Low-speed Mode Research Articles

Research on Driving Assistance of Electric Cart Using Low-Speed Mode

Research on Driving Assistance of Electric Cart Using Low-Speed Mode

Determination of snow stresses under vehicle loads

Abstract This paper presents results of two experiments on snow stress measurements under vehicles running over snow pack. In the experiments, a 5.6 T 4 × 4 military truck and a grooming machine were used. The military truck was driven over a 30-cm shallow snow pack in which a stress state transducer (SST) was installed. The grooming machine was driven over a 170-cm deep snow pack, in which four pressure sensors were installed at four different depths: 10, 20, 30, and 40 cm. Stress state in snow under the military truck was determined for rolling and for driving (pulling tests at high slip) modes and also for multiple passes. Stresses under the grooming machine were measured during low-speed rolling mode and multiple passes.

Experimental Study of Dynamics of Plasma Expansion in a Vacuum-Arc Discharge and Anode Temperature Calculations

The given work was aimed to experimental studies of a plasma channel expansion in a vacuum-arc discharge between the CuCr50 electrodes; with the anode temperature calculated in this stage. Time dependences of an arc channel diameter have been obtained using a high-speed multiframing image analog camera. In addition, plasma expansion velocities V have been determined for different discharge electric currents. It has been demonstrated that V under the experiment conditions does not depend on the current value, nor it does on the presence or absence of the external axial magnetic field. The experiments show that when the electrodes differ in size, the arc discharge initiated in the center of the cathode expands with time until it reaches the size of a smaller electrode while keeping a cylindrical form. The obtained data on V were used for calculation of the anode temperature. Variations of the power supply and of the heating zone sizes with time as well as evaporation loss have been taken into account in the adopted model. It was shown that in the high-speed expansion mode, an anode spot appeared by insignificant heating of the anode. In the low-speed expansion mode, high heating of the anode is possible, with anode intense evaporation taking place. The anode temperature in stage of discharge gap fill by plasma during electric current commutation has been calculated.

Development, Characterization, and Application of a Versatile Single Particle Detection Apparatus for Time-Integrated and Time-Resolved Fluorescence Measurements—Part II: Experimental Evaluation

This paper describes the experimental realization and characterization of a versatile single particle detection apparatus. The system utilizes a novel particle beam inlet that can serve as either an on-line particle concentrator (i.e., all diameters confined in a narrow beam) or as a segregator (i.e., selected diameters confined in a narrow beam) and can be operated in a high-speed mode as well as in a low-speed mode, thus allowing different interaction times between the particles and the laser beam. An aerodynamic sizing technique has been incorporated into the system to provide rapid, real-time, and high-resolution sizing. Parameters such as transmission efficiency and size-segregation efficiency have been measured. The performance of the instrument has been demonstrated by on-line detection of spectrally resolved and time resolved fluorescence detection from airborne dye-doped particles and aerosolized endogenous fluorophores found in biological agents.

An Application of a Variable Overpower Trip Function with Multiple Ceilings into an Advanced Integral Reactor

A series of evaluations for an inadvertent control rod withdrawal event has been performed to identify the appropriateness of the reactor protection system of a 65 MWt advanced integral reactor by using the Transients And Setpoint Simulation/System-integrated Modular Reactor (TASS/SMR) code. Evaluation results show that, if considering only a high core power trip function as the reactor protection system for the limitation of a core power increase, the occurrence of an inadvertent control rod withdrawal event at the lower core power levels under a high speed mode of a main coolant pump (MCP) results in a significant deterioration in the safety margin. Specially, a violation of a safety limit is possible under the MCP middle and low speed modes due to an unsuitable setpoint of the high core power trip function. To enhance the safety margin, a variable overpower trip (VOPT) function having multiple ceilings according to the MCP speed mode has been implemented into the reactor protection system for the 65 MWt advanced integral reactor. Reassessments by considering the VOPT function with multiple ceilings show that a safety enhancement in the case of an inadvertent control rod withdrawal event is obtained by a timely initiation of a reactor trip.

REDUCING GREENHOUSE EMISSIONS AND FUEL CONSUMPTION: Sustainable Approaches for Surface Transportation

Climate change is rapidly becoming known as a tangible issue that must be addressed to avoid major environmental consequences in the future. Recent change in public opinion has been caused by the physical signs of climate change–melting glaciers, rising sea levels, more severe storm and drought events, and hotter average global temperatures annually. Transportation is a major contributor of carbon dioxide (CO2) and other greenhouse gas emissions from human activity, accounting for approximately 14 percent of total anthropogenic emissions globally and about 27 percent in the U.S. Fortunately, transportation technologies and strategies are emerging that can help to meet the climate challenge. These include automotive and fuel technologies, intelligent transportation systems (ITS), and mobility management strategies that can reduce the demand for private vehicles. While the climate change benefits of innovative engine and vehicle technologies are relatively well understood, there are fewer studies available on the energy and emission impacts of ITS and mobility management strategies. In the future, ITS and mobility management will likely play a greater role in reducing fuel consumption. Studies are often based on simulation models, scenario analysis, and limited deployment experience. Thus, more research is needed to quantify potential impacts. Of the nine ITS technologies examined, traffic signal control, electronic toll collection, bus rapid transit, and traveler information have been deployed more widely and demonstrated positive impacts (but often on a limited basis). Mobility management approaches that have established the greatest CO2 reduction potential, to date, include road pricing policies (congestion and cordon) and carsharing (short-term auto access). Other approaches have also indicated CO2 reduction potential including: low-speed modes, integrated regional smart cards, park-and-ride facilities, parking cash out, smart growth, telecommuting, and carpooling.

The Effect of Intermittent Low Speed Mode Upon Aortic Valve Opening in Calves Supported With a Jarvik 2000 Axial Flow Device

We assessed the effects of an axial flow left ventricular assist device (LVAD) upon aortic valve opening, pump outflow, and biologic and hematologic parameters when operated in intermittent low speed (ILS) mode. An ILS controller equipped Jarvik 2000 LVAD was implanted in six calves. Pump speed was maintained at 10,000 rpm, and pump outflow was measured throughout the study period (71 +/- 6 days [mean +/- SD]). Hematologic and biochemical parameters were analyzed daily for the first 10 days, weekly for the first month, and biweekly thereafter to monitor for kidney or liver dysfunction, hemolysis, bleeding, or infection. Before study termination, esmolol hydrochloride was infused to induce low cardiac output and totally impair aortic valve opening. Radiopaque cineaortography was performed over 30 second intervals (10 seconds before, 10 seconds during, and 10 seconds immediately after ILS controller activation) to assess the effect of ILS mode upon aortic valve opening. After study termination, major end organs and the major vascular tree were removed and examined macroscopically and histologically for thrombus formation and infarction; the aortic valve was examined for thickening and fusion. All pumps were explanted and examined for thrombus formation. All six calves recovered without surgical or mechanical complications. Hematologic and biochemical parameters did not change significantly between baseline and study termination. The aortic valve successfully opened when ILS mode was activated, even under low cardiac output conditions. No thrombus was detected in the major end organs and vascular tree, except for some small renal infarcts in three calves that did not affect renal function. These results indicate that operating an axial flow LVAD in ILS mode allows aortic valve opening and aortic root washout.

Improving California's Bay Area Rapid Transit District Connectivity and Access with Segway Human Transporter and Other Low-Speed Mobility Devices

To evaluate the potential for low-speed modes to improve transit access, the EasyConnect field test will offer shared-use Segway Human Trans porters (HT), electric bicycles, and bicycles linked to a Bay Area Rapid Transit District station and surrounding employment centers in Califor nia. Because of safety concerns, research was conducted to understand the risks associated with these modes and potential risk factors. A review of the safety literature indicates that user error is the major cause of low-speed mode crashes, and significant risk factors are poor surface condi tions and obstructions to drivers' vision. As a result, an extensive training program and carefully selected routes have been included in the field test. The regulatory and legislative history of the HT is chronicled to under stand how concerns about its interaction with pedestrians have produced legislation that includes specific safety requirements. The low-speed modes used in this project will be equipped with safety devices, and part...

Improving California's Bay Area Rapid Transit District Connectivity and Access with Segway Human Transporter and Other Low-Speed Mobility Devices

To evaluate the potential for low-speed modes to improve transit access, the EasyConnect field test will offer shared-use Segway Human Transporters (HT), electric bicycles, and bicycles linked to a Bay Area Rapid Transit District station and surrounding employment centers in California. Because of safety concerns, research was conducted to understand the risks associated with these modes and potential risk factors. A review of the safety literature indicates that user error is the major cause of low-speed mode crashes, and significant risk factors are poor surface conditions and obstructions to drivers’ vision. As a result, an extensive training program and carefully selected routes have been included in the field test. The regulatory and legislative history of the HT is chronicled to understand how concerns about its interaction with pedestrians have produced legislation that includes specific safety requirements. The low-speed modes used in this project will be equipped with safety devices, and participants will be required to wear helmets. The survey results of 13 HT implementation projects provide insight into potential advantages and challenges to the field test. Results of interviews and meetings with field test stakeholders are presented with a discussion of their influence on the field test design. Finally, conclusions and future project steps are discussed.

Rotational infrared polarization modulator using a MEMS-based air turbine with different types of journal bearing

This paper describes rotational infrared polarization modulators using a micro-electromechanical-system-based (MEMS-based) air turbine with different types of journal bearing. Three types of journal bearing, circular, symmetrical two-lobed and asymmetrical seven-lobed journal bearing, were compared. Using an optical displacement meter and a high speed camera, it was confirmed that all turbines exhibit three modes of rotation: (a) low speed mode, (b) intermediate mode and (c) high speed mode in this order, when decreasing N2 flow rate to an aerostatic thrust bearing. In the low speed mode, the rotor is lifted up by excess flow to the thrust bearing, making a contact with an upper layer. In the high speed mode, the rotor is levitated without any contact to the upper and lower layers by balanced flow to the thrust bearing, and the maximum rotational speed of 74000 rpm was achieved using the asymmetrical seven-lobed bearing. The rotation in this mode is, however, discontinuous due to the collision between the rotor and the journal bearing. It was concluded that a journal bearing with sufficient load capacity is necessary for continuous high speed rotation.

The Effects of Thermal Barrier Coatings on Diesel Engine Emissions

This study has characterized the influence of thermal barrier coatings (TBCs) applied to combustion chamber surfaces on the emissions from an indirect injection (IDI) diesel engine. The TBCs were applied to the piston crown, the cylinder head (fire deck) and the valves of a single cylinder Yanmar TS-180 IDI diesel utility engine. The gaseous and particulate emissions from the baseline (uncoated) and ceramic-coated engine were analyzed to assess the changes in the combustion process caused by the coatings. The results of these analyses show two clear trends during operation of the baseline and ceramic-coated engine. First, comparison of the emissions from the four modes of operation for the baseline (uncoated) engine shows that particulate matter emissions (on a g/kWh basis) are highest at low load-low speed (mode 4) conditions. At low load-low speed conditions (modes 3 and 4), particulate matter decreases substantially with the TBCs present. Second, these observations combined with thermal and morphological analyses of the particulate matter show that the TBCs reduce particulate mass by reducing the volatile organic content of the particulate.

DIFFERENT MODES OF VORTEX SHEDDING: AN OVERVIEW

An enormous research effort has been expended on the flow around bluff bodies for over a century. This paper is an attempt to categorize the observed modes of vortex shedding. First, the low-speed mode caused by the laminar wake instability is juxtaposed to the high-speed mode controlled by the mechanics of vortex formation and shedding. Particular attention is given to the transition from the low-speed to high-speed mode. Second, the discussion is directed to the synchronized vortex shedding, when the transverselly oscillating cylinder takes over the control of frequency of vortex shedding. Again, two modes exist, although the frequency remains unchanged. The phase angle between the force exerted on the cylinder by the fluid and its displacement shows a discontinuous jump in the middle of the synchronization range where a maximum amplitude is reached for the free-oscillating cylinder. This is caused by the sudden 180° change in phase of vortex shedding. Third, yet another synchronized vortex shedding is described that is caused by the streamwise oscillation of a cylinder or when a stationary cylinder is submerged in oscillatory flows. Again, two shedding modes are found by Griffin and co-workers, with a distinct single vortex or two vortices shed during each half-cycle, respectively.

Research on low and high speed hovercraft icebreaking

Operational experience in Canada during the early seventies showed that hovercraft can make very effective icebreakers. In a low speed mode, the hovercraft causes an air cavity to form under the sheet as it rides onto it. This causes a section of the sheet to become unsupported and fail in bending under the action of its own weight. In a high speed mode, the motion of the craft over the sheet sets up large amplitude flexural gravity waves. Research into both modes of operation has been going on at Memorial University of Newfoundland (MUN) since the mid-eighties. This paper summarizes this work. For the low speed case, scaling laws for the resistance to forward motion of two new geometries were developed and confirmed with data obtained in the ice tank at the Institute for Marine Dynamics (IMD) in Newfoundland. For the high speed case, measurements of sheet deflections in the MUN wave tank and the IMD ice tank showed that a critical speed exists for motion over a sheet. At this speed, sheet deflections are limited only by dissipation and nonlinearities. We believe this critical speed is the source of high speed mode hovercraft icebreaking. Key words: hovercraft, icebreakers, air cavity mode, wave mode.

Sudden increase in speed of an actin filament moving on myosin cross-bridges of "mismatched" polarity observed when its leading end begins to interact with cross-bridges of "matched" polarity.

Under in vitro movement assay conditions, actin filaments move about 10 times faster toward, than away from, the center of large bipolar thick filaments of molluscan smooth muscle. Using thick filaments isolated from the anterior byssus retractor muscle of Mytilus edulis, the two speed modes of movement were studied in detail. Some thick filaments crossed over each other on the surface of the assay chamber, allowing actin filaments that moved into the crossover region to transfer to other thick filaments. When an actin filament that had been moving in the low speed mode crossed over to another thick filament and the speed changed to fast, the entire actin filament started to move in the high speed mode at the moment of transfer of its leading end, leaving the trailing part still in contact with the original thick filament. This indicates that myosin cross-bridges interacting in the slow mode do not impose a significant load on the cross-bridges interacting in the fast mode. Assuming the theoretical model of Tawada and Sekimoto [Biophys. J. 59, 343-356 (1991)], we suggest that the magnitude of force developed, as well as the speed of unloaded movement, differs greatly, depending on the orientation of the myosin cross-bridges.

NKK Boundary Layer Wind Tunnel Facilities

NKK completed the second wind tunnel, Boundary Layer Wind Tunnel, in October 1986 to meet more various demands for wind tunnel testing. The working section of the tunnel is 4m wide, 26. 5m long, and 2m high (ceiling adjustable) so that wind tunnel tests such as full model test in turbulent boundary layer which simulates natural wind may be conducted with high accuracy. Wind speed ranges from 0.2 to 23m/s. Even lower wind speed less than 1m/s can be stably controlled in “low-speed mode.”This paper reports the outline of the new tunnel and the results of a series of performance tests.

Stepping Patterns in the Cockroach, Periplaneta Americana

Stepping Patterns in the Cockroach, <i>Periplaneta Americana</i>

Transition in size and number of emitting sites with increase in arc speed over a copper cathode

A recent scanning-electron-microscope study of the damage caused to copper cathodes with a 100 nm oxide film by low-current static arcs of 3.8 ns to 40μs duration in atmospheric air has revealed unexpectedly low emittingsite lifetimes of only about 4.5 ns. Scanning electron microscopy has now been applied to arcs of 12–68 A which are moving (due to a transverse magnetic field), at speeds between 19 and 241 m/s, along a copper cathode with an oxide film of 44 nm or 100 nm thickness. The paper shows that two emitting-site modes are possible for a 44 nm oxide film. The first, which exists for speeds up to a transition range of 80–120 m/s, is shown to be similar in crater size, crater density and in the product of site current and lifetime to the results obtained for static arcs, and the areas of oxide stripped for the two cases can be related. The other mode, which occurs at speeds above this transition range, does not cause stripping of the oxide, and exhibits craters of ten times the previous diameter which are lower in surface density by between 4 and 5 orders of magnitude. The site lifetimes for this mode are much longer than for the low-speed mode where oxide stripping occurs, so that electroforming rather than switching may have taken place.

Proprotor Short-Haul Aircraft-STOL and VTOL

This Paper examines the characteristics of a series of aircraft for the short-haul market. The low disk-loading propeller/rotor is applied to a prdpeller-STOL (short takeoff and landing) transport, a fan jet-STOL transport, a tilt rotor-VTOL (vertical takeoff and landing) transport, and a fan jet-VTOL transport. The resulting aircraft concepts have an efficient low-speed, lift-propulsion system, and can operate with low noise and air pollution from metropolitan V/STOL airports. This paper concentrates on the first two STOL configurations. For low and medium disk-loading STOL aircraft, the gimbal propeller Has important operational advantages compared to the rigid propeller. At takeoff, longitudinal cyclic pitch can be used to produce an upward force to reduce tail download requirements. For takeoff and landing in severe crosswinds, significant side force can be produced by means of lateral cyclic pitch. In cruise, the gimbal propellers give a significantly better ride than rigid propellers. In the approach, longitudinal cyclic pitch can control glide-slope height precisely. A STOL transport with a cruise speed of 400-500 knots (wing loading near 75 psf) could use the deflected slip-stream concept and medium disk-loading (30 psf), folding propeller/rotors (Frontispiece). Propulsion-system power requirements in both the cruise and low-speed mode would be supplied by convertible fan-shaft engines. This Paper shows the power balance between a twin fan-jet cruise requirement of 475 kt and an engine-out critical maneuver requirement at 60 knots.