200-Mb wafer scale memory

A prototype of a new permanent magnet machine is presented in this paper, and its experimental tests fully documented. The motor incorporates the benefits of PM machines, namely the high power density and efficiency, overcoming some of its major disadvantages, such as high cost and limited speed range. Low cost is achieved due to the utilization of simple ceramic PM (ferrite) magnets but the unique flux concentrating magnetic structure allows for the maintenance of a high air gap flux density and consequently high power density. All the active material (coils and magnets) are placed in the stator, so that the rotor structure is very simple like that of the switched reluctance machine (SRM). An extended speed range is obtained thanks to a field coil that can be used to weaken the PM field at high speed or to boost the field at low speed.

Efficiency of area-concentrated searching behaviour in a continuous patchy environment

This paper presents an analytical study of the performance improvements that can be obtained at both high and low speed using multiple steered axles on heavy articulated trucks. At high speed, rollover usually represents a worst case scenario. Therefore we have chosen to evaluate possible steering designs based on their ability to reduce lateral acceleration of the semitrailer center of gravity. This is in contrast to passenger cars where four wheel steering has typically been evaluated based on measures that were thought to be related to driver acceptance. This paper also investigates the effects of steering rear tractor axles on the low speed manoeuvrability of the vehicle. Steering algorithms for the rear tractor tyres were evaluated using frequency response and simulation of an obstacle avoidance maneuver. Results indicate that at high speeds considerable reductions in trailer lateral acceleration can be obtained during transient manoeuvres. At low speeds, steering of the rear axles demonstrated improvements in manoeuvrability. More work is needed to determine if drivers are able to effectively make use of these improvements indicated by the open loop models, and to evaluate the practicality and cost of implementing these systems (A).

Purpose The purpose of this manuscript was to investigate the effect of high and low speed blood flow restriction versus non-blood flow restriction isokinetic exercise on isometric muscle strength, muscle fatigue, and muscle contraction displacement. Methods The subjects were consisted of ten males without non-specific muscular skeletal disease. They were classified into four training groups: ① high speed(300°/s) without blood flow restriction, ② high speed(300°/s) under blood flow restriction, ③ low speed(90°/s) without blood flow restriction, ④ low speed(90°/s) under blood flow restriction. Before and after the intervention, all of the subjects underwent measurements of isometric quadriceps strength, muscle fatigue, and muscle contraction displacement. Results In regard to isometric quadriceps strength before & after intervention, there was no significant difference between groups. For the lactic acid measurement before & after intervention, there was a signigicant difference between groups(p<.05). Also, there was a significant difference between groups(p<.05) in muscle contraction displacement in terms of Dm but there was no significant difference between groups in terms of Tc Conclusions Isokinetic exercise with blood flow restriction had effects on lactic acid and muscle contraction displacement.

Dry sliding wear behaviors of La 2O 3–WSi 2–MoSi 2 composite against alloy steel

Pavement surface texture evaluation is mainly analyzed based on elevation data in previous research, and attention also need to be paid to wavelength information. Furthermore, a well-established relationship model between surface texture and skid resistance for real road sections still needs further investigation to help provide useful information on appropriate maintenance time considering skid resistance attenuation. In this research, the macro-texture of asphalt pavement was evaluated from different aspects, including elevation, wavelength information, and geometry, and the relationship models between the macro-texture and skid resistance (at both low and high speeds) were established and compared using the multiple linear regression (MLR) and back propagation (BP) neural network to recommend a suitable one. In order to achieve this, this study monitored anti-skidding performance and the macro-texture of six road sections for 18 months. Firstly, the Dynamic Friction Coefficient (DFC) test and core drilling were conducted on site at three different service times. Additionally, a laboratory accelerated loading test was carried out on specimens prepared by similar material composition to one of the road sections, and the British Pendulum Number (BPN) was tested after different passes of loading. Secondly, 3D laser scanning was carried out on core samples from road sections and laboratory specimens after different passes of loading. The correlation degree between macro-texture indexes and anti-skidding performance was analyzed with the grey correlation entropy analysis method. Finally, the relationship models between the anti-skidding performance at high and low speeds and macro-texture were established based on the MLR and BP neural network. The results indicate that the macro-texture indexes calculated based on elevation data to characterize vertical irregularities have a good correlation with the skid resistance despite the different service times and pavement types. Compared with the BP neural network model, the MLR model has low correlation and noticeable error. The relationship model between F60 (DFC at the speed of 60 km/h) and macro-texture could be well established by the BP neural network. In addition, the relationship between F20, BPN, and pavement surface macro-texture is poor, making it impossible to establish a model with good correlation. Generally, it is recommended to use the BP neural network to establish the relationship model between macro-texture and skid resistance.

Achieving higher operation speeds safely and comfortably is yet a significant challenge in the railway industry. The rail irregularities and wheel-rail interactions in a train running at high speeds may result in large-amplitude vibration in the train’s car body and affect passengers by reducing ride comfort. The train suspension systems have a crucial role in reducing the vibration and improving ride comfort to an acceptable level. In this context, an exclusive semi-active magneto-rheological (MR) damper with a favorable dynamic range was designed and fabricated. The MR dampers were installed in a high-speed train’s secondary lateral suspension system in replacement of original passive hydraulic dampers, with intent to mitigate vibration of the car body and keep the ride comfort in a proper level at low and high running speeds. A unique full-scale experimental investigation on the high-speed train equipped with MR dampers was carried out to evaluate the MR damper functionality in a real operating situation. The full-scale roller experiments were conducted in a vast range of speeds from 80 to 350 km/hr. At each speed, different currents were applied to the MR dampers. The car body dynamic responses were collected to evaluate the ride quality of the train. Ride comfort indices under various train operating conditions are calculated through Sperling and UIC513 rules. This study reveals that the designed MR dampers effectively reduce the car body’s rolling motion. According to Sperling ride comfort index, the car body vibration was “clearly noticeable” at some running speeds when adopting the MR dampers, but it was not unpleasant. Besides, a “very good comfort” was achieved according to the UIC513 criterion. Also, no train instability was whatsoever observed at high speeds. This experimental investigation bears out the capability of the devised MR damper to achieve desirable ride comfort under high running speeds.

Effects of lubricating oils on the drawability of soft aluminum sheets and on the surface condition of drawn cups were studied using different punch-die clearances. The limiting drawing ratio increases with decreasing the clearance at low drawing speed, decreases at high drawing speed at the clearance +50 to 0%, and takes a maximum value at the clearance -10% by the use of lubricating oils. Lubricating with a mineral oil intensifies the surface damage on drawing and ironing faces of the products formed at low drawing speed, and lubricating with oils containing 10% oleic acid and oxidized oil moderates it. If drawn at high speed using a mineral oil, traces of oil-pits are observed on the ironing face of drawn cups and the surface damage is considerably moderated. Metal transfer by adhesion of the worked sheet to the die surface is significant by the use of a mineral oil at clear- ances 50 and 0% at low drawing speed, and is markedly decreased by the use of mineral oil and lubricating oils containing 5% chlorinated paraffin at high drawing speed

For permanent magnet synchronous machines (PMSMs), current harmonics need to be controlled under two kinds of conditions. Under the first condition, the current harmonics caused by the non-sinusoidal back-electromotive force (EMF) and the dead time of inverters should be suppressed. Under the second condition, specific current harmonics should be injected to suppress the torque ripple of motors. Therefore, the accurate control of current harmonics is critical. It has been found that the original multiple reference frame (MRF)-based control algorithm cannot effectively achieve the control of current harmonics at high speeds. For the currents in MRFs, motional EMF was dominant rather than induced EMF at higher speeds. As a result, the original MRF-based control algorithm does not work at high speeds. To solve this problem, this paper proposed a novel MRF-based control algorithm that considers motional EMF. Furthermore, this paper achieved decoupling control of the current harmonics in MRFs for interior PMSMs. With the proposed control algorithm, the current harmonics of interior PMSMs can be controlled at both high and low speeds. Under the influence of non-sinusoidal back EMF and the dead time of the inverter, the effect of current harmonic control was verified on a laboratory test bench.

In this study, microstructural and texture development in the individual weld zone during friction stir welding (FSW) of DP780 steel at similar tool rotation speed (200 rpm) different welding speeds (200 mm/min and 400 mm/min) was investigated. Phase transformations and competition between recovery and recrystallization mechanisms in the distinct weld zones were explored by electron back scattered diffraction (EBSD). More pronounced grain refinement was observed in stir zone (SZ) of sample welded at higher speed (0.62 μm) as compared to lower welding speed (0.51 μm) which is attributed to the enhanced Zener pinning effect at higher welding speeds. Continuous dynamic recrystallization (cDRX) was found to be the dominating recrystallization mechanism in SZ of both welded samples. Orientation distribution function (ODF) based texture investigations of SZ revealed the development of D1 {1¯1¯2}<111> and D2 {112¯}<111> shear components along with the cube {001}<100> texture. The lower texture intensities witnessed in SZ of higher welding speed sample was due to the accelerated recrystallization kinetics at higher welding speeds. The microstructural investigations of thermo-mechanically affected zone (TMAZ) of both welded samples revealed that cDRX was predominant recrystallization mechanism while microshear bands, grain boundary bulging and geometric DRX (gDRX) also assisted the grain refinement. Texture analysis showed the development of D2 {112¯}<111>, J{110}<11¯2> and J¯{1¯1¯0}<1¯12¯> shear components in the TMAZ lower welding speed sample and D1 {1¯1¯2}<111>, D2 {112¯}<111>, J{110}<11¯2> and J¯{1¯1¯0}<1¯12¯> shear components in the TMAZ of higher welding speed sample. Moreover, heat affected zone (HAZ) of both samples showed higher evolution of low angle grain boundaries (LAGBs) indicating that the grains are in the dynamic recovery stage due to lower temperatures and strain.

Unmanned air vehicles or drones have become ubiquitous in our daily lives; they are deployed in performing many tasks from dangerous military missions to simple recreation activities. One air vehicle that has become very popular is the quad-copter driven by four vertical and parallel propellers. Today quad-copters are deployed in many video recording and remote monitoring almost everywhere in the world. One area of interest for quad-copters has been in farming operations; these vehicles are used in farming operations for not only aerial monitoring of soil nitrogen levels but many other farm monitoring operations. One common aspect of most quad-copters is that they are teleoperated by the user, i.e., most of them are not yet fully autonomous. There must be a remote pilot who is connected to the quad-copter by a video link so that he/she can control the maneuver of the vehicle along the intended path. This paper intends to show that a quad-copter can be programmed to run autonomously along a predetermined trajectory by using sliding mode control strategy. Since trajectories in most farms are clearly well known in advance, then they can be programmed into the controller for the quad-copter to autonomously track. The design process involves using the intended trajectory to define the 3-D sliding surface and then letting the quad-copter controller switch about that surface while keeping the vehicle in the target trajectory. The workspace is defined as a 3-D space where the sliding surface is defined by fitting weighted spline functions on the coordinates of the intended trajectory to define the stable sliding surface whose stability lever increases as the vehicle moves towards the target point. Preliminary results compare the trajectories followed by the quad-copter and the intended trajectories by using the mean square deviation. As would be expected, the performance depends heavily on the speed of the quad-copter; higher speeds on sharp curvature are associated with large tracking errors than low speeds on similar curvatures, while the performance on straight line paths was considerably good. This is most likely due to the switching speed because it seems that higher speeds should be associated with higher switching speeds also. The future work intends to study if parameterizing the 3-D splines using speed and time can improve the tracking performance where the switching rate will be made to be proportional to the number of spline functions that define the trajectory irrespective of the speed of the quad-copter.

In this paper, two sets of H7014C/HQ1P4 bearings underwent test for high-speed performance under spray lubrication. The influence rules of rotation speed, pre-tightening force and oil pressure on the bearing temperature rising and host vibration were analyzed by adjusting the bearing rotation speed, axial pre-tightening force as well as oil pressure and measuring bearing temperature and host vibration. It has been found that the bearing temperature rises sharply as the rotation speed increases. At low rotation speed, the pre-tightening force has little influence on the bearing temperature rise, but at high rotation speed, the pre-tightening force should not be too small and can severely affect the bearing temperature rise. Increasing the amount of lubricate oil can reduce the extent of the bearing temperature rise while excessive addition cannot further improve this effect. It has been found that the bearing experiences an excellent high speed performance within the rotation speed of less than 24000r/min. This paper reviews various recent patents on high speed bearing test over the past three years. The list of patents reviewed here is by no means supposed to be complete or extensive but shows nevertheless evolution trends concerning high speed bearing test. An analysis of the reviewed patents repartition that allows conclusion of the expected future developments in this domain. Keywords: Axial pre-tightening force, H7014C/HQ1P4 bearing, high-speed performance test, oil pressure, rotation speed, temperature rise, vibration.

Three electromagnetic current meter probes were deployed in a Canadian gravel‐bed river to obtain simultaneous records at 10 Hz of streamwise (u) and vertical (v) velocity components at three heights above the bed. By looking at the positive and negative signs of the instantaneous fluctuations from the time‐average values of each velocity component at each height, the fluctuating velocity profile of u or v can be treated as a Markov chain with eight states and its statistical properties can be tested against null hypotheses based on the absence of spatial structure. We report results of this novel approach.The most common states of the u profile were those with either higher‐than‐average or lower‐than‐average velocities at all heights; these ‘high speed’ and ‘low speed’ states persisted for up to 3 s. The most common v profiles were all‐upwards or all‐downwards, but these persisted for shorter times than the high speed and low speed u profiles. Analysis of transition probabilities shows statistically significant tendencies for acceleration from the low speed u profile, and change from all‐upwards to all‐downwards v profile, to take place progressively from the uppermost probe downwards, in a sweep‐like way. Deceleration from the high speed to low speed u profile and change from all‐downwards to all‐upwards v profile (burst‐like behaviour) do not show such clear patterns.The results are interpreted in terms of the advection of inverted wedges of relatively high‐momentum fluid, followed by more chaotic structures. A separate set of flow visualization experiments over a mixed gravel bed in a flume supports the presence of advected wedge structures, the decelerating part of the sequence corresponding to irregular ejections of near‐bed fluid.

Low temperature solders are becoming more common in surface mount assembly. Critical SMT components cannot handle the temperatures used for lead-free soldering which typically reaches 240 – 250 °C. Sensitive critical components might be damaged by these high temperatures. High temperatures can also cause warpage and other damage to the assembly. Low temperature solder alloys can be used in many forms including solder paste, wire solder, pre-forms, and bar solder. The main motivation of low temperature soldering is driven by faster technology scaling, reduced energy and emissions. Increasing demand in electronics assembly materials like low temperature solder paste to meet and fulfil the requirements of today’s rapidly changing technology requires major innovation in developing new chemistry platform. A new and innovative chemistry platform needs versatile, multifunction capable chemical molecules as its building blocks to achieve desired solder paste processing properties. To achieve desired properties, a carefully engineered paste flux is used to study high speed printing and reflow properties of low temperature solders. The effect of viscosity and thixotropic index on high speed printability, reflow properties and other warpage defects like non- wet open (NWO) and head in pillow (HIP) were also compared to conventional flux system for low temperature solders. Fine feature printability is evaluated in both low (50mm/sec) and high speed (150mm/sec) printing methods to demonstrate the capability of newly engineered flux system. Further, low temperature solders are finding its importance in fine feature application for advance packaging applications. The newly engineered flux is studied with finer particle size (Type 5) for printability, reflow ability and solder ability along with warpage defects and large area pad voids.

Advances in Detector Systems for Imaging Single Molecule Fluorescence