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The dynamic flexible job-shop problem (DFJSP) is a realistic and challenging problem that many production plants face. As the product line becomes more complex, the machines may suddenly break down or resume service, so we need a dynamic scheduling framework to cope with the changing number of machines over time. This issue has been rarely addressed in the literature. In this paper, we propose an improved learning-to-dispatch (L2D) model to generate a reasonable and good schedule to minimize the makespan. We formulate a DFJSP as a disjunctive graph and use graph neural networks (GINs) to embed the disjunctive graph into states for the agent to learn. The use of GINs enables the model to handle the dynamic number of machines and to effectively generalize to large-scale instances. The learning agent is a multi-layer feedforward network trained with a reinforcement learning algorithm, called proximal policy optimization. We trained the model on small-sized problems and tested it on various-sized problems. The experimental results show that our model outperforms the existing best priority dispatching rule algorithms, such as shortest processing time, most work remaining, flow due date per most work remaining, and most operations remaining. The results verify that the model has a good generalization capability and, thus, demonstrate its effectiveness. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This paper presents a new parallel three-level soft switching pulse-width modulation (PWM) converter. The proposed converter has two circuit cells operated by the interleaved PWM modulation. Thus, the ripple currents at input and output sides are reduced. Each circuit cell has two three-level zero voltage switching circuits sharing the same power switches. Therefore, the current and power rating of the secondary side components are reduced. Current double rectifier topology is selected on the secondary side to decrease output ripple current. The main advantages of the proposed converter are soft switching of power switches, low ripple current on the output side and low-voltage rating of power switches for medium-power applications. Finally, the performance of the proposed converter is verified by experiments with 1 kW prototype circuit. [ABSTRACT FROM PUBLISHER]

Leakage of liquid electrolyte and damage to dye-sensitized solar devices due to ultraviolet irradiation typically result in the poor long-term stability of liquid-electrolyte-based dye-sensitized solar cells (DSSCs). In this study, a simple in situ gelation (ISG) process is developed for the quasi-solid-state electrolyte (QSE) in DSSCs using polyvinyl butyral (PVB), a polymer used worldwide in laminated glass. The diffusion coefficients and ionic conductivities of the QSEs are analyzed, and the optimal ionic conductivity is found to be approximately 2.64 × 10−3 S cm−1, which is approximately six orders of magnitude higher than that of the original PVB thin film. The ISG–QSE devices exhibit a high conversion efficiency of 4.86% at 100 mW cm−2; this is approximately 98% of the efficiency of corresponding liquid electrolyte (LSE) cells. Moreover, the devices can maintain a remarkable 98% of their original efficiency after 2100 working hours owing to the addition of 5% UV absorber to the ISG electrolyte. In addition, the ISG-electrolyte-based DSSCs can drive a 5 × 5 cm2 electrochromic (EC) device, demonstrating the potential for the application of this combination in “smart windows” in the future. [ABSTRACT FROM AUTHOR]

SUMMARY 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 1 kW, are presented to demonstrate the converter performance. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: Biohydrogen is usually produced via dark fermentation, which generates CO2 emissions and produces soluble metabolites (e.g., volatile fatty acids) with high chemical oxygen demand (COD) as the by-products, which require further treatments. In this study, mixotrophic culture of an isolated microalga (Chlorella vulgaris ESP6) was utilized to simultaneously consume CO2 and COD by-products from dark fermentation, converting them to valuable microalgae biomass. Light intensity and food to microorganism (F/M) ratio were adjusted to 150 μmol m−2 s−1 and F/M ratio, 4.5, respectively, to improve the efficiency of assimilating the soluble metabolites. The mixotrophic microalgae culture could reduce the CO2 content of dark fermentation effluent from 34% to 5% with nearly 100% consumption of soluble metabolites (mainly butyrate and acetate) in 9 days. The obtained microalgal biomass was hydrolyzed with 1.5% HCl and subsequently used as the substrate for bioH2 production with Clostridium butyricum CGS5, giving a cumulative H2 production of 1276 ml/L, a H2 production rate of 240 ml/L/h, and a H2 yield of 0.94 mol/mol sugar. [Copyright &y& Elsevier]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract: In this work, Chlorella vulgaris ESP6 was used to assimilate the soluble metabolites in the hydrogen fermentation broth of Clostridium butyricum CGS5 to obtain valuable microalgae biomass. The results show that C. vulgaris ESP6 could grow on the 4-fold diluted dark fermentation broth. Acetate was efficiently utilized during the growth of C. vulgaris ESP6, whereas the microalgae growth was inhibited by lactate, butyrate, and when their concentrations were higher than 0.5, 0.1, and 2.72g/L, respectively. C. vulgaris ESP6 could completely consume butyrate (the most abundant dark fermentation metabolite) when it was grown on Tris–Acetate–Phosphate medium under a food to microorganism (F/M) ratio of 1.11. [Copyright &y& Elsevier]

This paper proposes a zero-voltage switching (ZVS) pulsewidth modulation (PWM) dc/dc converter with current double rectifiers to achieve ZVS for all switches under a wide range of load conditions and input voltages. Two three-level PWM circuits sharing the same power switches are adopted in the proposed converter to reduce the voltage stress of each MOSFET at Vin/2 and achieve load current sharing. Thus, the current stress and power rating at the secondary-side components are reduced. The current double rectifiers are used at the secondary side to partially cancel the output ripple current. Thus, the sizes of the magnetic components and output filter capacitance are reduced. Due to the resonant behavior by the resonant inductance and resonant capacitance at the transition interval, all switches are turned on at ZVS. The experimental results based on a 1-kW prototype are provided to verify the operation principle of the proposed converter. [ABSTRACT FROM PUBLISHER]

Abstract: Biodiesel is a promising substitute for petroleum diesel, and has been commercialized and utilized in many countries. Conventional chemical or physical methods used for biodiesel production face the drawbacks of high energy consumption or intensive use of chemicals. In contrast, using lipase-catalyzed transesterification for biodiesel synthesis is clean, effective, and water tolerance. Therefore, in this work, a self-developed Burkholderia lipase was immobilized onto hydrophobic magnetic particles (HMPs) for biodiesel production. Transesterification with the immobilized lipase could be repeatedly carried out six times without severe activity loss. The optimal conditions for the enzymatic transesterification were identified as: room temperature, 200rpm agitation, 10% water content, and a methanol-to-oil molar ratio of 4:1. Under these conditions, the conversion of oil to fatty acid methyl esters (FAMEs) reached nearly 70% within 12h, giving a biodiesel production rate of 43.5g/L/h. [Copyright &y& Elsevier]

Abstract: In this work, a carbohydrate-rich microalga, Chlorella vulgaris ESP6, was grown photoautotrophically to fix the CO2. The resulting microalgal biomass was hydrolyzed by acid or alkaline/enzymatic treatment and was then used for biohydrogen production with Clostridium butyricum CGS5. The C. vulgaris biomass could be effectively hydrolyzed by acid pretreatment while similar hydrolysis efficiency was achieved by combination of alkaline pretreatment and enzymatic hydrolysis. The biomass of C. vulgaris ESP6 containing a carbohydrate content of 57% (dry weight basis) was efficiently hydrolyzed by acid treatment with 1.5% HCl, giving a reducing sugars (RS) yield of nearly 100%. C. butyricum CGS5 could utilize RS from C. vulgaris ESP6 biomass to produce hydrogen without any additional organic carbon sources. The optimal conditions for hydrogen production were 37 °C and a microalgal hydrolysate loading of 9 g RS/L with pH-controlled at 5.5. Under the optimal conditions, the cumulative H2 production, H2 production rate, and H2 yield were 1476 ml/L, 246 ml/L/h, and 1.15 mol/mol RS, respectively. The results demonstrate that the C. vulgaris biomass has the potential to serve as effective feedstock for dark fermentative H2 production. [Copyright &y& Elsevier]

Abstract: 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 ±0.6μm for straightness, ±0.8 arcsec for angular error, and ±1.2μm for linear displacement. [Copyright &y& Elsevier]

Abstract: Burkholderia sp. C20 strain isolated from food wastes produces a lipase with hydrolytic activities towards olive oil. Fermentation strategies for efficient production of this Burkholderia lipase were developed using a 5-L bench top bioreactor. Critical factors affecting the fermentative lipase production were examined, including pH, aeration rate, agitation rate, and incubation time. Adjusting the aeration rate from 0.5 to 2vvm gave an increase in the overall lipase productivity from 0.057 to 0.076U/(mlh), which was further improved to 0.09U/(mlh) by adjusting the agitation speed to 100rpm. The production of Burkholderia lipase followed mixed growth-associated kinetics with a yield coefficient of 524U/g-dry-cell-weight. The pH optimum for cell growth and lipase production was different at 7.0 and 6.0, respectively. Furthermore, stepwise addition of carbon substrate (i.e., olive oil) enhanced lipase production in both flask and bioreactor experiments. [Copyright &y& Elsevier]

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. [ABSTRACT FROM AUTHOR]

Abstract: A glucose biosensor with superior accuracy and sensitivity was successfully developed based on an interdigital transducer array (IDA) microelectrode. The IDA microelectrode was prepared by a photolithography procedure with sputter coated thin layers of both gold and SiO2, followed by tetrafluoromethane (CF4) plasma treatment. The enzymatic interactions between glucose and the reactants were monitored by cyclic voltammetry method to determine the blood glucose concentration. The surface properties of the developed glucose biosensor were characterized by electron spectroscopy for chemical analysis (ESCA), atomic force microscopy (AFM), and surface wettability. The correlations between the results of surface analyses and the current responses indicated that the CF4 plasma facilitated both the exposure of gold layer underneath the protection layer and the raise of surface hydrophobicity, and therefore the enhancement of the current responses. The developed IDA-microelectrode-based glucose biosensor showed particular precision and excellent reproducibility in measuring glucose concentration under the presence of common interferences and in real human blood measurements. Moreover, the IDA microelectrodes displayed a sensitivity of 0.13μA/(mg/dL) which is much higher than commercially available products. [ABSTRACT FROM AUTHOR]

Abstract: 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. [Copyright &y& Elsevier]

One of the key challenges in the promotion of web-based learning is the development of effective collaborative learning environments. We posit that the structuration process strongly influences the effectiveness of technology used in web-based collaborative learning activities. In this paper, we propose an ant swarm collaborative learning (ASCL) environment based on a swarm intelligence system (SIS) that structures opportunities for effective collaboration and learning in a dynamic way. The results of our experiments indicate that: (1) the self-organizing behavior of SIS is positively associated with system appropriation; (2) the multi-agent-based mechanism of SIS is positively associated with system appropriation; (3) the cohesive capability of SIS is positively associated with system appropriation; and (4) the learner’s tendency toward system appropriation is positively associated with learning effectiveness. Our findings also show that learners in an ASCL environment outperform their counterparts in a general web-based learning (GWL) environment. We conclude that different types of technological support can influence the achievement in a web-based learning environment. [Copyright &y& Elsevier]

Abstract: An indigenous Cellulosimicrobium cellulans GS6 isolate able to solubilize insoluble phosphate complexes in soil is a potential bacterial fertilizer. Enclosure of the phosphate-solubilizing bacterium (PSB) in biodegradable capsules may protect the PSB cells inoculated into soil and, in the meantime, enable the control of cell release that confers long-term fertilizing effects. In this study, calcium alginate (CA) was used as the core matrix to encapsulate cells of C. cellulans GS6. The cell-liberating properties of the CA-based capsules were modified by blending with a variety of supplemental materials (SM), including chitin, cellulose, olive oil, and gelatin. The experimental results showed that the maximum cell-release percentage (MCR%) of the capsules decreased in the order of CA-cellulose>CA-olive oil>CA-chitin>CA-gelatin>CA. Furthermore, a mass transport model was developed to accurately describe the kinetics of cell release results for each capsule. The diffusion coefficient (D e) of each capsule was also determined from the model simulation. We found that the estimated D e values are positively correlated to the release rate with rare exceptions. Lastly, as our results underscored the crucial roles that the type of capsules plays in the rate and amount of cell release, controlled release of the bacterial fertilizer (C. cellulans GS6 cells) may be achieved via the design of capsule materials. [Copyright &y& Elsevier]

Abstract: In this work, a simple, inexpensive, and efficient method of preparing immobilized lipase is presented. The lipase originating from a newly isolated indigenous strain Burkholderia sp. C20 was immobilized onto cellulose nitrate (CN) membrane via filtration. The CN–immobilized lipase was able to retain 60% of its original activity after repeated uses for nine times. The thermal stability of the lipase was also slightly improved after immobilization. The optimal reaction conditions of CN–lipase were pH 9.0 and 55°C, which are similar to those for the suspended lipase. Both suspended and immobilized lipase could hydrolyze the six oil substrates examined, while immobilized lipase displayed less specificity over the oil substrates. Kinetic analysis shows that the dependence of lipolytic activity of both suspended and immobilized lipase on oil substrate concentration can be described by Michaelis–Menten model with good agreement. The estimated kinetic constants for suspended lipase (v max =243.9U/mg, K m =0.024mM) and immobilized lipase (v max =32.8U/mg, K m =5.61mM) were quite different. Employment of immobilization seemed to result in a decrease in v max and an increase in K m, most likely due to the mass transfer resistance arising from formation of micelles during the lipase immobilization process. [Copyright &y& Elsevier]

e-Learning is bringing training to the attention of upper management in a way that other learning technologies have never done. Web-based training will remain predominant to the design and delivery of workplace learning in the 21st century because of its advantages over traditional classroom-based training. A comprehensive framework that delineates the relationship between learner control and learning effectiveness in educational training is absent. This study therefore aims to fill this void. Unlike previous relevant research, this study compares learning effectiveness between two educational training delivery methodologies: traditional classroom-based training (TCT) and web-based training (WBT). Our framework focuses on learning effectiveness of web training in the context of the educational training programmes of two colleges' administration application systems. Based on the WBT literature, this study uses a model that investigates the relationship between learner control and learning effectiveness under five dimensions: learning performance, learner satisfaction, accumulation of learning experience, document navigation, and problem solving. To compare learning effectiveness between TCT and WBT we conducted a field experiment. Data were collected from two colleges that received training on their administration application systems. A total of 288 usable responses were analysed. The results allow five conclusions to be drawn: (1) learners receiving WBT achieved better learning performance than their counterparts receiving TCT; (2) learners receiving WBT reported higher levels of satisfaction than their counterparts with the traditional approach; (3) learners receiving WBT accumulated more learning experience than their counterparts with TCT; (4) WBT provided more integrated document navigation than the traditional format; (5) WBT offered faster problem solving mechanisms than TCT. The implications of this study are discussed and further research directions are proposed. [ABSTRACT FROM AUTHOR]

Abstract: Multicast routing is an effective way to communicate among multiple hosts in a network. It outperforms the basic broadcast strategy by sharing resources along general links, while sending information to a set of predefined multiple destinations concurrently. However, it is vulnerable to component failure in ad hoc network due to the lack of redundancy, multiple paths and multicast tree structure. Tree graph optimization problems (GOP) are usually difficult and time consuming NP-hard or NP-complete problems. Genetic algorithms (GA) have been proven to be an efficient technique for solving the GOP, in which well-designed chromosomes and appropriate operators are key factors that determine the performance of the GAs. Limited link, path constraints, and mobility of network hosts make the multicast routing protocol design particularly challenging in wireless ad hoc networks. Encoding trees is a critical scheme in GAs for solving these problems because each code should represent a tree. Prüfer number is the most representative method of vertex encoding, which is a string of n −2 integers and can be transformed to an n-node tree. However, genetic algorithm based on Prüfer encoding (GAP) does not preserve locality, while changing one element of its vector causes dramatically change in its corresponding tree topology. In this paper, we propose a novel GA based on sequence and topology encoding (GAST) for multicast protocol is introduced for multicast routing in wireless ad hoc networks and generalizes the GOP of tree-based multicast protocol as well as three associated operators. It has revealed an efficient method of the reconstruction of multicast tree topology and the experimental results demonstrated the effectiveness of GAST compare to GAP technique. [Copyright &y& Elsevier]

Abstract: This work utilized experimental design methodology to improve lipase production from an indigenous bacterial isolate identified as Burkholderia sp. C20. The factors affecting the lipase production of Burkholderia sp. C20 were screened by two-level factorial design and the optimal conditions for lipase production were determined by response surface methodology (RSM). Preliminary batch tests were employed to obtain the favorable conditions for lipase activity analysis and found that the optimal temperature and pH for lipase activity assay was 55°C and 9.0, respectively. Comparison of cell growth and lipase activity profiles shows that the fermentation time of 67h was suitable for harvesting lipase products in the batch culture of Burkholderia sp. C20. A two-level design of 25−1 experiments was applied to identify the most significant influential factors out of five factors; namely, temperature, pH, and concentrations of olive oil, CASO and NaCl. After analysis with two-level design, concentrations of CASO and NaCl were selected for RSM analysis, predicting an optimal composition of 0.12% and 0.16% for CASO and NaCl, respectively. Using the optimal conditions, lipase production by Burkholderia sp. C20 was enhanced nearly 5 fold (from 0.8 to 3.9U/ml). [Copyright &y& Elsevier]

Abstract: The Soj and Spo0J proteins, together with one or more parS sequences, are crucial to chromosome segregation and the progression of cell cycle in many bacteria. In Helicobacter pylori, genes coding for Soj and a plasmid replication–partition-related protein containing a Spo0J or ParB conserved domain, together with two putative parS sites identified in this study, were found to be located within the origin-proximal 20–30% of the circular chromosome. Recombinant H. pylori Spo0J bound specifically to the two putative parS sequences and that of Bacillus subtilis. In addition, hydrolysis of ATP by H. pylori Soj was accelerated in the presence of parS and/or Spo0J. Protein–protein interactions, intracellular levels, and subcellular localization of Soj and Spo0J were analyzed through polyclonal antibodies directed against recombinant Soj and Spo0J. This study was the first implication of the existence of a functional parABS system in H. pylori. [Copyright &y& Elsevier]

Abstract: In this paper, two systems for the measurement of the error motion and angular indexing of a rotary indexing table have been developed. A laser diode, a laser holder and a position sensitive detector (PSD) are integrated as a simple measuring device for the measurement of the rotary error without using a precision reference artifact (a cylinder or a sphere), multiple probes or error separation methods. The laser diode is assembled in the laser holder and fixed on the rotary table. The PSD is set up above the laser holder to detect the position of an incident laser beam from the laser diode. When the rotary table rotates, the rotary error changes the direction of the incident beam and also the position of the spot on the PSD. For the measurement of the angular indexing, a reflective diffraction grating and two PSDs are integrated as a high-resolution angle measuring device without using an autocollimator or a laser interferometer system. The diffraction grating is set at the center of the rotary table and reflects an incident laser beam into several diffractive rays. Two PSDs were set up for detecting the positions of ±1st-order diffraction rays. A simple algebraic method is used to solve the angular indexing through an optical analysis. The experimental results showed the feasibility of the proposed test devices. [Copyright &y& Elsevier]

This paper contains a description of four-degrees-of-freedom microstage, designed to replace manual adjustment mechanism in a roundness measurement machine for the compensation of eccentricity. Four-degrees-of-freedom motion (two-translational and two-rotational motion) was obtained by four piezoelectric actuators that were set up on the same plane to minimize the effect of the abbe’s offset. The microstage was fixed on a rotary table to compensate not only for the x- and y-position errors, but also for the angle errors about the x- and y-axis. Repeatability, calibration and experimental tests were carried out and the results showed the proposed design was easy to assemble for most types of roundness test machines and had sufficient capability to compensate for the eccentricity. [Copyright &y& Elsevier]

Traditionally, the least-squares method is applied on modern measurement systems for quality assurance. The least-squares method can only provide an approximate solution to the real values of conical parts. It may also result in a possible overestimation of tolerance errors on various engineering surfaces. Thus, a heuristic approach is presented in this paper to efficiently evaluate the cone type error based on the minimum zone definition using genetic algorithms (GAs). GAs show more flexibility in evaluating the engineering surfaces via adjusting the genetic parameters. Two fitness functions were also developed for improving the speed of convergence of GAs. Numerical results indicate that the genetic algorithm provides better accuracy and efficiency and can thus be used to solve difficult product attitude evaluation problems in engineering metrology. [Copyright &y& Elsevier]

In this study, a laser linear encoder with three degrees of freedom (3-DOFs) based on diffraction and interference was developed to measure the linear displacement and two angular errors of a linear moving stage. Parts of the linear motion errors induced from the two angular errors can be calculated by this prototype 3-DOF laser encoder. It was an effective method for online error calculation and compensation to improve precision stage performance. This new function was superior to other laser encoders. The verification results showed that the resolution is 20 nm. It detected displacements relative to an external grating scale with accuracy of about ±150 nm for a measuring range of ±1 mm, and detected the angular errors with related accuracy of about ±1 arc sec for a measuring range of ±100 arc sec. [ABSTRACT FROM AUTHOR]

Parkinson's disease (PD) is an irreversible neurodegenerative disease that has serious impacts on patients' lives. To provide timely accurate treatment and delay the deterioration of the disease, the accurate early diagnosis and clinical score prediction of PD are extremely important. Differing from previous studies on PD, we propose a network combining feature selection method with feature learning to obtain the most discriminative feature representation for longitudinal early diagnosis and clinical score prediction. Specifically, we first preprocess the multi-modal neuroimaging data at multiple time points to extract original longitudinal multi-modal features. Then, the feature selection method is performed to preliminary reduce the feature dimensions. Finally, the stacked sparse nonnegative autoencoder (SSNAE) is employed to obtain more discriminative longitudinal multi-modal features to improve the accuracy of early diagnosis and clinical score prediction at multiple time points. To verify our proposed network, diverse and extensive experiments are performed on the Parkinson's Progression Markers Initiative dataset, which aims to identify biological markers of PD risk, onset and progression. The results demonstrate that our proposed method is more efficient and achieves promising performance on both longitudinal early diagnosis and clinical scores prediction compared to state-of-the-art methods. [ABSTRACT FROM AUTHOR]

The advent of intelligent technology has spurred most large companies to introduce business intelligence systems (BIS), but those with low information maturity still have a wait-and-see attitude towards BIS. In order to accelerate the introduction of BIS, this study found and analyzed the critical factors (CFs) considered by companies when introducing BIS. First, the literature on factors considered by companies to introduce BIS was reviewed. The three stages before, during, and after introduction in marketing that organizations undergo during the procurement process were developed into a three-layer hierarchy factor table. An expert questionnaire with pairwise factors was then designed and sent to senior executives in companies that had introduced BIS, and the weights of all factors were calculated by the fuzzy analytic hierarchy process (FAHP) based on the collected questionnaire data. After this, four critical factors—system function integrity, approaching corporate strategy, licensing fee, and information technology maturity—were determined objectively by using the conditions for the acceptable advantage of Vlse Kriterijumska Optimizacija Kompromisno Resenje (VIKOR) and further explored in order to help companies input fewer resources, introduce BIS efficiently, and thus increase their decision-making power. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Web-based self-learning (WBSL) has received a lot of attention in recent years due to the vast amount of varied materials available in the Web 2.0 environment. However, this large amount of material also has resulted in a serious problem of cognitive overload that degrades the efficacy of learning. In this study, an information graphics method is proposed to resolve this problem. This method is based on social tagging, which is used to visualize the relationships among materials and can thus assist learners in facilitating learning. To examine the feasibility of the proposed method for managing cognitive load, an experimental model was designed in which cognitive load theory was adopted as the theoretical framework. A total of 60 university students participated in the experiment, and the partial least squares method was used to verify the experimental model. The results show that the information graphics method has a positive impact on three types of cognitive load, namely intrinsic, extraneous, and germane. Furthermore, intrinsic and germane cognitive load have a positive influence on perceived learning effectiveness, while extraneous cognitive load does not have a significant influence. One possible reason for this outcome is that the problem of visual load was not considered in the design of this study. The overall summary of the findings is that the use of social tagging can effectively manage cognitive load and positively links to perceived learning effectiveness. [ABSTRACT FROM AUTHOR]

Abstract: 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 μm measurement range is ± 1 μm, and the accuracy in measuring the angular errors of pitch and yaw within a ±50 arc sec measurement range is ±1 arc sec. [Copyright &y& Elsevier]

Abstract: Text retrieval has received a lot of attention in computer science. In the text retrieval field, the most widely-adopted similarity technique is using vector space models (VSM) to evaluate the weight of terms and using Cosine, Jaccard or Dice to measure the similarity between the query and the texts. However, these similarity techniques do not consider the effect of the sequence of the information. In this paper, we propose an integrated text retrieval (ITR) mechanism that takes the advantage of both VSM and longest common subsequence (LCS) algorithm. The key idea of the ITR mechanism is to use LCS to re-evaluate the weight of terms, so that the sequence and weight relationships between the query and the texts can be considered simultaneously. The results of mathematical analysis show that the ITR mechanism can increase the similarity on Jaccard and Dice similarity measurements when a sequential relationship exists between the query and the texts. [Copyright &y& Elsevier]

Laser trackers are widely used in industry for tasks such as the assembly of airplanes and automobiles, contour measurement, and robot calibration. However, laser trackers are expensive, and the corresponding solution procedure is very complex. The influence of measurement uncertainties is also significant. This study proposes a three-dimensional space position measurement system which consists of two tracking modules, a zero tracking angle return subsystem, and a target quadrant photodiode (QPD). The target QPD is placed on the object being tracked. The origin locking method is used to keep the rays on the origin of the target QPD. The position of the target QPD is determined using triangulation since the two laser rays are projected onto one QPD. Modulation and demodulation are utilized to separate the coupled positional values. The experiment results show that measurement errors in the X, Y, and Z directions are less than ±0.05% when the measured object was moved by 300, 300, and 200 mm in the X, Y, and Z axes, respectively. The theoretical measurement error estimated from the measurement model is between ±0.02% and ±0.07% within the defined measurable range. The proposed system can be applied to the measurements of machine tools and robot arms. [ABSTRACT FROM AUTHOR]

Abstract: 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 4.5μm, respectively. [Copyright &y& Elsevier]

Abstract: To minimize the size of a stage with more DOF motion, this paper concentrates on the design, manufacturing process and control of a 5DOF thin coplanar nanometer-scale stage with high accuracy and multiple DOF motion. This paper uses the features of a flexible structure to develop a 200mm×200mm×35mm thin coplanar nanometer-scale stage with 5DOF that allows the increase or decrease of axis action in accordance with various needs. The flexible structure of the thin coplanar nanometer-scale stage includes a cylindrical flexible body and an arc flexible body. The thin coplanar nanometer-scale stage allows for three-translational and two-rotational motions and is provided with eight piezoelectric actuators—one on the X-axis, another on the Y-axis, and the others on the Z-axis. The displacement characteristics of the output member of the stage were measured with the built-in capacitive sensors. It also used an analysis and identification controller design method for piezoelectric actuated systems. From the results, it can be seen that the performance of this controller is good and 10nm controlling error of the step input can be obtained. The controlling error of the rotational angle is about 0.004arcsec. [Copyright &y& Elsevier]

Abstract: An indigenous purple nonsulfur bacterium Rhodopseudomonas palustris WP3-5 was used to produce hydrogen phototrophically from acetate (HAc) and butyrate (HBu), which are the major soluble products from acidogenic dark fermentation. Statistical experimental design methodology was applied to identify optimal composition of the two carbon substrates in the medium, leading to better H2 production performance of R. palustris WP3-5. Three performance indexes were used to assess the effectiveness of the phototrophic H2 production; they were H2 yield (), maximum H2 production rate (R max) and maximum cumulative H2 evolution (H max). An overlay contour plot was used to determine the optimal concentration range of HAc and HBu, taking into account all three performance indexes (i.e., R max, H max, and ) simultaneously. With the response surface analysis, R. palustris WP3-5 could produce H2 efficiently with the best R max, H max, and of 39.5ml/h, 2738ml, and 51.6%, respectively. This performance is superior to most reported values in the literature, indicating that the statistical experimental design is an effective tool to improve phototrophic H2 production with R. palustris WP3-5. [Copyright &y& Elsevier]

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. [ABSTRACT FROM AUTHOR]

Abstract: A two-stage process combining dark/photo fermentation was used to increase the overall hydrogen yield from sucrose and also to reduce the chemical oxygen demand (COD) in the effluent. Dark-H2 fermentation was conducted using Clostridium pasteurianum CH4, giving a maximum H2 production yield of 3.80mol H2/mol sucrose. The soluble metabolites resulting from dark fermentation, consisting of butyric and acetic acid, were further used for H2 production in the subsequent photo fermentation. Using soluble products from dark fermentation as substrate, Rhodopseudomonas palustris WP3-5 could produce H2 phototrophically, elevating the total hydrogen yield from 3.80 (dark fermentation) to 10.02mol H2/mol sucrose (dark/photo fermentation). Meanwhile, a 72.0% COD removal was also achieved. When the photobioreactor was illuminated with side-light optical fibers and was supplemented with 2.0% (w/v) of clay carriers, the overall H2 yield of the two-stage process was further enhanced to 14.2mol H2/mol sucrose with a nearly 90% COD removal. Continuous photo fermentation was also carried out at 96h HRT using effluent from dark fermentation as the feed. The continuous culture maintained stable for nearly 10 days with an average H2 yield of 10.21mol H2/mol sucrose. This demonstrates the feasibility of using the two-stage process combining dark and photo fermentation for simultaneous hydrogen production and COD removal. [Copyright &y& Elsevier]

A high resolution six degrees of freedom (6-DOF) optical vibrometer is proposed. 6-DOF vibrations can be simultaneously measured using the proposed optical vibrometer, which reduces measurement time and number. The performance of the proposed vibrometer is verified by experiments. The results show that the accuracy of the proposed optical vibrometer is ±30 nm/200 nm and ±0.04 arcsec/0.1 arcsec at 1000 Hz. [ABSTRACT FROM AUTHOR]