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Recently, consumers pay close attention to the function of smartphone cameras. The prevalence of smartphone cameras with the high pixels lens causes users to be not satisfied with only the auto-focusing function. The smartphone cameras specifically require the optical image stabilization (OIS) function helping users get sharper and clearer images. Therefore, this paper presents a voice coil type OIS actuator for smartphone cameras with novel electromagnetic design that features the magnets with chamfered edge to reduce the size and the cost of the OIS actuator and improve its power efficiency. And this paper proves its performance through the laboratory-built prototype. The experimental results show that the proposed OIS actuator with the novel electromagnetic design can supply greater and more stable Lorentz force when comparing with the commercial OIS product and the performance of the proposed novel design is robust.

This letter presents an efficient algorithm to detect fetal heart rates based on linear template subtraction (TS) for portable fetal heart rate monitors. After pre-processing, the covariance function windowing is used to eliminate maternal P-waves, maternal T-waves, baseline wander, and to enhance maternal R-waves and fetal R-waves. Next, fetal ECG is extracted by the modified mECG cancellation method which forms a mECG template by projecting an average maternal R-wave as a basis into exponential domains. Finally, fetal R-peaks are detected using a 2-D phase space matrix. The results show that the true positive rate, false discovery rate, and false negative rate of the proposed method are 86.80%, 5.78%, 13.20% respectively, which are better than those of other single-channel fetal ECG template extraction methods. It turns out that the modified template subtraction method has three main advantages. First, the covariance function windowing easily removes baseline wander, maternal P waves and maternal T waves. Second, the modified mECG cancellation model can extract overlapping signals without causing large waveform distortions. Last, both covariance function windowing and the modified mECG cancellation model are efficient and can operate in real time.

In recent years, compact camera modules (CCMs) have been widely used in consumer electrical and electronic products. CCMs with low cost specially are necessary for portable devices. Therefore, the present group recently developed a miniaturized open-loop controlled camera module with low cost for cellphone applications, in which the Lorentz force is balanced by a magnetic restoring force. To enhance the performance of the camera module, this article reports a pattern structure to modify the linearity of the magnetic restoring force. We fabricated a CCM prototype with the dimensions of 8.5 mm × 8.5 mm × 5 mm and demonstrated the usefulness of the pattern structure with the CCM prototype. Its potential applications are foreseeable in portable devices, such as cellphones, web cameras, personal digital assistants and other commercial electronics.

This study proposes a new type of autofocusing microscope. The microscope was combined with a polarized beam-splitting system and an image-processing program to overcome the complex signals generated when focusing on a transparent boundary layer. The polarized beam-splitting system divides a source laser beam into four parallel beams using a birefringent crystal. It also uses an axicon lens to focus individually on different positions of the sample surface when light is incident on the objective lens to observe multiple-spot defocusing information simultaneously. The transparent boundary layer exhibits intricate signals when a sensor detects laser spots. Therefore, an image-processing program is proposed to filter unnecessary signals for calculating the evaluation function and driving the motor, which enables a focused view of the test sample to be attained conveniently. To prove the feasibility of the proposed autofocusing microscope, a frame was developed using a simulation software for observing the initial characteristics of the microscope and for conducting a qualitative analysis. Moreover, the image-processing effect on the sample was tested to determine whether the aim of the study was achieved. The experimental results matched suitably with the simulation results, which indicates that the proposed autofocusing microscope can solve the problem caused by the transparent boundary layer and can achieve a high focusing accuracy within a short focusing time.

Consumers pay most attention to the camera function of smartphones. Thus, manufacturers focus on improving the capabilities of camera modules to deliver clearer and sharper images to consumers. Today, camera modules with auto focusing (AF) and optical image stabilization (OIS) functions are standard in the industry. Specifically, OIS is of the linear movement and rotational movement types. In contrast to the rotational movement type, the commonly used linear movement type cannot compensate for rotational error. Therefore, this paper proposes a novel voice coil motor (VCM) actuator that can supply a 5 degree of freedom (DOF)–compensation that consists of three linear movements and two rotational movements for smartphone camera modules. This novel VCM actuator with 5-DOF compensation is realized using an innovative electromagnetic structure. This paper further verifies the properties of the proposed VCM actuator with a laboratory-built prototype. The experimental results verify the robust properties and feasibility of the proposed VCM actuator.

This paper proposes a new kind of non-contact optical measurement system, which combines with a polygon mirror and a conical lens to achieve the purpose of simultaneously measuring six-degree-of-freedom (6 DOF) geometric errors for a rotary axis of a machine tool. At the beginning, we used the Zemax software to construct the proposed optical structure and observe the change of light spots on the detectors. Then, we built the proposed optical structure on the Matlab software by using the skew-ray tracing method, which used to present the actual condition of light spot change and compare with the simulation results. Then, we designed the appropriate fixtures to place the system structure on a rotary axis in a laboratory environment. After completing the laboratory-built prototype, we analyzed the effects of different geometric errors on the detectors at different angular positions of a rotary axis of a machine tool. The proposed measurement system simultaneously measured 6 DOF geometric errors of the rotary axis, and the experimental results were compared with those of two dial gauges by using the measurement method of ISO 230–7. The experimental results show that the maximum deviation ranges of the radial motion error in X axis, the radial motion error in Y axis, the tilt motion error around X, and the tilt motion error around Y are ±4.7 µm, ±6.0 µm, ±3.6 arcsec, and ±8.1 arcsec, respectively.

This paper proposes a system utilizing a Renishaw XL80 positioning error measuring interferometer and sensitivity analysis design to measure six-degree-of-freedom (6 DOF) geometric errors of a machine tool&rsquo, s linear guide. Each error is characterized by high independence with significantly reduced crosstalk, and error calculations are extremely fast and accurate. Initially, the real light path was simulated using Zemax. Then, Matlab&rsquo, s skew ray tracing method was used to perform mathematical modeling and ray matching. Each error&rsquo, s sensitivity to the sensor was then analyzed, and curve fitting was used to simplify and speed up the mathematical model computations. Finally, Solidworks was used to design the set of system modules, bringing the proposed system closer to a product. This system measured actual 6 DOF geometric errors of a machine tool&rsquo, s linear guide, and a comparison is made with the Renishaw XL-80 interferometer measurements. The resulting pitch, yaw, horizontal straightness, and vertical straightness error deviation ranges are &plusmn, 0.5 arcsec, &plusmn, 3.6 arcsec, &plusmn, 2.1 &mu, m, and &plusmn, 2.3 &mu, m, respectively. The maximum repeatability deviations for the measured guide&rsquo, s pitch, yaw, roll, horizontal straightness, vertical straightness, and positioning errors are 0.4 arcsec, 0.2 arcsec, 4.2 arcsec, 1.5 &mu, m, 0.3 &mu, m, and 3 &mu, m, respectively.

This study proposes a novel FSM compensation system for four degrees of freedom (DOF) laser errors compensation, which has the advantage of shorter optical path length, fewer elements and an easier set-up process, meaning that it can be used at different locations. A commercial software, Zemax, is used to evaluate the function of the proposed FSM compensation system and the mathematical modelling of the proposed FSM compensation system is established by using a skew-ray tracing method. Finally, the proposed FSM compensation system is then verified experimentally using a laboratory-built prototype and the result shows that the proposed FSM compensation system achieves the ability to compensate the 4 DOF of the laser source.

This study designs and characterizes a novel optical system for simultaneously measuring the thickness (> 1 mm) and refractive index of a transparent plate with two optical paths. The proposed optical system is based on triangulation methods. In contrast to exiting optical system based on triangulation methods for simultaneous measurements of thickness and refractive index of a transparent plate, the proposed optical system can measure a greater thickness with a simpler structure and lower cost. The two optical paths are combined using a self-written measurement processing algorithm to simultaneously calculate the thickness and refractive index. The principle and measurement methodology of the proposed optical system are analyzed and explained. The performance of the proposed optical system is then verified and evaluated experimentally using a laboratory-built prototype. The experimental results show that the measured thicknesses and refractive indexes for Sample B (the thickness > 1 mm) are in good agreement with those determined by a commercial instrument with the maximum deviation of 0.019% for the thickness d and 0.007% for the refractive index n, respectively.

For the grinding machine tool, the loading effect is a common phenomenon causing grinding wheel wear. This phenomenon will also cause the deterioration of the grinding wheel cutting capability, requiring a large grinding force, and it will increase the vibration and temperature of the machine. Therefore, the identification of influences from the loading effect is an important subject in grinding machines. We can know the status of a machine for manufacturing grinding through its acoustic emission (AE) signal. We hope that it can eventually be applied to the grinding tool machine for the purpose of online monitoring, achieving an AE pre-alarm system for the loading effect, reducing machine manufacturing errors, and improving grinding machine precision.

Recently, compact and high-resolution camera modules with auto-focusing (AF) function have been integrated into cell phones in order to capture sharp photographs. Consumer demands AF camera modules in cell phones to have high performance with low cost. Accordingly, the present study proposes a new electromagnetic design of miniature AF voice coil motor (VCM) actuator with closed-loop control for cell phone camera modules to satisfy the requirements. The structure of the proposed AF VCM actuators was designed by using simulation methods. The performance of the proposed AF VCM actuators was demonstrated by a laboratory-built prototype. The experimental results have shown that the proposed AF VCM actuator has excellent performance with lower power consumption, higher positioning repeatability, and lower cost, when compared to previous AF VCM actuators with open-loop control or closed-loop control.

This paper presents the reduction of noise and vibration concerning the magnetostriction effects for a single-phase power transformer with a large capacity of 200 MVA. Two magnetic core shapes are investigated: 1) D-yoked core and 2) square-yoked core. The D-yoked core is used for the construction of the transformer prototype in this paper. The magnetostriction and the hysteresis loop of the core material are measured for the simulation and analysis of noise and vibration. The transformer prototype is assembled with an external clamping force applied on the core, and the core vibration and sound-level are observed. The transformer operates with a periodic excitation that may induce resonance in the core. To avoid this, a finite-element analysis is used for modal analysis to identify the natural frequencies of the core. A tank is also designed with a sufficiently rigid structure to avoid resonances. The sound-level of the fully assembled transformer prototype is measured, and it is found to have a low-noise level below 65 dB.

For miniature spindle motors design and their applications, the output torque is one of the most important characteristics and it is necessary to improve the output torque of miniature spindle motors in keeping with consumer preferences. Accordingly, this paper is aimed to overcome this problem and propose a novel electromagnetic structure design to improve the output torque of the spindle motor for miniature cooling fans and modern consumer electronic products. In contrast to one phase DC brushless motor with only one axial air gap or radial air gap inside its electromagnetic structure, the proposed one phase DC brushless motor comprises simultaneously one axial air gap and radial air gap inside its electromagnetic structure. This paper utilizes commercial software MagNet to numerically verify the proposed one phase DC brushless motor. The simulation results show that compared to the conventional one phase DC brushless motors with only one axial air gap or radial air gap, the proposed one phase DC brushless motor can improve the output torque obviously. In other words, the novel electromagnetic structure of the proposed one phase DC brushless motor can enhance the operation efficiency. As a result, the results presented in this study show that the proposed one phase DC brushless motor provides potential solution for both existing and emerging miniature spindle motor applications.

In this paper a novel design is proposed to improve the load capacity of fluid dynamic bearing (FDB) for miniature spindle motors and small-form-factor data storage applications. In contrast to conventional miniature FDB with two sets of herringbone grooves on its inner surface, the proposed miniature FDB comprises another one set of herringbone grooves on its outer surface. The proposed miniature FDB is verified numerically utilizing commercial software Advanced Rotating Machinery Dynamics (ARMD). The simulation results show that compared to the conventional miniature FDB, the proposed miniature FDB can obviously improve the load capacity of the bearing system. Overall, the results presented in this study show that the proposed miniature FDB provides another solution for miniature spindle motor applications.

Autofocusing is a critical function in on-line or off-line automated vision inspection in the manufacturing fields. Accordingly, design of high-performance autofocusing microscopes is an important issue. The present group recently developed a novel laser-based autofocusing microscope comprising two optical paths, which provided a large linear autofocusing range and a rapid response with no reduction in the focusing accuracy (Liu et al. in Appl Phys B 109:259–268, 2012). In the present study, the focusing response of the developed autofocusing microscope is further improved by replacing the two optical paths with one tunable optical zoom system. The proposed autofocusing microscope is characterized numerically by means of commercial software ZEMAX simulations and is then verified experimentally using a laboratory-built prototype. The simulation and experimental results show that compared to the developed autofocusing microscope with two optical paths, the proposed autofocusing microscope achieves a rapid focusing response (less than 3.5 s) under the same autofocusing range (±1500 μm) and focusing accuracy (focusing accuracy of ≤1 μm, repeatability of ±1 μm). Consequently, it confirms the proposed autofocusing microscope has potential for automated vision inspection and optical applications.

The force measurement is essential in many engineering areas and our life. Accordingly, this paper proposes a new force sensor, in which the restoring force of the traditional spring is replaced by an axial magnetic attraction force. The performance of the proposed force sensor is characterized numerically by means of MagNet simulations and is then verified experimentally using a laboratory-built prototype. The experimental results show that a linear relation exists between the axial magnetic attraction force and the displacement of the moving part. It also confirms that the proposed force sensor can successfully measure the applied force via the output of the displacement. Due to such characteristics, the potential applications of the proposed force sensor are in the field of autofocusing voice coil motor actuators for cell phone camera modules.

Due to that the load capacity of the conventional herringbone-grooved cylindrical journal bearing (HGJB) decreases significantly with a decreasing dimension, a requirement exists for miniature HGJB with high load capacity in miniaturized spindle motor applications. This paper investigates the design and characterization of a novel HGJB using dual-layer herringbone-grooved patterns for small spindle motors and cooling fans. In contrast to conventional HGJBs, the proposed HGJB contains another set of herringbone-grooved pattern on its outer surface. The performance of the proposed HGJB is characterized numerically using flow field analysis software. Results show that compared to the conventional HGJB presented by the current group in a previous study, the proposed HGJB can improve the load capacity by 53.7% of the previous value.

This paper presents a miniature autofocus (AF) voice coil motor (VCM) actuator with retaining force in a restricted space that can be applied in an optical AF apparatus. A position encoder consisting of a permanent magnet (PM) and a Hall-effect sensor is used to detect magnetic signals; the displacement of the AF VCM actuator can be obtained from the encoder, thus enabling closed-loop control. The proposed miniature AF VCM actuator consists of a high-permeability magnetoconductive plate and a PM on another side to generate a retaining force when the exciting current is switched off. Using a 3-D finite-element analysis simulation and the Maxwell stress tensor method, the electromagnetic Lorentz force within a movable displacement was determined to be ~16 mN. Blur caused by variable force and load disturbance was observed in images captured during AF operation. This adaptive fuzzy proportional-integral-derivative (PID) control approach compensates for the nonuniform friction, disturbance variation, and even load changes of the movable part of the AF VCM actuator that occur when a subject is photographed in various positions. The adaption mechanism reduced control effort, despite the variable force and load disturbance, and exhibited fast dynamic performance and minimal steady-state error.

Autofocusing is a critical operation in automated microscopy applications in the automated vision inspection, measurement and manufacturing fields. The present group recently developed a novel optics-based autofocusing microscope incorporating two achromatic lenses, which provided a large linear autofocusing range, a rapid response, and a high focusing accuracy (Liu et al. in Appl Phys B 109:259–268, 2012). In the present study, the focusing accuracy of the microscope is further improved by replacing the two achromatic lenses with two cylindrical lens assemblies. The autofocusing performance of the modified microscope is characterized numerically by means of ZEMAX simulations and is then verified experimentally using a laboratory-built prototype. The experimental results confirm that compared with the original microscope with achromatic lenses, the modified microscope achieves a greater focusing accuracy (focusing accuracy of ≤1 μm, repeatability of ±1 μm).

Hydrodynamic bearings (HDBs) have been used for data storage applications because of low friction and shock resistance. However, load capacity of HDB is substantially reduced with a decreasing dimension. Few studies have investigated the behavior of the HDB with its inner diameter smaller than Ø = 2 mm. Therefore, the aim of this study was to efficiently analyze the performance of the miniature journal bearings Ø = 0.6 mm with asymmetrical herringbone grooves. To reduce the number of full-factorial experimental design tests, the Taguchi methodology is used to find out the optimal design parameters of the two-step Herringbone-grooved journal bearings.

Drilling is an indispensible machining process for building a load-carrying structure of composite materials. Delamination defect is often produced at the exit of drilling, which threatens the service safety of the structure. There are back-up methods to reduce delamination when drilling the open flat-plate composite structure, but none for drilling into the curved-surface or hollow-shape structures. This study describes an innovative method using electromagnet and the deformable inexpensive colloid mixed with iron powder to produce magnetic back-up force at drilling exit to suppress delamination in industrial tube parts. The delamination extent can be reduced by 60–80%. The optimal volume ratio of powder-to-colloid is found 1:3.

This paper investigates the design and characterization of a miniature fluid dynamic bearing using novel multi-step elliptical grooves for small-form-factor data storage applications and miniature fan motors. In contrast to conventional herringbone-grooved cylindrical journal bearings (HGJBs), the proposed journal bearing contains a single set of multi-step elliptical grooves (EGJB). The performance of the proposed multi-step EGJB is characterized numerically using proprietary flow field analysis software. In addition, to reduce the number of optimal full-factorial experimental design tests (323), the Taguchi parameter design methodology is used to find out the optimal design parameters of the multi-step EGJB. Results show that compared to the conventional HGJB presented by the current group in a previous study, the proposed multi-step EGJB improves the load capacity. Consequently, the proposed motor represents another solution for both existing and emerging miniaturized spindle motor applications.

Radon volatilization mechanism into the gas phase was hypothesized to explain the anomalous declines in groundwater radon precursory to three major earthquakes – (1) 2003 M W = 6.8 Chengkung, (2) 2006 M W = 6.1 Taitung, and (3) 2008 M W = 5.4 Antung in Taiwan. The epicenters were located 24 km, 52 km, and 13 km from the Antung radon-monitoring well D1, respectively. To verify the mechanism of in situ volatilization, we monitored groundwater-dissolved ethane in addition to radon and methane at well D1 in the Antung hot spring since November 30, 2010. The mechanism of in situ radon volatilization has been corroborated by the simultaneous concentration declines in groundwater-dissolved radon, methane, and ethane precursory to the 2011 M W 5.0 Chimei earthquake. The epicenter was located 32 km from the Antung radon-monitoring well D1. Observations at the Antung hot spring also suggest that radon is the best-choice tracer among the groundwater-dissolved gases for strain changes in the crust preceding an earthquake. On the southern segment of the Chihshang fault, the observed radon minima decrease as the earthquake magnitude increases.

Micro-cracks are a major cause of wafer breakage in the solar wafer manufacturing process. Furthermore, the existence of micro-cracks may lead to electrical failure in the post-fabrication inspection of solar cells and solar modules. Thus, the reliable detection of micro-cracks is an important concern in the photovoltaic industry. Accordingly, the present study proposes a novel micro-crack inspection system comprising a near infrared light source, a CCD camera and a tunable exposure unit. In the proposed system, the intensity of the light transmitted through the wafer is sensed by a photodetector and the exposure time of the CCD camera is tuned accordingly in order to maximize the contrast of the CCD image; thereby improving the performance of the crack detection process. The experimental results show that the proposed system enables the reliable detection of micro-cracks in solar wafers with a thickness of up to 240 μm within 1 s. In other words, the system provides an ideal solution for on-line micro-crack inspection applications in the photovoltaic industry.

This work proposes a novel approach to analyze the stability characteristics for the dynamic coefficients of a herringbone- grooved journal bearing. Based on the perturbation method at the equilibrium position of a journal bearing, this study expresses the variation of critical mass as the derivation of eight dynamic coefficients: four stiffness and four damping coefficients. Since the relationship between the critical mass and the eight dynamic coefficients is very complicated, it is difficult to judge the influence in previous studies of an individual dynamic coefficient on stability. The method presented in this paper can investigate quantitatively which dynamic coefficients dominate stability. The results show that the coefficients Kxx and Kyx increase and improve the stability as the eccentricity ratio increases. As the groove geometry changes, the coefficients governing stability depend on the parameters of groove geometry: groove depth, groove width, and groove angle. When the groove angle changes, variations in Kxy always exert negative influences on stability. When the groove depth or the groove width increases, the change in Dyy exerts a significant negative influence on stability. With an increase in the groove angle or groove pattern, the negative effect of Dyy on the bearing decreases. Accordingly, the influence of variations in the groove depth is similar to that of variations in the groove width.

Due to consumer preference for products with ever higher performance, a requirement exists for precise autofocusing microscope systems to perform the inspection process in automated mass production lines. Accordingly, the present study proposes a laser-based microscope system in which a precise autofocusing capability is achieved using a position feedback signal based on the distance L between the geometrical center (X c , Y c ) of the image captured by the CCD sensor and the centroid (x centroid , y centroid ) of the image. The experimental results show that the proposed system has a positioning accuracy of 2.2 μm and a response time of 1 s given a working range of ±200 μm. The autofocusing performance of the proposed system is thus better than that of a conventional centroid-based system, which typically achieves a positioning accuracy of around 5.2 μm.

This study designs and characterizes a novel precise optics-based autofocusing microscope with both the large linear autofocusing range and the rapid response. In contrast to conventional optics-based autofocusing microscopes with centroid method, the proposed microscope comprises two optical paths, namely one optical path which provides a short linear autofocusing range but an extremely high focusing accuracy and a second optical path which achieves a long linear autofocusing range but a reduced focusing accuracy. The two optical paths are combined using a self-written autofocus-processing algorithm to realize an autofocusing microscope with a large linear autofocusing range, a rapid response, and a high focusing accuracy. The microscope is characterized numerically using commercial software ZEMAX and is then verified experimentally using a laboratory-built prototype. The experimental results show that compared to conventional optics-based autofocusing microscopes with centroid method and a single optical path, the proposed microscope achieves both a longer autofocusing range and a more rapid response with no reduction in the focusing accuracy. Overall, the results presented in this study show that the proposed microscope provides an ideal solution for automatic optical inspection and industrial applications.

Cardiovascular disease remains the main cause of death, and great efforts are spent on the design of ECG (electrocardiogram) body sensors these years. Essential components such as analog frontend and wireless transceivers have been integrated on a compact IC with micro-Watt power consumption. To provide timely warning against the fatal vascular signs, based on the Chaotic Phase Space Differential (CPSD) algorithm, heterogeneous VLSI processors are implemented and integrated to extract the abnormal ECG characteristics for VF (Ventricular Fibrillation), VT (Ventricular Tachycardia) and PVC (Premature Ventricular Contraction). The on-sensor processing reduces 98.0% power of wireless data transmission for raw ECG signals. The application specific processor is designed to accelerate CPSD algorithm with 1.7μW power while the OpenRISC is integrated to provide the system flexibility. The architecture is realized on the FPGA platform to demonstrate the detection of the abnormal ECG signals in realtime.

Pressure buildup tests are often used to determine the reservoir permeability and skin factor to quantify formation damage. However, no quantitative method is currently available for calculating the reduced permeability of the skin zone. With the help of radon measurements during the flow period preceding the buildup test, it is possible to calculate both the radius and the altered permeability in the damaged zone based on a radial composite model.

When designing an auto-focusing actuator for use in cell phone cameras, it is important to maximize the positioning repeatability while simultaneously minimizing the device size, the power consumption, the response time, and the dynamic tilt angle. In a previous study (Liu and Lin, Opt. Express, vol. 17, pp. 9754-9763, 2009), the current group designed a miniature auto-focusing voice coil motor (VCM) actuator in which the lens was held in position using a magnetoconductive plate and a closed-loop control mechanism. The aim of this study is to characterize the performance of this device using an experimental approach. The results show that the proposed actuator has a high positioning repeatability, a low dynamic tilt angle, a rapid response, and a low power consumption.

The Modulation Transfer Function (MTF) is a measure of an optical system’s ability to transfer contrast from the specimen to the image plane at a specific resolution. It can be computed either numerically by geometrical optics or measured experimentally by imaging a knife edge or a bar-target pattern of varying spatial frequency. Previously, MTF accuracy was generally affected by the size of the mesh on the image plane. This paper presents a new MTF computation method based on the irradiance model, without counting the number of rays hitting each grid. To verify the method, the MTF in the sagittal and meridional directions of an axis-symmetrical optical system is computed by both the ray-counting and the proposed methods. It is found that the grid size meshed on the image plane significantly affects the MTF of the ray-counting method, sometimes with significantly negative results. The proposed irradiance method is immune to issues of grid size. The CPU computation time for the two methods is approximately the same.

The epithermal neutron beam of the Tsing Hua Open-pool Reactor (THOR) was constructed for the study of boron neutron capture therapy (BNCT). The THOR epithermal neutron beam was mainly composed of thermal neutrons, fast neutrons, and photons. For fast neutrons and photons, the absorbed dose and the relative biological effectiveness (RBE) were used to characterize radiation dose and radiation quality. The short-ranged alpha particles and lithium ions produced from 10 B(n,α) 7 Li reactions in the BNCT required cellular- and micro-dosimetry characterizations. Due to the non-uniform microdistribution of boron in cells, these characterizations should depend on the source–target geometry. In this case, the geometry-dependent specific cellular dose and lineal energy could be used to describe radiation dose and radiation quality. In the present work, cellular- and micro-dosimetry were studied for the THOR epithermal neutron beam. The specific cellular dose and lineal energy were calculated for thermal neutron-induced α-particles and 7 Li-ions with different source–target geometry and various cell sizes. Applying the linear energy dependent-biological weighting function, the geometry-dependent RBE of thermal neutron-induced heavy particles was determined. Finally, the effective RBE of the THOR epithermal neutron beam was estimated for tumors and normal tissues of specified 10 B concentrations. This effective RBE should be multiplied by the total absorbed dose to determine the corresponding biological dose required in the treatment planning.

This study designs and characterizes a novel precise measurement system for simultaneously measuring six-degree-of-freedom geometric motion errors of a long linear stage of a machine tool. The proposed measurement system is based on a method combined with the geometrical optics method and laser interferometer method. In contrast to conventional laser interferometers using only the interferometer method, the proposed measurement system can simultaneously measure six-degree-of-freedom geometric motion errors of a long linear stage with lower cost and faster operational time. The proposed measurement system is characterized numerically using commercial software ZEMAX and mathematical modeling established by using a skew-ray tracing method, a homogeneous transformation matrix, and a first-order Taylor series expansion. The proposed measurement system is then verified experimentally using a laboratory-built prototype. The experimental results show that, compared to conventional laser interferometers, the proposed measurement system better achieves the ability to simultaneously measure six-degree-of-freedom geometric errors of a long linear stage (a traveling range of 250 mm).

This paper presents the design and fabrication of a miniature axial-gap spindle motor for small-form-factor optical storage applications. The motor features a fluid dynamic bearing (FDB) and is characterized by a high mechanical rigidity, excellent dynamic characteristics, and a zero cogging torque. The performance of this FDB motor is evaluated experimentally using a laboratory-built prototype. The results show that the motor has an excellent dynamic response, a small axial repeatable runout, a small tilt angle, a high rotational speed, and a low operating current. Furthermore, with overall dimensions of just 15.5 × 3.3 mm, the FDB motor is around 80% smaller than that presented by the current group in a previous study (Liu et al., J Magn Magn Mater 304:362–364, 2006). Consequently, the proposed motor represents an ideal solution for both existing and emerging miniaturized portable storage device applications.

When designing an auto-focusing actuator for use in cell phone cameras, it is essential to minimize the device size, maximize the positioning repeatability, and minimize the power consumption. In a previous study, we presented a miniature auto-focusing voice coil motor (VCM) actuator for cell phone camera applications in which the lens was precisely positioned by a closed-loop feedback signal generated by a Hall element. Our study characterizes the performance of this device by using an experimental approach. The results show that the proposed actuator is not only smaller than a conventional VCM actuator with an open-loop positioning system, but also has improved positioning repeatability, a more rapid response, and lower power consumption.

In recent times, the need to reduce the profiles of spindle motors in optical data storage devices without sacrificing their performance has become apparent. With the advent of high-density optical disc technology and reduction in the track pitch, spindle motors must have stable performance while tracking on narrow-pitch disks. In this paper, we present the structure and validations of the performance of a newly developed spindle motor (height 6.1 mm) using fluid dynamic bearing (FDB) for portable optical storage devices. The dynamic characteristics of the spindle motor before and after the accelerated life test are investigated experimentally. The noncontact phenomenon of the motor's shaft and FDB is also verified by using a laboratory-built apparatus. It was observed that the decrease in the axial repeatable runout (RRO) of the developed motor was up to 50% of that of the conventional spindle motor. All of the above validations prove that the developed FDB spindle motor has the potential for minimizing RRO, lowering acoustical noise, and improving reliability in portable optical storage devices.

Due to the rapid development of computer science, software, and biomedical engineering, many clinical diagnosis instruments and control system improved accordingly. The minimization and practicality of sensors, as well as the efficiency and stability of computers make simulation control system in medical instruments become the most important part of developing items. The relevant subject of course, virtual biomedical instrumentations (VBI), which combined with computer science, electrical engineering, and medical science, has become a major developing course in biomedical education. Cross-disciplinary research needs experts in different areas and most cross-disciplinary schools cannot afford it. So it requires integration and cooperation between schools. To address this issue, a graduated course has been designed to provide an opportunity for all professions in each field to discuss and share their resources on an e-learning platform. With the progress of the project, VBI course integrates biomedical education resources from north to south colleges to reduce the request of manpower for cross-disciplinary course of biomedical. In addition, VBI courses initiate the cooperation between academic community and industry.

In the present study, we propose an innovative autofocusing (AF) voice coil motor (VCM) actuator to replace the traditional AF VCM actuators with springs for smart phone camera modules. In the proposed electromagnetic structure, the magnetic pre-compression force between the two guide rods and permanent magnet is used to replace the restoring resilience force of the two springs in the traditional AF VCM actuators. The proposed AF VCM actuator is characterized numerically using the simulation analysis of commercial software Infolytica MagNet and then verified experimentally using a laboratory-built prototype. The experimental results presented in this study show compared to traditional AF VCM actuator, the proposed AF VCM actuator has excellent AF performance to be able to replace the traditional AF VCM actuators. As a result, the proposed device provides a promising solution for smart phone camera modules or industrial applications.Copyright © 2015 by ASME

We recently developed a novel force sensor in which the restoring force of the traditional spring is replaced by an axial magnetic attraction force. In this letter, the linearity of the axial magnetic attraction force–displacement curve is further improved via the addition of two yokes. The performance of the proposed force sensor is numerically characterized by means of simulations and then verified experimentally using a prototype. The results show that the proposed force sensor has a higher linearity of the axial magnetic attraction force–displacement curve (improvement around 1.53%). Moreover, a novel cell phone camera module using the proposed structure is demonstrated with a fast response (≤9 ms) and an improved power efficiency (≤11 mA).

Optical scanners play a key role in many three-dimensional (3D) printing and CAD/CAM applications. However, existing optical scanners are generally designed to provide either a wide scanning area or a high 3D reconstruction accuracy from a lens with a fixed focal length. In the former case, the scanning area is increased at the expense of the reconstruction accuracy, while in the latter case, the reconstruction performance is improved at the expense of a more limited scanning range. In other words, existing optical scanners compromise between the scanning area and the reconstruction accuracy. Accordingly, the present study proposes a new scanning system including a zoom-lens unit, which combines both a wide scanning area and a high 3D reconstruction accuracy. In the proposed approach, the object is scanned initially under a suitable low-magnification setting for the object size (setting 1), resulting in a wide scanning area but a poor reconstruction resolution in complicated regions of the object. The complicated regions of the object are then rescanned under a high-magnification setting (setting 2) in order to improve the accuracy of the original reconstruction results. Finally, the models reconstructed after each scanning pass are combined to obtain the final reconstructed 3D shape of the object. The feasibility of the proposed method is demonstrated experimentally using a laboratory-built prototype. It is shown that the scanner has a high reconstruction accuracy over a large scanning area. In other words, the proposed optical scanner has significant potential for 3D engineering applications.

In the present study, we propose an innovative force gauge to replace the traditional spring sensors. The proposed force gauge is characterized numerically using commercial software Infolytica MagNet simulation analysis and then verified experimentally using a laboratory-built prototype. The results presented in this study show compared to traditional force gauge, the proposed force gauge has good measuring accuracy to replace the traditional spring sensors. As a result, the proposed method provides a promising solution for industrial applications of force measurement.Copyright © 2014 by ASME

Effective methods for speckle reduction are essential in improving the image quality of laser imaging applications. Accordingly, the present study proposes a novel technique for reducing the speckle contrast in laser imaging applications by means of the magneto-optic Kerr effect induced by a rotating magneto-optical (MO) disk. The performance of the proposed method is evaluated experimentally using a laboratory-built prototype model. The experimental results show that the rotating MO disk can reduce the speckle contrast of the captured image by 60% of the previous value. As a result, the proposed method yields an effective improvement in image quality. Overall, the proposed method provides a promising solution for improving the performance of a wide range of laser imaging applications.

Ultrasonic drilling of two-dimensional carbon fiber-reinforced silicon carbide(C/SiC) composites was investigated in this study. The composites were made through a polymer pyrolysis route. X-ray diffraction was adopted to examine the formation of crystalline structure in the matrix of the fabricated composites. Density and porosity, and flexural strength were measured to study the densification efficiency and the mechanical properties, respectively, of the C/SiC composites fabricated under various conditions. The fracture morphologies were also examined by scanning electron microscopy to investigate the fracture behavior of the composites under flexural test. The effects of various parameters of ultrasonic drilling, including abrasives, volume ratio, electric current and down-force, on the material removal rate, hole clearance, edge quality and tool wear are presented and discussed. Optimal operating conditions are identified. In comparison with other feasible machining processes, ultrasonic drilling for this composite material possesses advantages concerning machinability and cost.

This paper presents the effects of the fluid dynamic bearing (FDB) design on the rotational precision of a spindle motor used for drivers requiring higher recording density and data transfer rate. Adopting the numerical flow field analysis on the FDB, the developed motor has robust operating stability in an operational window. The FDB provides the optimal load capacity demonstrated by the experimental results. In addition, the developed motor has excellent axial repeatable run-out performance less than 4 mum