Microfabricated centrifugal pump driven by an integrated synchronous micromotor

This paper presents the development of a new design of the microfabricated centrifugal force pump. The pumping concept is based on running an impeller (a rotor including permanent magnets carrying straight and backward blades) within an integrated synchronous motor, which can be operated at different rotational speeds to pump water. The impeller is 5.5 mm in diameter, and is 1.5 mm in height. This micropump with 7-straight-blade impeller can operate smoothly up to a rotational speed of 9000 rpm. It can deliver a non-pulsating maximum flow rate of up to 12 ml/min and allows water to be pumped up to a 24 cm water head. Additionally, the micropump with the backward-blade-impeller pump delivered a flow rate of up to 14.3 ml/min. at a rotational speed of 11,400 rpm with no back pressure. The micropump was patterned using a series of microfabrication processes including sputtering, photolithography and electroplating within a clean room. Such a pump can be integrated into a system of a compact size and can provide a wide range of flow rates. It could also be a promising device for use within biological and micro biomedical fields. To our knowledge, this is the smallest centrifugal pump in the world with an integrated electromagnetic synchronous motor that offers such high flow rates.

     

Development of a continuous injection direct rolling imprint system for microstructure thin-plate

A prototype of a continuous injection direct rolling (CIDR) imprint system was developed and applied to CIDR tests to evaluate its feasibility for the large-area replication of an optical micro device. The developed system adopts the theories of injection compression and thermal imprinting and presents the capacity to fabricate a 200 mm-wide and over 10 m-long PMMA plate and to replicate ultra-precision structures on its surface at a rolling speed range of 1.1–11.5 mm/s. Under the given CIDR conditions (injection temperature, 280 °C; injection pressure, 6 MPa; rolling force, 13 MPa; roller temperature, 85 °C), complete fabricating of a 0.7 mm-thick Polymethyl methacrylate (PMMA) plate with 17.3 μm-deep and 35 μm-wide V-groove microstructures was achieved at a rolling speed of 3.4 mm/s. Finally, a light guide plate for a backlight panel was fabricated by CIDR. The light transmittance of this plate reached 90.8 %, the maximum birefringence was ~99 nm and its average haze was 0.51 %.

     

Intelligent Control of High-Speed Turning in a Quadruped

Understanding and implementing the control mechanisms that animals use to robustly negotiate a variety of terrains at high speed remains an unsolved problem. Previous research has resulted in control of quadruped running over a range of low speeds or narrowly around a single high speed. Control over a range of both low and high speeds is difficult because a quadruped system is significantly more responsive at high speeds than at low speeds, and because the proportional-derivative style controllers used by many of the previous researchers are only effective locally around the single speed and turning rate at which the controller was tuned. This work presents a fuzzy control strategy that manages the complex coupling between the multiple system inputs and outputs to successfully execute high-speed turns over a range of speeds and turning rates. The resulting control system stabilizes a 3D quadruped trot up to 4 m/s and turning up to 30 deg/s, on a quadruped system with articulated legs and practical leg mass properties in a simulation environment with realistic friction coefficients and system losses.     

Automatic tuning of iterative computation on heterogeneous multiprocessors with ADITHE

This work studies the problem of balancing the workload of iterative algorithms on heterogeneous multiprocessors. An approach, called ADITHE, is proposed and evaluated. Its main features are: (1) using a homogeneous distribution of the workload on the heterogeneous system, the speed of every node is estimated during the first iterations of the algorithm; (2) according to the speed of every node, a new workload distribution is carried out; (3) the remaining iterations of the algorithm are executed. The result of this workload redistribution is that the execution times for every iteration at every node are similar and, consequently, the penalties due to synchronization between nodes at every iteration are mostly eliminated. This approach is appropriate for iterative algorithms with similar workload at every iteration, and with a relevant number of iterations. The high portability of ADITHE is guaranteed because the estimation of speed of nodes is included in the execution of the parallel algorithm. There is a wide variety of iterative algorithms related to science and engineering which can take advantage of ADITHE. An example of this kind of algorithms (morphological processing of hyperspectral images) is considered in this work to evaluate its performance when ADITHE is applied. The analysis of the results shows that ADITHE significantly improves the performance of parallel iterative algorithms on heterogeneous platforms.     

Predictive seam tracking with iteratively learned feedforward compensation for high-precision robotic laser welding

In this paper, a novel architecture for robotic seam tracking using an industrial robot and off-the-shelf sensors is proposed to compensate the residual errors that are commonly observed in high-precision robotic laser welding due to the nonlinearity of a seam and the fast path drifts along a robot path. Our experiments demonstrate that the robot system can track both linear and nonlinear long seams at a high speed of 100 mm/s with TCP offset-error within ±0.1 mm using the proposed method.     

Design of embedded TCAM based longest prefix match search engine

The content addressable memory (CAM) based solutions are very useful in network applications due to its high speed parallel search mechanism. This paper presents a novel Ternary CAM (TCAM) based NAND Pseudo CMOS–Longest Prefix Match (NPC–LPM) search engine. The proposed system provides a simple hardware based solution using novel 11T TCAM cell structures and NPC word line technique, for network routers. The experiments were performed on 256 × 128 NPC–LPM system under 0.13 μm technology. The simulation result shows that the proposed design provides low power dissipation of 5.78 mW and high search speed of 315 MSearches/s under 1.3 V supply voltage. The presented NPC–LPM system meets the speed requirement of Optical Carrier (OC) 3072 with line-rate of 160 Gb/s in Ethernet networking and IPv6 protocol. The experimental results also show that the proposed system improves power-performance by 65%.     

A traffic cellular automata model based on road network grids and its spatial and temporal resolution’s influences on simulation

Microscopic Traffic Simulation Model based on Cellular Automata (CA) has become more and more popular since it was firstly introduced by Creamer and Ludwig in 1986. Cellular automata are simpler to implement on computers, provide a simple physical picture of the system and can be easily modified to deal with different aspects of traffic. However, in a traditional traffic CA model, the spatial resolution of CA and temporal resolution of simulation are low. Take TRANSIMS for example. The size of cellular automata is 7.5 m and the time step equals 1 s. In such a case, if a vehicle drives at a speed of 4 cells per s, the speed difference between 95 km/h (3.5 1 7.5 m/s) and 121 km/h (4.4999 1 7.5 m/s) will not be distinguished by simulation models. And the temporal resolution of 1 s makes the system hard to model different drivers’ reaction time, which plays a very important role in vehicular movement models. In this paper, a microscopic traffic cellular automata model based on road network grids is proposed to overcome the low spatial and temporal resolutions of traditional traffic CA models. In our model, spatial resolution can be changed by setting different grid size for lanes and intersections before or during simulation and temporal resolution can be defined according to simulation needs to model different drivers’ reaction time, whereas the vehicular movement models are still traditional CA models. By doing so, the low spatial and temporal resolution of CA model can be overcome and the advantages of using CA to simulate traffic are preserved. The paper also presents analyses of the influences on simulation of different 1D lane grid size, 2D intersection grid size and different combinations of temporal resolution and mean drivers’ reaction time. The analysis results prove the existence of spatial and temporal resolution thresholds in traffic CA models. They also reveal that the size of grids, the combinations of different temporal resolutions and mean drivers’ reaction time do pose influences on the speed of vehicles and lane/intersection occupancy, but do not affect the volume of traffic greatly.     

A two-dimensional nano-positioner: Design,modelling and experiments

In this paper, an X-Y nano-positioner driven by the shear piezoelectric actuators (SPAs) is proposed based on the friction-inertial theory. The nano-positioner can output a two-dimensional motion at a maximum speed of 0.187 mm/s within a 5 mm×5 mm workspace. In order to solve the contradiction between the motion velocity and the motion resolution, the coarse and the fine motion modes are first proposed on the SPAs application. The coarse motion and the fine motion are realized based on the power-function-shaped signal and the combined piecewise-curve signal respectively. The performance of the nano-positioner, e.g. the resolution, the velocity and the fluctuation, are analyzed and discussed based on different driving signals. Compared with other nano-positioners, the proposed system in this paper is superior in respect of compact size, high resolution, high velocity and two switchable motion modes. Furthermore, a prototype system of the proposed nano-positioner has been developed, which is evaluated by using a capacitive sensor based measurement system. Experiment results validate the effectiveness of the proposed methodology that can be employed and extended to a variety of SPA involved systems.     

Special-purpose computer for holography HORN-4 with recurrence algorithm

We designed and built a special-purpose computer for holography, HORN-4 (HOlographic ReconstructioN) using PLD (Programmable Logic Device) technology. HORN computers have a pipeline architecture. We use HORN-4 as an attached processor to enhance the performance of a general-purpose computer when it is used to generate holograms using a “recurrence formulas” algorithm developed by our previous paper. In the HORN-4 system, we designed the pipeline by adopting our “recurrence formulas” algorithm which can calculate the phase on a hologram. As the result, we could integrate the pipeline composed of 21 units into one PLD chip. The units in the pipeline consists of one BPU (Basic Phase Unit) unit and twenty CU (Cascade Unit) units. These CU units can compute twenty light intensities on a hologram plane at one time. By mounting two of the PLD chips on a PCI (Peripheral Component Interconnect) universal board, HORN-4 can calculate holograms at high speed of about 42 Gflops equivalent. The cost of HORN-4 board is about 1700 US dollar. We could obtain 800×600 grids hologram from a 3D-image composed of 415 points in about 0.45 sec with the HORN-4 system.     

Optimization of load carriage at desert environment

The present study was undertaken to assess the effect of different magnitudes of load on physiological responses of soldiers in desert terrain and also to estimate an optimum load that can be carried comfortably at specific walking speed. Nine infantry male soldiers of SHAPE-I standard with age 25.22 ± 1.02 years, height 170.78 ± 0.95 cm and weight 66.56 ± 2.38 Kg volunteered in this study. All participants were marched at speed of 6.13 ± 0.40 Km h⁻¹ in desert terrain with 10.7 Kg (16.07% BW) and 21.4 Kg (32.15% BW) load and without load. Heart rate (HR), respiratory frequency (RF), oxygen consumption (VO₂), minute ventilation (VE), energy expenditure (EE) and relative work load (RWL) were recorded by using K4b² system. During carrying of 10.7 Kg load HR, VO₂, EE, RF, VE and RWL (%VO₂max) were increased 13.88, 18.20, 20.16, 7.86, 19.30 and 23.71% respectively in comparison to no load. Similarly, during 21.4 Kg load, physiological responses viz.; HR, VO₂, EE, RF, VE and RWL (%VO₂max) were increased 24.84, 36.98, 33.68, 21.24, 38.25 and 40.64% respectively in comparison to no load. The observation of this study stated that 6.27 Kg (9.42%BW, 50% RWL), 13.7 Kg (20.58%BW, 60%RWL) and 24.86 Kg (37.35%BW, 75% RWL) can be recommended for 8 h, 2 h and for 30 min respectively.Relevance to industryMost of the countries do not have their own database for load carriage in specific environmental conditions. Result of this study will be helpful to the similar kind of population working under specified conditions.     

Visualizing analysis for weld line forming in micro injection molding by experimental method

In micro injection molding, the melt flow behavior is important for the final product quality. However, the current process monitoring and measurement technology are not adequate enough to provide a direct analysis access. In the presented study, a glass insert mold designed for performing the direct visual analysis for melt flow phenomena in micro injection molding is introduced. The micro tensile specimen with 0.1 × 0.4 mm² (depth × width) cross section dimension is chosen as the objective part. The correlation between processing parameters (injection pressure, injection speed, mold temperature) and flow behavior was investigated and analyzed. The results show that the injection pressure put an obvious effect on the filling speed through micro cavity. Injection speed can influence the filling time dramatically also. Higher mold temperature brings positive influence with the flowing speed, due to the lower viscosity of polymers in higher mold temperature.     

Intercross scanning control with double driver for micro-LED display

This paper proposes a control chip for micro-light emitting diode (μLED) applied on real-time display system. The μLED control system has the video transmitter and the LED display matrix. The transmitter includes interface control, memory management, image format conversion. For LED display unit, we present the intercross scanning, memory management, PWM output controller, gamma correction for LED brightness control. TheμLED display is controlled by the intercross drivers to reduce the flicker and promote the sweeping speed with two FPGA controllers, where two parallel SPI data is adopted. The micro LED components are mounted on a PCB with mass-transfer techniques successfully. The FPGA controller can drive about 10 k light-emitting diodes with 12-bit colors for displaying system with PWM method. The passive-matrix micro LED (PMLED) driving can achieve 384 refresh rates with 50 MHz clocking frequency. The experiments result low flicker achieved, which the SVM index is only 1.5 with a photometer measurement.     

New Hick's law based reaction test App reveals “information processing speed” better identifies high falls risk older people than “simple reaction time”

The world is facing a major challenge on population aging and falls present a substantial health problem among the older population. The study is aimed to develop a reaction test App for assessing cognitive function related fall risks in older people. The developed App was tested on one hundred Korean women, consisting of twenty young healthy adults (age: 22.5 ± 0.6), forty community-dwelling older people with no history of falls (nonfallers; age: 72.5 ± 4.4) and forty matched older people with a history of falls (fallers; age: 71.8 ± 4.8). Simple reaction time and information processing speed of participants while performing the reaction test with the developed App were derived through a log-linear regression between the reaction time and number of equi-probable alternative choices based on Hick's law. Older people showed significantly longer simple reaction time and slower information processing speed than the young group. Even though there was no significant difference between older nonfallers and fallers on the simple reaction time (p = 0.54), the older fallers had significantly slower information processing speeds than older nonfallers (p < 0.001). Further, receiver operating characteristic analysis revealed excellent discriminative ability of information processing speed on classifying fallers and nonfallers, with sensitivity of 85% and specificity of 70%. These findings suggest slow information processing speed from the reaction test is an important risk factor for falling in older people. The developed reaction test App can be a convenient assessment tool for the older individuals and healthcare professionals to test cognitive function related falls risks.     

Real-time hardware acceleration of the trace transform

The trace transform is a novel algorithm that has been shown to be effective in a number of image recognition tasks. It is a generalisation of the Radon transform that has been widely used in image processing for decades. Its generality—allowing multiple functions to be used in the mapping—leads to an algorithm that can be tailored to specific applications. However, its computation complexity has been a barrier to its widespread adoption. By harnessing the heterogeneous resources on a modern FPGA, the algorithm is significantly accelerated. Here, a flexible system is developed that allows for a wide array of functionals to be computed without re-implementing the design. The system is fully scalable, such that the number and complexity of functionals does not affect the speed of the circuit. The heterogeneous resources of the FPGA platform are then used to develop a set of flexible functional blocks that can each implement a number of different mathematical functionals. The combined result of this design is a system that can compute the trace transform on a 256 × 256 pixel image at 26 fps, enabling real-time processing of captured video frames.

Rapid quantification of bio-particles based on image visualisation in a dielectrophoretic microfluidic chip

We studied an imaging-based technique for the rapid quantification of bio-particles in a dielectrophoretic (DEP) microfluidic chip. Label-free particles could be successively sorted and trapped in a continuous flow manner under the applied alternating current (AC) conditions. Both 2 and 3 μm polystyrene beads at a concentration of 1.0 × 10⁷ particles ml⁻¹ could be rapidly quantified within 5 min in our DEP system. Capturing efficiencies higher than 95% could be 2 μm polystyrene beads with a linear flow speed, applied voltage and frequency of 0.89 mm s⁻¹, 20 V_p-p and 5 MHz. Yeast cells (Candida glabrata and Candida albicans) could also be captured even at a lower concentration of 2.5 × 10⁵ cells ml⁻¹. Images of aggregative particles taken from the designed trapping area were further processed based on the intensity of relative greyscale followed by correction of the particle numbers. The imaging-based quantification method showed higher agreement than that of the conventional counting chamber method and proved the stability and feasibility of our AC DEP system.     

The effect of a helmet on cognitive performance is,at worst,marginal: A controlled laboratory study

The present study looked at the effect of a helmet on cognitive performance under demanding conditions, so that small effects would become more detectible. Nineteen participants underwent 30 min of continuous visual vigilance, tracking, and auditory vigilance (VTT + AVT), while seated in a warm environment (27.2 (±0.6) °C, humidity 41 (±1)%, and 0.5 (±0.1) m s⁻¹ wind speed). The participants wore a helmet in one session and no helmet in the other, in random order. Comfort and temperature perception were measured at the end of each session. Helmet-wearing was associated with reduced comfort (p = 0.001) and increased temperature perception (p < 0.001), compared to not wearing a helmet. Just one out of nine cognitive parameters showed a significant effect of helmet-wearing (p = .032), disappearing in a post-hoc comparison. These results resolve previous disparate studies to suggest that, although helmets can be uncomfortable, any effect of wearing a helmet on cognitive performance is at worst marginal.     

High speed detection of potato and clod using an acoustic based intelligent system

Discriminating between potato tubers and clods is the first step in developing an automatic separation system on potato harvesters. In this study, an acoustic-based intelligent system was developed for high speed discriminating between potato tubers and soil clods. About 500 kg mixture of potato tubers and clods were loaded on a belt conveyer and were impacted against a steel plate at four different velocities. The resulting acoustic signals were recorded, processed and potential features were extracted from the analysis of sound signals in both time and frequency domains. A multilayer perceptron neural network with a back propagation algorithm was used for pattern recognition. Altogether, 17 potential discriminating features were selected and fed as input vectors to the artificial neural network models. Optimal network was selected based on mean square error, correct detection rate and correlation coefficient. At the belt velocity of 1 m s^?1, detection accuracy of the presented system was about 97.3% and 97.6% for potatoes and clods, respectively. Increasing the belt velocity resulted in the reduction of detection accuracy and increase in the number of miss classified samples. By using this system, it is expected that a potato harvester may operate at a capacity of 20 ton hr^?1 with the accuracy of about 97%.     

Comparisons of tibial accelerations when walking on a wood composite vs. a concrete mezzanine surface

Mezzanine surfaces can be made from concrete, bar grate, or composite materials. Anecdotal data indicate that mezzanines in distribution centers made from composite materials, due to their increased compliance, may be a more comfortable working surface. Prior research suggested that a measure of tibial shock, peak tibial acceleration, could potentially discriminate the biomechanical differences between these surfaces. The objective of this study was to quantify differences in tibial accelerations as 27 people walked on mezzanines constructed from concrete and a wood composite material. Accelerometers were attached bilaterally to the shins of volunteers, and data were collected as they walked 30.5 m on each surface at their normal walking speed, a faster-than-normal walking speed, and a slower-than-normal walking speed. Peak acceleration values obtained from the leg with the highest values were compared. On average, the peak acceleration values were 5% higher on the concrete mezzanine as compared with the wood composite mezzanine (p = .036). These findings suggest that individuals working on mezzanines in distribution centers constructed from composite surfaces would potentially experience less discomfort associated with long exposure periods on these surfaces.     

Fabrication of microfluidic devices for packaging CMOS MEMS impedance sensors

This work presents a polydimethylsiloxane (PDMS) microfluidic device for packaging CMOS MEMS impedance sensors. The wrinkle electrodes are fabricated on PDMS substrates to ensure a connection between the pads of the sensor and the impedance instrument. The PDMS device can tolerate an injection speed of 27.12 ml/h supplied by a pump. The corresponding pressure is 643.35 Pa. The bonding strength of the device is 32.44 g/mm². In order to demonstrate the feasibility of the device, the short circuit test and impedance measurements for air, de-ionized water, phosphate buffered saline (PBS) at four concentrations (1, 2 × 10⁻⁴, 1 × 10⁻⁴, and 6.7 × 10⁻⁵ M) were performed. The experimental results show that the developed device integrated with a sensor can differentiate various samples.