Deceleration Process Research Articles

The Energy Saving Pumping Unit System Design and Analysis

With the development of oil field production demand today, pumping unit is developing towards the direction of energy saving, intelligent. According to the present status of the oilfield, this paper designed a kind of intelligent energy saving pumping unit system, the system acceleration and deceleration process is very short, most of their working time in uniform motion in a stroke, and the beam pumping unit has been alternating deceleration process all the time compared with good energy saving effect. Energy store system is designed, the system not only reduces energy consumption, and make the motors can be started with initial velocity, shorten the motor start-up time, the motor starting current is stable running current of 4 to 7 times, so that reduces the starting current impact. To test this idea, modeling of motor, and the simulation analysis, the results confirmed the idea very well. Finally, in the principle of the pumping unit system prototype experiments, the experimental results show that the pumping unit system has significant energy-saving effect and the intelligent characteristics.

Numerical investigation of supersonic flow breakdown at the inlet duct throttling

The work presents the results of investigating the process of supersonic flow deceleration in a duct of the two-dimensional inlet throttled by variation of the outlet cross-sectional area. An inlet with three external compression shock waves designed for the freestream Mach number Md = 7 was considered as an example for the investigation. A one-dimensional analysis of the conditions for realization of the supersonic flow deceleration regimes in the inlet duct with two throats — in the inlet entrance and at the inlet duct outlet, has been carried out. The parametric numerical computations of two-dimensional inviscid or turbulent flows in the inlet were performed with the use of the Euler and Navier—Stokes codes of the program package FLUENT. The critical conditions for the nonuniform flow in the outlet throat bringing to choking the inlet duct were determined.

Analysis of train movement dynamics under various temporal–spatial constraints in fixed-block railway network using extended cellular automaton model

In the fixed-block railway traffic, the trains adjust their speeds in view of their preceding allowable spaces caused by their respective front adjacent trains or specified by scheduling commands. The railway lines have the line-type speed limits within some block sections and the point-type ones at the terminals of block sections. Those speed limits originate from line conditions, scheduling commands and indications of signal equipment. This paper attempts to in detail reveal the train movement mechanism synthetically considering those temporal–spatial constraints. The proposed train movement model defines four kinds of target points and utilizes them to successively engender the instantaneous target points with their corresponding target speeds. It adopts the rule-based description mechanism in cellular automata (CA) but with continuous spaces to replicate restrictive, autonomous and synergistic behaviors of and among trains. The selections of accelerations and decelerations are based upon the data models of practical acceleration and deceleration processes; thereupon, the model is data-driven. The analysis of train movement dynamics through case studies demonstrates that the extended CA model can reproduce the train movement mechanism of grading speed control to satisfy the aforementioned temporal–spatial constraints. The model is applicable to represent the as-is or should-be states of train movements when adjustable parameters are properly configured.

Getting a grip on the transverse motion in a Zeeman decelerator

Zeeman deceleration is an experimental technique in which inhomogeneous, time-dependent magnetic fields generated inside an array of solenoid coils are used to manipulate the velocity of a supersonic beam. A 12-stage Zeeman decelerator has been built and characterized using hydrogen atoms as a test system. The instrument has several original features including the possibility to replace each deceleration coil individually. In this article, we give a detailed description of the experimental setup, and illustrate its performance. We demonstrate that the overall acceptance in a Zeeman decelerator can be significantly increased with only minor changes to the setup itself. This is achieved by applying a rather low, anti-parallel magnetic field in one of the solenoid coils that forms a temporally varying quadrupole field, and improves particle confinement in the transverse direction. The results are reproduced by three-dimensional numerical particle trajectory simulations thus allowing for a rigorous analysis of the experimental data. The findings suggest the use of a modified coil configuration to improve transverse focusing during the deceleration process.

Ejecta mobility of layered ejecta craters on Mars: Assessing the influence of snow and ice deposits

The unusual lobate ejecta deposits of martian impact craters have led to several proposed fluidization mechanisms to explain their morphology. Of the fluidized ejecta craters, double-layered ejecta (DLE) craters, believed to form in a decameters-thick surface ice layer, appear to have anomalously large and highly variable ejecta mobility (EM) ratios. We propose that low-aspect-ratio layered ejecta (LARLE) craters also form in a decameters-thick surface ice layer, in a manner similar to the formation of DLE craters, and pedestal (Pd) craters. We assess the hypothesis that the anomalously large EM values of DLE and LARLE craters are the result of ejecta flight, emplacement, and sliding of the ejecta on a lubricating ice layer, and that the highly variable EM values are related to variations in surface ice layer thickness. We find that the presence of a variable thickness icy substrate at the time of impact combined with varying coefficients of sliding friction and/or particle size, are consistent with the high values and wide range of EM values observed for these craters: thicker icy substrates lead to greater amounts of atmospheric drag and deceleration of the icy material due to the small fragmentation diameter of ice generated by its low tensile strength. Additionally, the vaporization of ejected icy material and entrainment of the vaporized material in a late-stage vapor plume further reduces the average ejecta velocities. By preferentially decelerating the smaller icy particles and eliminating the vaporized ice material from the ejecta curtain, the highest velocity ejecta is eliminated, and runout distance is decreased. We find that a similar model involving variations in the target structure of a volatile-rich substrate may also explain the formation of single-layered ejecta (SLE) and multiple-layered ejecta (MLE) craters. The lack of ramparts around the outer ejecta facies of craters that form in surface ice (DLE, LARLE) may indicate that ejecta emplaced on surface ice avoids significant deceleration due to the low basal μ values, and that ramparts around SLE and MLE craters may be indicative of ejecta deceleration processes.

Influence of velocity profile on the chip thickness and material removal rate in milling

In milling process, the tool path presents discontinuities in changing direction. The explicit form of the material removal rate was determined by the product of cross-section and the feed rate. This method was not accurate in the case of acceleration and deceleration process at the discontinuities. Based on the true trajectories, the cutter geometries and the velocity profiles, this paper present a method for determining the material removal rate of different end mills which considers the Acc/Dec process.

Smart eye using Ultrasonic sensor in Electrical vehicles for Differently Able.

In this competitive world, electrical vehicles play a vital role. The cost of fuel is rising day by day. In order to meet this issue we need a vehicle that can overcome these problems. Physically challenged people prefer electric vehicles which are more convenient and reliable for them to travel. Controlling the speed in electric vehicles has been a major drawback, which needs to be rectified. The proposed system uses ultra-sonic sensors and controls the speed of the vehicle automatically. The ultrasonic sensors measure the distance of the obstacle and according to the corresponding distance the speed of the vehicle is regulated and reduced gradually. All these processes are carried out by automatic acceleration and deceleration without the guidance of the person driving the vehicle. The process of acceleration and deceleration is more important for controlling the speed of the electric vehicle. The speed is controlled proportional to the distance of the obstacle from the vehicle. Thus it can safely decelerate the speed and turn away from the obstacles. This system ensures safety while driving for the physically challenged person. In addition to the features of ultrasonic sensor, an infrared sensor is also used to avoid collision with obstacles. The variations in the pulse width with respect to changes in the speed is inferred using simulation of Proteus software. Keywords: ultra-sonic sensor, infrared sensor, smart eye.

Design of a 6-DOF upper limb rehabilitation exoskeleton with parallel actuated joints.

In this paper, a 6-DOF wearable upper limb exoskeleton with parallel actuated joints which perfectly mimics human motions is proposed. The upper limb exoskeleton assists the movement of physically weak people. Compared with the existing upper limb exoskeletons which are mostly designed using a serial structure with large movement space but small stiffness and poor wearable ability, a prototype for motion assistance based on human anatomy structure has been developed in our design. Moreover, the design adopts balls instead of bearings to save space, which simplifies the structure and reduces the cost of the mechanism. The proposed design also employs deceleration processes to ensure that the transmission ratio of each joint is coincident.

Braking of high-speed flows in the magnetotail: THEMIS joint observations

The motion and deceleration processes of plasma sheet high-speed flows have great significance to magnetospheric particle acceleration, magnetic field perturbation, magnetic flux transport, triggering of substorm, and the current system formation in the magnetotail. From February to April 2009, two satellites of the Time History of Events and Macroscale Interactions during Substorms mission, THA and THE, were often separated largely in Z direction, but had small X and Y separations. Such special configuration allows simultaneous observations of high-speed flows at the center and boundary of the plasma sheet. Based on selected case study and statistical analysis, it is found that for about 89 % of the events we selected, the probe further away from the neutral sheet observed the high-speed flow earlier than the one close to the center, and the flow is mainly field aligned. And for about 95 % events the probe further away from the neutral sheet observed higher X component of the plasma flow. With the hypothesis that parallel flow keeps the same speed during its earthward propagation while central plasma sheet stream uniformly or suddenly brakes on its way to the earth, we deduced the position where the deceleration begins to be between 13 Re and 17 Re downtail, where the near-earth reconnection is supposed to occur. In addition, our statistical results show that dipolarization fronts observed in the central plasma sheet are more prominent than those observed in the plasma sheet boundary layer ahead of the high-speed flow.

Experimental research on the effectiveness of speed reduction markings based on driving simulation: A case study

The objective of this paper is to test the effectiveness of speed reduction markings (SRMs). The empirical data including vehicle operations and drivers’ psychological and physical reactions were collected in a driving simulator. An index—the relative speed difference—was developed to evaluate the effectiveness of speed reduction markings. Researchers analyzed data to test the effectiveness of speed reduction markings and quantitatively study their effects and the deceleration process. Out of 15 subjects, there were 1 (7%), 2 (13%), and 7 (47%) subjects who decelerated while driving through the downhill section in the No SRMs scenario, Longitudinal SRMs scenario and Transverse SRMs scenario, respectively. In terms of speed and subjects’ decelerating maneuver, the results of the analysis of variance (ANOVA) and the contrast analysis (S–N–K method) showed that transverse speed reduction markings (TSRMs) could significantly influence subjects’ speed choice and maneuver (P<0.05).

An Optimization Design Method for the Acceleration and Deceleration Curves of Detachable Ropeway

It will influence the comfort and safety of passengers when the cabins accelerating and decelerating in the detachable ropeway station. A dynamic model was built for the acceleration and deceleration process of detachable ropeway. And the optimal S acceleration and deceleration curves were designed. Then a physical model of detachable ropeway was built and imported into Adams to make a motion simulation. In order to ensure a small swinging angle when the cabins accelerating or decelerating to a constant velocity, it was compared with the swinging angle and swing in the condition of uniform acceleration and uniform deceleration. And the swinging angle and swing were reduced clearly in the condition of S acceleration and deceleration curves. It can greatly improve the comfort and safety of passengers under the S acceleration and deceleration curves.

A study of non-isothermal kinetics of limestone decomposition in air (O2/N2) and oxy-fuel (O2/CO2) atmospheres

The non-isothermal experiments of limestone decomposition at multi-heating rates in O2/N2 and O2/CO2 atmospheres were studied using thermogravimetry. The limestone decomposition kinetic model function, kinetic parameters of apparent activation energy (E), and pre-exponential factor (A) were evaluated by Bagchi and Malek method. The results shown that in 20 % O2/80 % N2 atmosphere, the limestone decomposed slowly following the contracting sphere volume model controlled by boundary reaction (spherical symmetry) in two stages, and the E increased by about 50 kJ mol−1 in the second decomposition stage. But in 20 % O2/80 % CO2 atmosphere, the presence of high-concentration CO2 significantly inhibited the limestone decomposition, and made the decomposition process occur at high temperature with a rapid rate; the decomposition kinetics was divided into three stages, the first stage was an accelerated decomposition process following the Mampel Power law model with the exponential law equation, the second stage followed the nth order chemical reaction model as an α–t deceleration process, and the third stage belonged to the random nucleation and nuclei growth model with the Avrami–Erofeev equation. And with the heating rate increasing, the reaction order n showed a slight rise tendency. The E was about 1,245 kJ mol−1 in 20 % O2/80 % CO2 atmosphere, but was only about 175 kJ mol−1 in 20 % O2/80 % N2 atmosphere. The E and A increased markedly in the O2/CO2 atmosphere.

An extrapolation approach for aeroengine’s transient control law design

Transient control law ensures that the aeroengine transits to the command operating state rapidly and reliably. Most of the existing approaches for transient control law design have complicated principle and arithmetic. As a result, those approaches are not convenient for application. This paper proposes an extrapolation approach based on the set-point parameters to construct the transient control law, which has a good practicability. In this approach, the transient main fuel control law for acceleration and deceleration process is designed based on the main fuel flow on steady operating state. In order to analyze the designing feature of the extrapolation approach, the simulation results of several different transient control laws designed by the same approach are compared together. The analysis indicates that the aeroengine has a good performance in the transient process and the designing feature of the extrapolation approach conforms to the elements of the turbofan aeroengine.

Evaluation of association between atherogenic index of plasma and intima‐media thickness of the carotid artery for subclinic atherosclerosis in patients on maintenance hemodialysis

Incidence of cardiovascular diseases in the patients having chronic kidney disease (CKD) is between 25% and 60%. This increased rate is proposed to be associated with "accelerated atherosclerosis." Increased carotid intima-media thickness (CIMT) is a subclinical atherosclerosis marker. Small-dense low-density lipoprotein particles are a strong risk factor for atherosclerosis. It was shown that atherogenic index of plasma (AIP = log(TG/HDL-c)) is correlated with size of the lipoprotein particles. We investigated the correlation between AIP and CIMT which is a subclinical atherosclerosis marker, in hemodialysis (HD) patients. A total of 62 persons with 31 patients under HD therapy and 31 volunteers were included in the study. In all the participants, CIMT was measured and AIP were calculated. AIP and CIMT values of the participants were compared with blood pressures, lipid profiles and the other risk factors. AIP (0.39 ± 0.32) and CIMT (0.57 ± 0.13) were found significantly higher in the patient group than in the controls (0.04 ± 0.36 and 0.45 ± 0.119, respectively); (P = 0.0001 and 0.0001, respectively). There was a significant correlation between AIP and increased CIMT in the patient group (P = 0.0001, r = 0.430). Among the lipid parameters, the strongest correlation was found between CIMT and AIP. We demonstrated the significant increase of AIP and CIMT in HD patients. A correlation was found between AIP and CIMT. AIP was found to show a correlation with a greater number of risk factors, both classical and CKD specific, than CIMT. These data suggest that AIP might be a method which can be used both in diagnosis of subclinical atherosclerosis and in deceleration processes of its progression.

Nuclear fusion in ordered crystal targets bombarded by monochromatic beams of light or middle-mass isotopes

In ordered crystal lattice there is very strong influence of crystal axes and planes electrical field on motion and interaction of fast charged particles with crystal atoms and nuclei. It is shown that in mono-crystal targets like LiD the rate of fusion process with the participation of both target nuclei (e.g. D) and beam of fast nuclei (e.g. T), directed at Lindhard angle, may be increased by 10–100 times compared to the alternative process of deceleration on atomic electrons. Such changes are based on the use of specific channeling physics regime of motion – “overbarrier motion”. At such regime the processes of spatial redistribution and dechanneling of accelerated ions take place. In this article the methods of optimization and practical realization of such a nuclear fusion are discussed in details.Another method for radical optimization of fusion processes with the use of monochromatic beams of middle mass isotopes is proposed. The features of optimized nuclear fusion model based on resonant tunneling effect were considered. This leads, in combination with the use of particle beams with optimum energy and energy spread, which correspond to total transparency “window” of reaction barrier, to the possibility of positive nuclear fusion energy release on one atomic monolayer! Such effect can be regarded as nuclear super absorption of accelerated beam. The possibility of nuclear reactions C12+O16 and C12+O18 at such motion regime with positive energy release is examined.

Impact experiments of exotic dust grain capture by highly porous primitive bodies

Small primitive bodies were presumably highly porous when they formed and some still have low densities that are indicative of a high pore content. Therefore, after their formation, interplanetary dust impacting on their surface may have been captured because of their porous structure. The mechanism of dust penetration is thus of importance to understand the evolution of small bodies and the origin of their internal dust particles. Impact experiments of sintered glass-bead targets characterized by 80%, 87%, and 94% bulk porosity were conducted using metal and basalt projectiles at impact velocities ranging from 1.6 to 7.2kms−1. Track morphology and penetration processes were analyzed using both X-ray tomography and a flash X-ray system. Two types of track were observed, as previously also found in the Stardust aerogel: a thin and long track (carrot-shaped track), and a “bulb” with tails (bulb-shaped track). The track shape changed with initial dynamic pressure. We found that the transition between “carrot” and “bulb” occurred at a pressure of roughly 20 times the projectile’s tensile strength. The deceleration process of projectiles without severe deformation and fragmentation was reproduced by a drag equation composed of an inertia drag that was proportional to the square of the projectile’s velocity and a constant drag proportional to the target’s compressive strength. We applied this deceleration equation to silicate dust penetrating into hypothetical porous icy bodies which were homogeneous on much smaller scales than the impacting dust particles. The penetration depth was approximately 100 times the projectile diameter for the bodies with 90% porosity.

Parameter Modeling Method for Aeroengine Virtual Testing System

Aeroengine parameters model is pivotal for development of aeroengine virtual testing system. So the modeling method is discussed in this paper in detail. Firstly, dependency relationships between parameters are established according to the variational character of each parameter in different working state, including transient processes such as false start, cold run, start, acceleration, deceleration, stop and stable processes such as idle, warming, performance test. Then parameter equations are formulated based on least square fit, utilizing actual test data of some kind of turbo-fan aeroengine as prototype. With the method, modeling work for aeroengine virtual testing system is facilitated. And each parameter varying pattern is consistent to that of real aeroengine. Furthermore, different test process can be simulated via changing relevant setting parameters. It makes the development of aeroengine virtual testing system much easier.

Knowledge Mediators and Lubricating Channels: On the Temporal Politics of Remissioning the University

Engaging with the work of Hartmut Rosa, this article offers an account of the politics of time in the contemporary corporatizing and enterprising university. It examines the emerging “third mission” for the university, and the ways in which this has enabled an array of new actors and their projects and practices to operate in, and on, university spaces that in turn are aimed at reworking the socialities, spatialities and temporalities of university life. Drawing on empirical work, we focus particularly on a new kind of knowledge worker in the academy—the knowledge mediators/broker—whose task it is to create the spaces and channels that move ideas between the university and the wider economy and back again, to negotiate and help navigate ideas from the world of business into the university, and to accelerate the development of ideas into marketable, scalable and profitable goods and services. Yet, we also show that these processes of acceleration are accompanied by a paradoxical set of counter-flows, undercurrents and backflows, which feed processes of deceleration. We conclude by thinking through what a counter-hegemonic project might look like that critiques and recreates a new politics of time to underpin the conditions for new forms of knowledge creation in the academy.

A real time dose monitoring and dose reconstruction tool for patient specific VMAT QA and delivery

To develop a real time dose monitoring and dose reconstruction tool to identify and quantify sources of errors during patient specific volumetric modulated arc therapy (VMAT) delivery and quality assurance. The authors develop a VMAT delivery monitor tool called linac data monitor that connects to the linac in clinical mode and records, displays, and compares real time machine parameters with the planned parameters. A new measure, called integral error, keeps a running total of leaf overshoot and undershoot errors in each leaf pair, multiplied by leaf width, and the amount of time during which the error exists in monitor unit delivery. Another tool reconstructs Pinnacle(3)™ format delivered plan based on the saved machine logfile and recalculates actual delivered dose in patient anatomy. Delivery characteristics of various standard fractionation and stereotactic body radiation therapy (SBRT) VMAT plans delivered on Elekta Axesse and Synergy linacs were quantified. The MLC and gantry errors for all the treatment sites were 0.00 ± 0.59 mm and 0.05 ± 0.31°, indicating a good MLC gain calibration. Standard fractionation plans had a larger gantry error than SBRT plans due to frequent dose rate changes. On average, the MLC errors were negligible but larger errors of up to 6 mm and 2.5° were seen when dose rate varied frequently. Large gantry errors occurred during the acceleration and deceleration process, and correlated well with MLC errors (r = 0.858, p = 0.0004). PTV mean, minimum, and maximum dose discrepancies were 0.87 ± 0.21%, 0.99 ± 0.59%, and 1.18 ± 0.52%, respectively. The organs at risk (OAR) doses were within 2.5%, except some OARs that showed up to 5.6% discrepancy in maximum dose. Real time displayed normalized total positive integral error (normalized to the total monitor units) correlated linearly with MLC (r = 0.9279, p < 0.001) and gantry errors (r = 0.742, p = 0.005). There is a strong correlation between total integral error and PTV mean (r = 0.683, p = 0.015), minimum (r = 0.6147, p = 0.033), and maximum dose (r = 0.6038, p = 0.0376). Errors may exist during complex VMAT planning and delivery. Linac data monitor is capable of detecting and quantifying mechanical and dosimetric errors at various stages of planning and delivery.

Acceleration and deceleration of coronal mass ejections during propagation and interaction

A major challenge to the space weather forecasting community is accurate prediction of Coronal Mass Ejections (CMEs) induced Shock Arrival Time (SAT) at Earth's environment. In order to improve the current accuracy, one of the steps is to understand the physical processes of the acceleration and deceleration of a CME's propagation in the heliosphere. We employ our previous study of a three‐dimensional (3D) magnetohydrodynamic (MHD) simulation for the evolution of two interacting CMEs in a realistic ambient solar wind during the period 28–31 March 2001 event to illustrate these acceleration and deceleration processes. The forces which caused the acceleration and deceleration are analyzed in detail. The forces which caused the acceleration are the magnetic pressure term of Lorentz force and pressure gradient. On the other hand, the forces which caused the deceleration are aerodynamic drag, the Sun's gravity and the tension of magnetic field. In addition the momentum exchange between the solar wind and the moving CMEs can cause acceleration and deceleration of the CME which are now analyzed. In this specific CME event 28–31 March 2001 we have analyzed those forces which cause acceleration and deceleration of CME with and without interaction with another CME. It shows that there are significant momentum changes between these two interacting CMEs to cause the acceleration and deceleration.