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This papers studies the use of a deep autoencoder to automatically generate dynamics for MIDI (Musical Instrument Digital Interface) files without velocity information. The experimental results show that the proposed approach outperforms existing methods. The subjective tests also show that a MIDI file with velocity values generated by the proposed model sounds more pleasant.

This paper investigates various structures of neural network models and various types of stacked ensembles for singing voice detection. The studied models include convolutional neural networks (CNN), long short term memory (LSTM) model, convolutional LSTM model, and capsule net. The input features to the network models are MFCC (mel-frequency cepstrum coefficients), spectrogram from short-time Fourier transformation, or raw PCM samples. The simulation results show that CNN model with spectrogram inputs yields higher detection accuracy, up to 91.8% for Jamendo dataset. Among the studied stacked ensemble methods, performing voting strategy yields comparable performance as the other methods, but with much lower computational cost. By voting with five models, the accuracy reaches 94.2% for Jamendo dataset.

Mobile payment (MP) is a key tool for establishing a cashless society. To comprehensively examine the critical factors (CFs) that influence the introduction of MP tools by microretailers (MRs) in Taiwan, this study employed the technology–organization–environment model as a theoretical basis. Two multicriteria decision-making tools (i.e., the analytic network process and Vlse Kriterijumska Optimizacija Kompromisno Resenje concept of acceptable advantage) were combined to objectively identify the CFs influencing MRs’ introduction of MP tools. The results indicate that technology is more essential than organization and environment, and the eight identified CFs are security/trust, compatibility, usability, stability, complexity, organizational scale, government support, and information maturity. These CFs and the hybrid method form the basis for the findings and academic contributions of this study. The results serve as incisive and practical guidelines that can help MRs to introduce MP tools, encourage MP use by consumers, and promote the establishment of a cashless society.

The Internet, having a sea of Web applications, is one of the largest data stores for big data analysis. To explore and retrieve the states (pages) from Web applications, Web crawlers have been extensively used. Most crawlers allow the users to define a few crawling directives so as to increase the coverage of states that the crawler can explore. A directive can, for example, assign an input value to a specified input field so that the application is instructed to perform a specific action and visit some special states. Note that, a crawler is supposedly capable of exploring an unknown application. But, given an unknown application, how could the user possibly prepare the required directives in advance? This paper proposes an interactive crawling approach and a crawler called GUIDE to overcome this issue. Instead of passively receiving directives from the user, GUIDE actively asks the user for directives when Web pages containing input fields are found. In addition, GUIDE offers a hierarchical directive structure, allowing the user to define multiple values for the same input field. A case study with three Web applications indicated that (1) interactive directives were very useful for increasing the code coverage of the application being explored—up to 10.3–50.5% of code coverage improvement can be achieved, and (2) using GUIDE is more efficient than using a traditional crawler—given the same amount of time, up to 11% of code coverage improvement can be achieved.

Music is a significant achievement of human activities and culture. Composing music is a complex and challenging task in that many factors, such as scale, key, chord, rhythm, and pitch, and their interactions need to be considered. With the advance of computer technology and artificial intelligence, automatic composition systems emerge and present some promising results. In particular, composing music through evolutionary algorithms has received increasing attention. Although evolutionary approaches are capable of generating compositions that follow music theory, these compositions are easily recognized as machine-made products due to their unpredictability in melodic progression, which is an important factor affecting a human's impression and feeling on a song. This paper aims for an automatic composition system that emulates human intelligence in music composition. Specifically, we propose the phrase imitation-based evolutionary composition (PIEC) to generate compositions by an evolutionary algorithm based on music theory and imitation of the characteristics and melodic progression of human-composed music. The PIEC conducts intraphrase and interphrase rearrangement to imitate the ascending/descending motion of phrases. Furthermore, we design four fitness functions for the PIEC to evolve compositions considering note distribution, interval variance, and music theory. The experimental results show that the proposed PIEC can effectively generate satisfactory compositions with the characteristics of the sample melody. The results also validate the effects of phrase imitation and the four fitness functions on evolutionary composition.

Big data analytics (BDA) becomes a critical phenomenon today that brings revolution to firms in different ways, yet how firms create BDA capability that reflects on firm performance (FPER) in specific industry sectors is not yet clear, with the majority of existing studies taking cross-sector perspectives. This study addresses this gap by focusing on Consumer-Packaged Goods (CPG) & Retail industries in China, drawing on the resource-based view (RBV), and BDA literature. This paper presents the first pilot stage of the study, using a limited sample to derive an initial model of the relationship between BDAC and FPER, hypothesizing that it is partially mediated by the Digital Dynamic Capability (DDC). Apart from laying the foundation for the second stage of a more focused study by validating a measurement model, the analysis of the hypothesized structural model confirms some of the initial hypotheses. The results of our studies will benefit executives who face decision making before and after BDA investment. The insights from this study may help firms avoid unnecessary mistakes, and provides immediate contributions in developing and configuring firm-specific BDAC for enhancing firm performance.

Composing music is an inspired yet challenging task, in that the process involves many considerations such as assigning pitches, determining rhythm, and arranging accompaniment. Algorithmic composition aims to develop algorithms for music composition. Recently, algorithmic composition using artificial intelligence technologies received considerable attention. In particular, computational intelligence is widely used and achieves promising results in the creation of music. This paper attempts to provide a survey on the computational intelligence techniques used in music composition. First, the existing approaches are reviewed in light of the major musical elements considered in composition, to wit, musical form, melody, and accompaniment. Second, the review highlights the components of evolutionary algorithms and neural networks designed for music composition.

A setup of two reflective-type optical sensors for the on-line real-time measurement of straightness and angular errors of a linear stage is presented. The arrangement is similar to that of a linear encoder and can make on-line measurements of stage errors for the analysis of automatic processes as well as real time monitoring. The reflector used as the sensor reference plane was a rectangular piece of commercial silicon wafer. The wafer fixed to the side of the slide was very flat and had good reflective properties. A silicon wafer is much cheaper than a long optically flat mirror of similar precision. The standard deviation of the straightness sensor and the angular error were verified as 0.06 μm and 0.08 arcsec. The accuracy of the two sensors was verified as ±0.25 μm and ±1 arcsec. The two sensors were integrated with a single axis PZT-based stage for real time straightness compensation experiments and the results showed straightness compensation from 3.5 μm down to 0.4 μm.

This paper describes the development of a real time error measuring device for the simultaneous measurement of movement errors in straightness, yaw and roll in a linear machine stage. It was designed specifically for measuring errors in the spatial positioning of meso-scale machine tool stages. The arrangement of the optical path and design of the optical elements make it easy install the device on a linear stage. Roll, yaw and horizontal straightness error motions are sensed using the reflection of a laser beam from a plane mirror. A nonlinear measurement model was derived and simulation analysis showed this could be linearized when the measurement angle error was smaller than 0.05°. The measurement ranges of the proposed system are ±30″ for θ x , ±20″ for θ y and ±30 μm for the z-axis. The measurement precision was verified using a laser interferometer and an electronic level and the accuracy of the angular error and straightness error measurements were found to be in the range of ±0.25″ and ±0.5 μm respectively. The extended measurement uncertainties (95% confidence level) were: 0.46″ for θ x error motion; 0.46″ for θ y error motion; and 0.616 μm for straightness.

At present, the application of the Internet of Things (IoT) is typically centered on a gateway device controlled/manipulated by the user with a mobile App. The peripheral (sensor) devices send the surrounding information (such as temperature, humidity, etc.) to the gateway, which processes and uploads the information to the cloud. When developing the software of an IoT device (a gateway device, App, or peripheral device), it is important to make sure that the device is compatible with the other devices. In particular, before releasing a new version, the tester needs to conduct a thorough testing to ensure that the new version is compatible to all versions of the other devices. This is costly and very time consuming. To overcome this problem, this paper proposes a compatibility testing tool called ICAT (Internet of things CompAtibility Testing tool). ICAT allows a tester to select a target environment, a particular version combination of the IoT devices, and performs compatibility testing for the devices. A test report is offered when the testing is completed. Our experimental results show that using ICAT can improve test coverage and reduce test cost.

Feature Envy is a code smell indicating that a particular class is showing too much interest in the methods/attributes of another class. Several feature-envy detection approaches have been proposed. However, these approaches consider an entire method as a unit for detection. When a method is lengthy, the exact location of the problematic statement may not be immediately obvious, and when a method mixes several kinds of behaviors, these approaches could be easily fooled. This paper proposes a characterization of feature envy and a detection approach. A tool, called FEED (FEature Envy Detector), based on dataflow analysis is developed to perform feature-envy detection. In comparison to previous approaches, the proposed approach offers a better detection granularity and also provides a better detection accuracy.

Crawlers have been used in different aspects for testing Android apps automatically, such as crash testing and test inputs generation. However, the efficiency of crawlers can be a concern as it often takes hours or even days to fully explore a non-trivial app. This paper presents a crawling algorithm called NFS (Nearest unvisited event First Search) that can reduce the number of app restarts in order to improve crawling efficiency. Moreover, NFS can also achieve satisfactory code coverage and generate a GUI state graph for the app under exploration automatically. The experimental results show that in average NFS can be more efficient and can also obtain better code coverage than traditional crawling algorithms.

This paper integrated a laser triangulation probe with a two-dimensional image measurement system to measure the height of an object using the auto-focusing method. In the laser triangulation probe, the laser diode was used as the light source and one-dimensional position sensitive detector was adopted to receive the position of the laser spots to detect the height. The laser triangulation probe was used for small height measurement and the auto-focusing method was used for large height measurement. Two standard gauges with thicknesses of 8mm and 8.5mm were used to verify our proposed method. With height difference of 500μm, the experiment results showed the measuring error was within ±3μm and standard deviation was about 0.1μm.

This paper presents a general mathematical model for NC-machining an APT-LIKE rotating cutter. The design model of cutting-edge and helical groove are also developed by using the principles of differential geometry and kinematics. The analytical solution for the resolution profile of helical groove has also been developed. The results of numerical experiment indicate that the proposed systematic design method by using 2-axis NC machine setup are feasible and reliable.

Along with the widespread use of smartphones, Android has become one of the major platform for multimedia applications (apps). However, due to the fast evolution of Android operating system and the fragmentation of Android devices, it becomes important for an Android multimedia app to be tested on different devices to ensure that the app is compatible with and run well on any of the devices so as to provide consistent user experiences. This paper presents a cloud testing platform (CTP) that allows Android multimedia apps to be tested automatically against a scalable number of physical devices in parallel. Particularly, CTP provides four types of testing to ensure the compatibility of apps from different perspectives. Further, to facilitate identifying the bugs of apps, in addition to test results, CTP also provides the video, screenshots, and performance data corresponding to the tests. The case study shows that CTP can be effective in ensuring the compatibility of Android multimedia apps while saving test time and effort.

This paper describes an optical sensor for the real-time measurement of axial thermal elongation of a machine tool high-speed spindle. A cat's eye optical reflector embedded in the spindle reflects the image of a laser diode beam onto a quadrant photodiode detector. Changes in the position of the reflected laser spot on the photodiode in a detection module allows determination of changes in length of the spindle. The resolution is 50 nm for the low frequency range. The accuracy of this optical sensor is better than 1 μm within the measuring range of ±100 μm and the triple standard deviation is 0.03 μm. The experimental results showed that thermal elongation can be measured and controlled to within 2 μm of elongation and shortening variation within the stated range using an oil cooling system.

With the trend of digital economy, cloud services and its ecosystem have developed and matured. Another fast-growing trend, data Economy and big data, changes the way how cloud services create value. This research aims to explain the evolution of cloud service development during the big data era in the design science perspective. An ecosystem model with three roles is proposed to show the big data ecosystem and the relationships with the development of cloud services. Currently, we use a cloud service case to explain the proposed model and believe that the proposed model can inspire further research on cloud and big data ecosystem.

In keyword-driven testing (KDT) , a keyword represents a sequence of actions (events and assertions) and a test case is constructed by using a sequence of keywords. That is, in a KDT script, a test case depends on a number of keywords, and a keyword depends on some other keywords and GUI components. Such dependency is also known as the coupling between test cases, keywords, and components. This paper studies the question of whether low coupling is an important design principle to KDT Scripts. A coupling measure, called unweighted coupling, is proposed. A case study is conducted to assess the maintainability and readability of KDT scripts with different couplings . The results indicated that, when maintaining KDT scripts, a low-coupling script required, on average, less changes than a high-coupling one. On the other hand, a low-coupling script does not necessarily offer a better readability .

Evolutionary composition has received considerable attention in these years. An automatic composition system based on evolutionary computation is attractive but very challenging because the evaluation function is difficult to design: First, human's evaluation on a composition is subject to personal feeling and preference. Second, different regions form their unique music genres from local customs, lifestyle, or ethnic history. These genres enrich music diversity and human sensation. This study presents an evolutionary composition system to address the above two issues. More specifically, the proposed system adopts general music theory rules as the fundamentals of fitness evaluation, thereby ensuring the basic harmony and consonance. In addition, we explore the specific musical expressions of Flamenco and Argentine Tango, and include their features in the evolutionary composition system to create a fusion. Experimental results show that the generated music is satisfactory and can express the emphases of both Flamenco and Argentine Tango.

Software testing usually accounts for a large proportion of software development time and cost. Thus, it is crucial to improve test efficiency and reduce test cost as much as possible. This paper describes a cloud-based approach to increase test efficiency by partitioning a large test job into multiple tasks and executing the tasks concurrently on different virtual machines (VMs). Several task partitioning and grouping strategies are presented for satisfying test deadline and other test requirement, such as shorter test execution time or less VM rental cost. To evaluate the proposed strategies, a case study was conducted. The results indicate that the proposed approach and strategies can be promising for improving test efficiency and cost-benefit.

An analytical model based on a nonlinear deflection equation and the Reynolds equation is proposed to describe the dynamic behavior of an electrically actuated micro-beam with two piezoelectric layers. The proposed model takes explicit account of the fringing field effect, the axial stress effect, the residual stress effect, and the squeeze-film damping effect between the micro-beam and the lower electrode. The nonlinear governing equation of the micro-beam is solved using a hybrid computational scheme comprising the differential transformation method and the finite difference method. The validity of the analytical model and numerical solution procedure is demonstrated by comparing the result obtained for the pull-in voltage of a micro-beam actuated by a DC voltage only with that presented in the literature. It is shown that the nonlinear dynamic response of the micro-beam can be controlled using a combined driving scheme consisting of both the magnitude and the frequency of the AC actuating voltage and a DC driving voltage. The effects of the AC/DC actuating conditions, micro-beam geometry parameters, and squeeze-film damping force on the center-point displacement of the micro-beam are systematically examined. In addition, the actuating conditions which ensure the stability of the micro-beam are identified by means of phase portraits and Poincare maps. In general, the results show that the analytical model and hybrid numerical scheme provide a feasible means of analyzing the dynamic response of a variety of electrostatically-actuated microstructures.

This study presents and investigates a six-DOF (degrees of freedom) piezoelectric based stage for positioning error compensation. The relationship between the displacement of the piezoelectric actuators and the stage can be computed according to the geometric relationships of the actuators installed. In this study, a feedforward compensator based on the hysteresis model has been designed for compensation and a PI controller was used for positioning. The combination of a feedforward compensator and PI controller gives the stage good positioning and tracking performance. Stage position information is feedback from a six-DOF optical measurement system comprised of three modular two-dimensional measurement devices. Each module employs a quadrant photodiode (QPD), a laser diode, and a lens. The measurement signal is acquired and processed using an FPGA based processor for real time control. The linear and angular positioning resolution is 0.02 μm and 0.1 arcsec, respectively. When the stage is controlled in a closed loop, the positioning errors are in the range of±0.1 μm and±0.5arcsec. The stage is controlled to track a sinusoidal wave with an amplitude of 2.5 μm and a frequency of 5 Hz; tracking errors were within±0.1 μm and±0.2arcsec.

To ensure the correctness of Web applications, the dynamically generated Web pages must be tested. However, this can be impractical as dynamic pages can be infinite depending on user inputs and internal states of Web applications. This paper presents an approach to classify the JSP dynamic pages for reducing the number of pages to be tested. Specifically, the approach identifies the HTML statement slices inside a JSP script and classifies the dynamic pages generated by the script according to the compositions of the HTML statement slices associated with the script's linearly independent paths. With the approach, the JSP dynamic pages containing similar testing artifacts can be classified into the same category. Thus, the number of JSP dynamic pages to be tested can be greatly reduced.

In this study, a thickness and refractive index measuring system for the transparent plate has been proposed. The measuring system is composed of an astigmatic measurement module and a light spot measurement module using a DVD optical pickup, a laser diode and a quadrant photodiode detector. Both of the thickness and refractive index of a transparent plate are converted into the focusing error of DVD pickup based on astigmatic method and the light spot displacements based on snell’s law in our proposed system. The thickness and the refractive index are simultaneously calculated by means of two nonlinear formulas. The accuracy of the proposed system is 99 % verified by a height Gauge and the refractive index by the TF-166.

This study proposes a new type of measurement system for the flatness of ceramic surface. The system proceeds the measurement with the optical pickup head of blue ray. It used the light source emitted from the optical pickup head which reflected by the ceramic surface and the reflective light was received by the photo diodes in the optical pickup head then to be calculated into focusing error signal. Then, we can automatically lock focus and analyze the data on the measurement surface by the program to get the flatness of the ceramic surface. The advantages of this measuring method are that no need to use expensive interference system, easier to set up and operate, the over-all cost of detection devices is low, the size of components is small, and the measurement accuracy can up to sub-micron level. The resolution of this measurement system is up to 20 nm.

As a cloud computing application, virtual desktop service has attracted increasing attention from educational institutes because it allows students to learn outside the confines of specific time and place by granting them access to authorized software which was previously inaccessible off campus. In other words, students can continue their learning by using the authorized software after leaving the campus. Hence, understanding students’ continuance intention to use such kind of service will enhance its prospects in educational institutes. The information systems continuance model was employed in this study to achieve this goal. The research findings of this study revealed that students’ continuance intention is primarily influenced by perceived usefulness; while perceived usefulness is mainly affected by confirmation. It implies that students’ expectation confirmation is the key factor to the success of this service.

Open source software (OSS) has attracted a lot interest among academics and practitioners from mid-1990s. However, there is insufficient attention on healthcare and medical informatics (HMI) of OSS (HMIOSS), most studies on OSS success are either qualitative or exploratory in nature. Hence, to identify the factors that influence HMIOSS success and establish generalize ability, an empirical study measuring HMIOSS success would enable HMIOSS developers and users to improve HMIOSS usage. In this study, we develop a HMIOSS success model from a previous information systems success Model incorporating the characteristics of HMI domain. This research contributes towards advancing theoretical understanding of HMIOSS success as well as offering practitioners for enhancing HMIOSS success.

For eLearning, how to naturally measure the learning attention of students with lower cost devices in an unsupervised learning environment is a crucial issue. Students often far away and out of teachers’ control in above situation which may cause students do not have strong learning motivation and might feel fatigued and inattentive for learning. A real-time and naturally learning attention measure approach can support instructor to better control the learning attention of students in unsupervised learning environment. This paper proposes an integrated approach, named Real-time Learning Attention Feedback System (RLAFS) which could naturally measure learning attention in unsupervised learning environments. The system architecture of RLAFS consists with three layers: first layer is Image preprocessing layer, which is responsible for image processing and motion detection. Second is eyebrow region detection layer, which is focus on the features of face and eyes capturing and positioning. Classifier layer is the third layer, in which integral image, volumetric features and finite-state-machine are used to capture the current state of learning attention of students. Consequently, support vector machine is utilized to classify the level of learning attention. The experiments are conducted in an unsupervised environment, and results showed RLAFS is a promising approach which can naturally measure learning attention and has a significant impact on learning efficient.

In recent years, as there is demand for smart mobile phones with touch panels, the alignment/compensation system of alignment stage with vision servo control has also increased. Due to the fact that the traditional stacked-type stage has cumulative errors of assembly and it is heavy, it has been gradually replaced by the coplanar stage characterized by three actuators on the same plane with three degrees of freedom. The simplest image alignment mode uses two cameras as the equipments for feedback control, and the work piece is placed on the working stage. The work piece is usually engraved/marked. After the cameras capture images and when the position of the mark in the camera is obtained by image processing, the mark can be moved to the designated position in the camera by moving the stage and using alignment algorithm. This study used a coplanar stage with 1 m positioning resolution. Due to the fact that the resolution of the camera is about 3.75 m per pixel, thus a subpixel technology is used, and the linear and angular alignment repeatability of the alignment system can achieve 1 m and 5 arcsec, respectively. The visual servo motion control for alignment motion is completed within 1 second using the coplanar stage.

As Ajax, a widely used web development technique, is able to dynamically construct the structures of DOM elements on the browser side, more and more executions of business logic have been shifted from back-end servers to front-end browsers. Moreover, by means of Ajax technique, updates of Web content can take place asynchronously in the background without requesting the whole web pages from servers so it gains the benefit from reducing the amount of network traffic between browsers and web servers. However, in term of web application testing, the existing approaches, adopting web-browsing paths as test cases, are failed to apply in such web applications. In this paper, we propose a test model for Ajax-based web applications based on a hierarchical state machine. The test model is established from observing the state changes of HTML element's attributes and the events that trigger the changes, and then transformed into state transition test trees. Finally, it generates corresponding test cases composed by triggered events to test the behavior of Ajax-based web applications.

This study applied laser diffraction theory and forward kinematic analysis to propose a mathematical model and a verification system for the four-degree-of-freedom motion errors of a linear transmission mechanism. The mathematical model is derived using the three-dimensional diffraction grating equation and a homogeneous transformation matrix. The verification system consists of a laser diode, a piece of transmission grating, and two quadrant photodiode detectors. This system can measure the straightness errors in the horizontal and vertical directions of a one-dimensional linear moving stage, as well as the angular errors of pitch and yaw of this stage, based on the proposed mathematical model. The experiment correction results for the mathematical model showed that the accuracy of this system in measuring the straightness errors in horizontal and vertical directions within a +/- 50 @mm measurement range is +/- 1 @mm, and the accuracy in measuring the angular errors of pitch and yaw within a +/-50 arc sec measurement range is +/-1 arc sec.

Five-axis CNC machine tools comprise three linear axes and two rotary axes, enabling the fabrication of complex workpieces, such as dies, turbo blades, and cams. Improved measurement methods are continually being researched to increase the accuracy of five-axis CNC machine tools. This paper presents a novel optical calibration system, called non-bar, with no linkage bars. The system comprises a master detector module, a ball lens module, and a signal module. The proposed measurement system was implemented according to ISO/CD 10791-6 to measure A-type, B-type, and C-type five-axis CNC machine tools from three different manufacturers. The results demonstrate that the proposed non-bar measurement scheme provides high accuracy, high reproducibility, and simultaneous multi-axis measurement.

This paper presents an interleaved zero voltage switching ZVS DC/DC converter with high input voltage applications. In order to reduce the voltage stress of MOSFETs, two half-bridge zeta converters are connected in series at high voltage side. Thus, the voltage stress of MOSFETs can be clamped at one-half of input voltage. Asymmetric pulse-width modulation APWM is adopted to control power switches. With the resonant behavior by the leakage inductance of transformer and the output capacitance of MOSFET at the transition interval, MOSFETs can be turned on at ZVS. For each half-bridge zeta converter, two series transformers are connected in series at the primary side and in parallel at the secondary side in order to reduce the current stress of secondary windings for high load current applications. Interleaved PWM scheme is used to control two half-bridge converters in order to reduce the size of output filter inductor and capacitor due to the partial ripple current cancellation. Experimental results, taken from a laboratory prototype rated at 1kW, are presented to demonstrate the converter performance. Copyright © 2012 John Wiley & Sons, Ltd.

A multi-degree-of-freedom laser linear encoder that can simultaneously measure the position, straightness, pitch, roll, and yaw errors of a linear stage is developed. The proposed laser encoder uses the phase and spatial information of diffracted light. When the light is reflected from a grating and diffracts, the relative movement makes the orders of diffracted light have both phase and spatial geometric variations. The proposed encoder design makes the ±1 order diffracted light interfere and outputs pure sine and cosine wave signals for linear displacement. The ±2 order diffracted light spots are received by two quadrant photodiode detectors and analyzed to inversely calculate the other motion errors. The experimental results show that the measurement error is ±0.6 μm for straightness, ±0.8 arcsec for angular error, and ±1.2 μm for linear displacement.

A broadband monolithic image rejection subharmonic mixer using a standard 0.18"m CMOS technology is proposed. This circuit is composed of a band-pass fllter with an intermediate frequency (IF) extraction function that can simplify the block diagram of the image rejection mixer. The entire passive circuit is constructed using a broadside coupling structure to achieve a high level of integration. Based on measured results, the proposed mixer exhibits conversion loss of 15.5{18.5dB at a local oscillator (LO) power of 13dBm, whereas the 3dB bandwidth ranges from 20 to 31GHz (43.1%) with a miniature chip dimension of 0:77 £ 0:81mm 2 . The LO-to-radio frequency (RF), 2LO-to-RF, and RF-to-IF isolation levels are higher than 22.5, 42.9, and 34.5dB, respectively. The best image rejection ratio of 29dBc with 20 - phase compensation at 24.5GHz can be achieved.

A 24 to 44 GHz upconversion broadband subharmonic mixer with a novel isolation-enhanced architecture is presented through a 0.15 $\mu$ m GaAs pHEMT process. Total chip size including probe pads is less than 1.33 $\, \times \,$ 0.82 mm $^{{{2}}}$ . The isolation-enhanced circuit is constructed from two directional couple lines both formed with three microstrip lines. They are used to enhance the isolation between IF/LO-to-RF and LO-to-IF. IF and RF pre-amplifiers are employed to achieve high conversion gain for subharmonic mixing of anti-parallel diode pairs. Based on the unilateral characteristics of an IF pre-amplifier, the LO/RF-to-IF isolations exhibit substantial improvement. From the measured results, the conversion gain of the mixer is 6.0 to 10.5 dB operating at RF frequency of 24 to 44 GHz. The IF-to-RF, LO-to-IF, LO-to-RF, and 2LO-to-RF isolations are 24.5 to 27.1 dB, 32.4 to 39.6 dB, 20.6 to 24.6 dB, and 48.4 to 65 dB, respectively.

In the current trend, Extreme Programing methodology is widely adopted by small and medium-sized projects for dealing with rapidly or indefinite changing requirements. Test-first strategy and code refactoring are the important practices of Extreme Programing for rapid development and quality support. The test-first strategy emphasizes that test cases are designed before system implementation to keep the correctness of artifacts during software development; whereas refactoring is the removal of "bad smell" code for improving quality without changing its semantics. However, the test-first strategy may conflict with code refactoring in the sense that the original test cases may be broken or inefficient for testing programs, which are revised by code refactoring. In general, the developers revise the test cases manually since it is not complicated. However, when the developers perform a pattern-based refactoring to improve the quality, the effort of revising the test cases is much more than that in simple code refactoring. In our observation, a pattern-based refactoring is composed of many simple and atomic code refactorings. If we have the composition relationship and the mapping rules between code refactoring and test case refactoring, we may infer a test case revision guideline in pattern-based refactoring. Based on this idea, in this research, we propose a four-phase approach to guide the construction of the test case refactoring for design patterns. We also introduce our approach by using some well-known design patterns and evaluate its feasibility by means of test coverage.

The effect of rotor excitation voltage on steady-state stability and output power of a doubly fed induction generator (DFIG) is investigated. Wind turbine mechanical torque-speed characteristics, as well as generator electromagnetic torque-speed characteristics, are considered in the derivation of the steady-state stability region for the magnitude and phase angle of the rotor excitation voltage. To evaluate the maximum output power of a DFIG, detailed expressions for stator power, rotor power, stator loss, rotor loss, and electrical power are derived as functions of the generator speed and the magnitude and phase angle of the rotor excitation voltage. The effect of stator resistance on the magnitude and phase angle of the resultant optimal rotor excitation voltage, which gives maximum output power and minimum loss, is examined. Experimental results are given to demonstrate the effectiveness of the theoretical analysis.

This article considers the force control of an active probe for Atomic Force Microscopy (AFM). Firstly, the structure of this active probe is described. For designing the force controller, the model of this active probe was identified. Based on the measured frequency response, two notch filters were used to remove the resonant peak in open-loop frequency response. Then, a PI controller was designed to regulate the force of the probe. This controller was then implemented in a Digital Signal Processor (DSP). Experimental results were given to compare the actual performance of this controller with the conventional PI controller. It is shown that the controller with notch filters reduces the control error considerably and enables faster scan speed at weaker tip-sample interaction forces.

Metal-semiconductor-metal ultraviolet photodetectors on flexible polyethylene terephthalate (PET) substrates with ZnO nanorods have been characterized. The photoresponsity and UV-to-visible rejection ratio of the ZnO nanorod-based sensor were 0.0409 A/W and 282.59, respectively. Compared to a traditional ZnO photodetector without nanorods, the fabricated novel photodetector showed much higher photoresponsity which could strongly depend on oxygen adsorption and desorption in the presence of trap states at the nanorods surface. It can be attributed to high surface-to-volume ratio of ZnO nanorods.

Based on the theory of laser measurement, a novel laser-based system to measure the thread profile of ballscrew has been proposed, which integrates the triangulation laser measuring system and the dual-axis rotary stage. The proposed system is made of the laser-based measuring unit to detect the longitudinal section of the thread profile and the dual-axis rotary stage for the movement of the undetected object. The experimental results show that the parameters of the measurements for the threaded gauge are in the tolerance range. Moreover, the measurement errors of this non-contact measuring technique are analyzed by the comparison between the proposed system and the coordinate measuring machine (CMM) system. The maximum error band of the measurements for the screw and the nut is about 4 and 4.5 μm, respectively.

In this paper, a Dual-Axis Long-Traveling Nano-Positioning Stage (DALTNPS) is presented. In order to extend the traveling and increase the accuracy, the two sorts of stages, a traditional ball-screw stage and a three-degrees-of-freedom (3-DOF) piezo-stage, were composed. The traditional ball-screw stage which is composed of two guide-ways and a ball-screw at each axis is a long-travel stage, and the 3-DOF piezo-stage, which is composed of three piezoelectric actuators and four translation–rotation mechanisms, is a high precision stage. In addition, a 3-DOF measuring system and a PID controller are composed of a 3-DOF closed-loop controller and applied to implement the DALTNPS. The measuring system which is composed of two laser interferometers and two plane mirrors is a 3-DOF optical measuring system. Thus, the position at the x and y axes and the rotation around the z axis can be obtained and they are the responses of DALTNPS. Finally, the experiment results evidence that the DALTNPS is characterized by long-travel, high linear accuracy, high rotation accuracy, high contouring accuracy and high motion speed.

A self-tuning proportional-integral (PI) controller in which the controller gains are adapted using the particle swarm optimization (PSO) technique is proposed for a static synchronous compensator (STATCOM). An efficient formula for the estimation of system load impedance using real-time measurements is derived. Based on the estimated system load, a PSO algorithm, which takes the best particle gains, the best global gains, and previous change of gains into account, is employed to reach the desired controller gains. To demonstrate the effectiveness of the proposed PSO self-tuning PI controller for a STATCOM, experimental results for a system under different loading conditions are presented. Results from the self-tuning PI controller are compared with those from the fixed-gain PI controllers.

In this paper, a new optical 3‐dimensional vibrometer is presented. This system is composed of two orthogonally set up corner cubes (CC), a collimated laser source, two quadrant detectors (QD) and three beam‐splitters (BS). The corner cubes are designed to be fixed to the vibrating object and reflect the laser source onto the quadrant detectors. Due to the optical characteristics of the corner cubes, the measuring results of the QD can be magnified twice and it is not affected by micrometer‐angle. So, the three‐dimensional vibration amplitude can be obtained. The resolution is about 50 nm. This system is characterized by three‐dimensional measurement, high resolution, low cost, simple set up and wide bandwidth.

A novel subharmonically pumped resistive mixer (SH- PRM) with a core chip dimension of 0:64 £ 0:65mm 2 is fabri- cated through a standard 0.18"m CMOS process. An impedance- transforming active quasi-circulator is monolithically integrated with an nMOS fleld-efiect transistor (FET) to perform up-converter mix- ing while simultaneously enhancing all port isolation through a broad- band operation. The design analysis of impedance-transforming ac- tive quasi-circulator is also presented for matching between circulator and resistive transistor. As shown in the measured results, the mixer exhibits a 9{14.5dB conversion loss. All port-to-port isolations bet- ter than 16.5dB over a radio frequency (RF) of 10{20GHz can be achieved.

This paper describes the successful development of a middle-range six-degrees-of-freedom stage, using the features of a flexible structure. The system includes two parts: a middle-range positioning X— Y stage and a four-degrees-of-freedom stage. The flexible structure of the four-degrees-of-freedom stage is built from two kinds of flexible bodies: circular hinges and a new two-degrees-of-freedom flexible body. The four-degrees-of-freedom stage was designed to compensate movement errors including linear displacement, pitch, and roll errors. The linear displacement reaches 20 mm along the X-axis, 20 mm along the Y-axis, and 5 μm along the Z-axis. The rotation angle around the X-axis (θ x), Y-axis (θ y), and Z-axis (θ z) were all 10 arcsec. A novel six-degrees-of-freedom measuring system was also designed. Precision feedback control is demonstrated in a series of experiments performed using the proposed measurement system.

At present, the accuracy of precision manufacture is most affected by straightness errors, so the measurement and compensation of these errors are very important. In the current paper, three measurement systems for straightness are presented; they are characterized by simple set-up, online measuring, low cost, and sub-micrometre accuracy achieving 0.2 μm. Experimental results show that these three measurement systems can be applied to implement a compensation system which comprises one among them, an Elmo controller, and a dSPACE controller, and accomplish static compensation and dynamic compensation in the dual linear-axis stage. The accuracies of the static and dynamic compensation achieve ± 1 μm and ± 2.5 μm, respectively.