Design of innovative solutions for high-pressure fuel injection systems, optimization of measuring techniques for injected flow-rate and modeling of 1D flows

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Undifferentiated High-grade Pleomorphic Sarcoma (Malignant Fibrous Histiocytoma ) Occurring in the Nerve Root: A Rare Case Report and Review of the Literature

Introduction: undifferentiated pleomorphic sarcoma (UPS) represents a group of pleomorphic mesenchymal neoplasms without any defined cell differentiation, occurs more commonly in the extremities. However, we report a rare case of UPS, not malignant peripheral nerve sheath tumor (MPNST) in which the nerve root of the forth cervical vertebrae and adjacent tissues were involved. Presentation of Case: Histopathologically, this tumor was composed of highly atypical spindle cells, pleomorphic cells and multinucleated giant cells. Nuclear mitoses were frequently observed. Immunohistochemistrical results showed that the tumor cells stained positively for vimentin but negatively for all the other immunomarkers.Conclusion: We here reported an extremely rare case of UPS arising from the nerve root of the forth cervical vertebrae and proposed a hypothesis “tumors without any expression of neural markers should be diagnosed as UPSs, not MPNSTs, even though which may arise from peripheral nerve branches”

Embodied Footprints: A Safety-guaranteed Collision Avoidance Model for Numerical Optimization-based Trajectory Planning

Numerical optimization-based methods are among the prevalent trajectory planners for autonomous driving. In a numerical optimization-based planner, the nominal continuous-time trajectory planning problem is discretized into a nonlinear program (NLP) problem with finite constraints imposed on finite collocation points. However, constraint violations between adjacent collocation points may still occur. This study proposes a safety-guaranteed collision-avoidance modeling method to eliminate the collision risks between adjacent collocation points in using numerical optimization-based trajectory planners. A new concept called embodied box is proposed, which is formed by enlarging the rectangular footprint of the ego vehicle. If one can ensure that the embodied boxes at finite collocation points are collide-free, then the ego vehicle's footprint is collide-free at any a moment between adjacent collocation points. We find that the geometric size of an embodied box is a simple function of vehicle velocity and curvature. The proposed theory lays a foundation for numerical optimization-based trajectory planners in autonomous driving.Comment: 12 pages, 13 figure

The Polytropic Approach in Modeling Compressible Flows Through Constant Cross-Section Pipes

A compressible flow with wall friction has been predicted in a constant cross section duct by means of a barotropic modeling approach, and new analytical formulas have been proposed that also allow any possible heat transfer to the walls to be taken into account. A comparison between the distributions of the steady-state flow properties, pertaining to the new formulas, and those of a classic Fanno analysis has been performed. In order to better understand the limits of the polytropic approach in nearly chocked flow applications, a numerical code, which adopts a variable polytropic coefficient along the duct, has been developed. The steady-state numerical distributions along the pipe, obtained for either a viscous adiabatic or an inviscid diabatic flow by means of this approach, coincide with those of the Fanno and Rayleigh models for Mach numbers up to 1. A constant polytropic exponent can be adopted for a Fanno flow that is far from choking conditions, while it cannot be adopted for the simulation of a Rayleigh flow, even when the flow is not close to choking conditions. Finally, under the assumption of diabatic flows with wall friction, the polytropic approach, with a constant polytropic exponent, is shown to be able to accurately approximate cases in which no local maximum is present for the temperature along the duct. The Mach number value at the location where the local maximum temperature possibly occurs has been obtained by means of a new analytical formula

An injected quantity estimation technique based on time–frequency analysis

An innovative injected quantity estimation method, based on time–frequency analysis, has been developed for passenger car Common-Rail (CR) injection systems. This method involves capturing the pressure time history from a transducer installed along the rail-to-injector pipe, and its overall accuracy has been found to be within 1.5 mg. The dependence of the injected mass on the fuel temperature has been investigated, and the correlation of the injected mass with the nominal rail pressure and the energizing time has been evaluated for different thermal regimes. It has been verified that if the duration of the hydraulic injection is considered instead of the energizing time, the influence of the temperature on the injected mass is implicitly taken into account. Thus, the corresponding correlations between the injected mass and the duration of the hydraulic injection have been obtained for different nominal rail pressures. The duration of the hydraulic injection has been measured through an effective time–frequency analysis technique, which has been used to realize a virtual sensor of the needle lift. The experimental campaign has been performed over a wide range of working conditions for single injections, and the accuracy of the innovative prediction methodology, which can be exploited to design a closed-loop control of the injected mass, has been assessed

Joint Dispatching and Cooperative Trajectory Planning for Multiple Autonomous Forklifts in a Warehouse: A Search-and-Learning-Based Approach

Dispatching and cooperative trajectory planning for multiple autonomous forklifts in a warehouse is a widely applied research topic. The conventional methods in this domain regard dispatching and planning as isolated procedures, which render the overall motion quality of the forklift team imperfect. The dispatching and planning problems should be considered simultaneously to achieve optimal cooperative trajectories. However, this approach renders a large-scale nonconvex problem, which is extremely difficult to solve in real time. A joint dispatching and planning method is proposed to balance solution quality and speed. The proposed method is characterized by its fast runtime, light computational burden, and high solution quality. In particular, the candidate goals of each forklift are enumerated. Each candidate dispatch solution is measured after concrete trajectories are generated via an improved hybrid A* search algorithm, which is incorporated with an artificial neural network to improve the cost evaluation process. The proposed joint dispatching and planning method is computationally cheap, kinematically feasible, avoids collisions with obstacles/forklifts, and finds the global optimum quickly. The presented motion planning strategy demonstrates that the integration of a neural network with the dispatching approach leads to a warehouse filling/emptying mission completion time that is 2% shorter than the most efficient strategy lacking machine-learning integration. Notably, the mission completion times across these strategies vary by approximately 15%

A novel fuel injected mass feedback-control for single and multiple injections in direct injection systems for CI engines

A new feedback-control capable to enhance the fuel injected quantity accuracy has been proposed and tested. The experimental pressure in the rail and that measured along the rail-to-injector pipe, in the vicinity of the injector inlet, have been used as input data to a home-made hydraulic model. By means of this model the pressure downstream of the gauged orifice at the interface between the rail and the rail-to-injector pipe is determined; the mass at the injector inlet can be obtained by means of an integration of the estimated flow-rate entering the injector. A robust mathematical law can be established between the mass that enters the injector and the one injected, thus, a feedback-control based on the error between the target injected quantity stored in the ECU and the predicted injected mass has been designed and implemented for the ET correction. The new feedback-strategy has been applied to control both single and double (pilot-main) injection schedules by using a rapid prototyping hardware. Regarding single shots, the new control results to be capable of reducing the injected mass inaccuracy, which is due to the different thermal regimes experienced by the injector, below 0.6 mg (the standard open loop control can feature an error up to 2 mg when the fuel tank temperature is varied), while for the pilot-main schedules it is possible to dramatically reduce the inaccuracy on the desired overall injected quantity (below 1 mg) when digital or continuous rate shaping strategies are implemented