI cases, 25 computed tomography–guided percutaneous procedures, and more than 1000 minimal access incisional surgery cases in the standard operating room with electromyographic guidance, cycle time for intraoperative data collection and numbers of guidance events per case were assessed. RESULTS Cycle time varied greatly. The minimum was for open surgery in the standard operating room with direct nerve stimulation for electromyography, requiring 10 to 15 seconds, which was applicable for dozens of assessments during the surgery and had negligible effects on total surgical time. Percutaneous procedures in the open iMRI environment allowed for 20 or 30 imaging events during a procedure, with cycle times of between 10 and 20 seconds. Incisional surgery in the open iMRI system had a cycle time of about 1 to 5 minutes for “in-magnet” procedures and about 5 to 10 minutes for “magnet-adjacent” procedures. Incisional surgery in closed/cylindrical iMRI procedures had a cycle time of 45 to 60 minutes, and the technique proved awkward to use more than once or twice per surgical case. CONCLUSION Percutaneous open-configuration iMRI provides clear benefits over computed tomography or ultrasound. Minimal access surgery and incisional open-configuration iMRI are useful and effective in some situations. Closed/cylindrical iMRI systems pose challenges for patient safety, add greatly to surgical time, and provide limited useful intraoperative benefits.
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Rusdianah, Eva, Mubasysyir Hasanbasri i Mohammad Hakimi. "Clinical learning experiences and professional development: implementation of a district level undergraduate midwifery program in Indonesia". Berita Kedokteran Masyarakat 32, nr 2 (1.02.2016): 73. http://dx.doi.org/10.22146/bkm.27384.
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PurposeThe aim is to examine the suitability of the educational process in place with the expected professional development.MethodWe conducted in-depth interviews with (a) 16 third-year student who recently completed 2-month clinical rotation in the hospital and (b) four teachers.ResultsEvidence from this study indicate weak learning environment. Clinical instructor only has a limited time to meet with students, so that students rarely get the guidance and direct supervision. Students more often obtain “lessons” of the young staff, which many of them indifferent in providing guidance. Students feel insecure and fear in communicating with senior staff from both the nursing and medical professions. Academic lecturers provide minimum learning support. Their supervision does not allow students to reflect on their experiences.ConclusionProfessional development as reflected in clinical rotations in hospitals is still very limited. The government must monitor more strictly, especially for the medical school located in the district, where professional educators are very limited.
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JAFARI, G. R., A. BAHRAMINASAB i P. NOROUZZADEH. "WHY DOES THE STANDARD GARCH(1, 1) MODEL WORK WELL?" International Journal of Modern Physics C 18, nr 07 (lipiec 2007): 1223–30. http://dx.doi.org/10.1142/s0129183107011261.
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The AutoRegressive Conditional Heteroskedasticity (ARCH) and its generalized version (GARCH) family of models have grown to encompass a wide range of specifications, each of them is designed to enhance the ability of the model to capture the characteristics of stochastic data, such as financial time series. The existing literature provides little guidance on how to select optimal parameters, which are critical in efficiency of the model, among the infinite range of available parameters. We introduce a new criterion to find suitable parameters in GARCH models by using Markov length, which is the minimum time interval over which the data can be considered as constituting a Markov process. This criterion is applied to various time series and its results support the known idea that GARCH(1, 1) model works well.
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Fuse, Hiraku, Kenji Komatsu, Hiroyuki Arakawa, Takeji Sakae i Fujisaki Tatsuya. "An infrared interactive patient position guidance and acquisition control system for use during radiotherapy treatment". Journal of Radiotherapy in Practice 16, nr 3 (6.04.2017): 303–10. http://dx.doi.org/10.1017/s1460396917000140.
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AbstractBackgroundThe control of patient position, posture and respiratory movements during radiotherapy is important for effective and specific treatment of malignancy. We have developed an infrared (IR) interactive patient position guidance and acquisition control system for clinical use, comprising IR cameras, IR markers and dedicated software.Materials and methodsWe evaluated the system with ten healthy volunteers and ten experienced operators. IR markers were placed on the body surface. Their positions were calculated using vectors of three translational and three rotational parameters, and the intrafractional error for each marker was acquired with and without respiratory motion. The inclusion of multiple positioning markers allowed for real-time visualisation of the patient posture, with feedback on misalignment and required postural adjustments.ResultsThe positioning time was 73 seconds (with a minimum period of 39 seconds), which was significantly shorter than for conventional line alignment. A comparison of positioning reproducibility between conventional line alignment and this system was <3·5 mm and was not patient dependent or operator dependent. An intrafractional error of displacement of up to 10·0 mm was found in the right iliac crest.ConclusionsThis IR interactive system was shown to be high utility and suitable for monitoring patient position, posture and respiratory movements during radiotherapy.