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Accurate simulation of photovoltaic characteristics is now a mandatory obligation before validating an experiment; hence, accurate model and parameters of solar cells are indispensable. This paper presents an improved explicit double-diode model based on the Lambert W function (EDDM-LW), and then compares the fitness and parameter extraction performance. By defining two new parameters (κ and τ) to separate the exponential function in double-diode model (DDM) and using the Lambert W function, the explicit expression for I-V characteristics is proposed. In contrast to exiting works, the new parameters can readily be computed by the electrical characteristics of the standard test condition without an implicit characteristic. To verify the accuracy of the proposed model, the fitness difference is first investigated with a solar cell and three different types of solar modules. The results indicate that under the same parameter values, EDDM-LW achieves the lowest root mean square error value and exhibits better fitness in representing the I-V characteristics. In addition, the optimal parameters are extracted by an improved teaching-learning-based optimization algorithm. The experimental results show that the optimal parameter values extracted from EDDM-LW are more accurate than those extracted from DDM. Based on these observations, EDDM-LW can be deemed a useful and practical model for the simulation, evaluation, and optimization of the photovoltaic system.

A green and highly stereoselective method for the synthesis of cis or trans-1,3-disubstituted-tetrahydro-β-carbolines has been developed using water as the solvent. A mixture of cis and trans-1,3-disubstituted-tetrahydro-β-carboline hydrochlorides can be converted to a single cis or trans isomer via a crystallization-induced asymmetric transformation process. It is possible to get both isomers using this method by incorporating different additives in water. This method has advantages such as environmental friendliness, high stereoselectivity, suitability for industrialization, and non-toxicity.

Solar cell model is used in various studies of photovoltaic system. Different methods have been developed to determine model parameters. In this paper, an optimization technique based on cat swarm optimization (CSO) algorithm is proposed to estimate the unknown parameters of single and double diode models. To investigate the effectiveness of proposed approach, comparative studies with other techniques are presented. The evaluation for the quality of identified parameters is also given. Results demonstrate the high performance of developed approach, high accuracy of estimated parameters, and calculated I–V curve is in good agreement with experimental I–V data. In addition, the sensitivity of performance to control parameter of CSO is also investigated. Results show the proposed CSO algorithm can be an effective tool to solve the optimization problem of parameter identification of solar cell models.

A high precision time delay calibration system based on optical fiber switches and fiber coils network for the satellite range measurement system is proposed in this paper. To reach the high time delay precision, the Phase Stabilized Optical Fiber (PSOF), is proposed to use as time delay component instead of the Single Mode Fiber (SMF) to minimize the temperature dependence of transmission delay time. In order to verify the time delay precision, a low coherence interferometry which contains a Michelson interferometer and a Mach-Zehnder interferometer is used to measure the thermal coefficient of delay of the PSOF compared with the SMF from −20 to 60℃. The result showed that by using the PSOF, the temperature error can be decreased by 4.15 times compared with using the standard SMF in the fiber based range measurement system.

Based on the matrix method and clearance vector model, a simple, accurate, efficient and general mechanical reliability analysis method is presented to analyze the reliability of a complex linkage mechanism with structural errors and clearances. The output error variances of the latch needle mechanism in double-needle warp knitting machine are obtained based on this matrix method and verified by Monte-Carlo method. Then, an optimization design method for the latch needle mechanism is presented with the use of genetic algorithm, considering the motion requirement and output errors. The optimized latch needle mechanism can meet the double-dwell motion requirement, and has higher displacement accuracy and reliability under the same structural errors and clearance conditions. This method has practical engineering value in solving the contradiction between high precision loop-forming motion and multi-link accumulative errors, reducing cost, and providing a reference for the optimization design for loop forming mechanism in a warp knitting machine.

We report the first study of using optical coherence tomography (OCT) to inspect the winding quality of fiber optical gyro coils. We use a swept-source OCT system to scan a quadrupole-wind fiber coil for obtaining its two-dimensional and three-dimensional (3D) tomographic images. The defects beneath the surface of the fiber coil, which otherwise are invisible by video inspection, can be clearly identified with such tomographic images. The winding quality of each layer can also be independently visualized with the reconstructed 3D images from different angles or in different sections. We believe that the proposed method will be useful to ensuring the quality production of each and every fiber gyro coil.

We present methods and processes of using a ghost-peak-free distributed polarization crosstalk analyzer (DPXA) to accurately obtain all polarization related parameters of polarization-maintaining (PM) fibers. We show that by first inducing a series equidistant periodic polarization crosstalk peaks along a PM fiber and then measuring the positions and the widths of these peaks using the analyzer, all birefringence related parameters of the PM fiber, including group birefringence, group birefringence variation along the fiber, group birefringence dispersion, and group birefringence temperature coefficient , can be accurately obtained. We further show that the DPXA has the ability to identify and eliminate polarization crosstalk contributions of connectors or splices in the measurement system and therefore can be used to obtain high accuracy measurement of the polarization extinction ratio (PER) of PM fibers. Finally, we propose a set of parameters based on the distributed polarization analysis to quantitatively evaluate the quality of PM fibers. We believe that the methods and processes described in this paper can be widely applied in the industry for the complete characterization of PM optical fibers.

In this paper, an improved model of photovoltaic cell is proposed. By using Lambert W function, the improved model of solar cell is deduced. Meanwhile, the current-voltage and power-voltage curves of photovoltaic cell are calculated and simulated in Matlab/Simulink environment. Compared to the popular model and experimental data, the proposed method shows excellent agreement between the current-voltage points. It is found that the proposed modeling method has less error at the maximum power point state.

A new method is proposed to describe the characteristics of solar cell and module in this article. By using the exact explicit analytical solutions, the current–voltage and power–voltage curves of the corresponding modules are calculated and simulated. In order to extract the parameters of the solar cells, an optimized technique is presented by using Lambert W function and polynomial curve fitting. The accuracy of the model is compared with previous methods in other work. Results have the good agreement between the fitted current–voltage curves and the experimental data. Moreover, error and statistical analyses are carried out to illustrate the accuracy of the estimated parameters and procedure suitability.

We present a novel method to significantly extend the measurement range of an optical frequency domain reflectometry (OFDR) beyond the laser coherence length for both discrete reflection (such as Fresnel reflection) and Rayleigh backscattering measurements. A key to the method is to increase the laser frequency tuning speed while measuring the phase noise of the reflected optical signal that carries the location and reflectivity information. Using this technique in a conventional OFDR with a noise floor of -120ndB and a dynamic range of 53 dB, we achieved a measurable distance of 170 km for Fresnel reflection and 120 km for Rayleigh backscattering using a laser with a coherence length of only 13.6 km.

This paper first presents a 3D analytical model for analyzing the radial air-gap magnetic field between the inner and outer magnetic rotors of the permanent magnet couplings by using the Amperian current model. Based on the air-gap field analysis, the eddy current loss in the isolation cover is predicted according to the Maxwell’s equations. A 3D finite element analysis model is constructed to analyze the magnetic field spatial distributions and vector eddy currents, and then the simulation results obtained are analyzed and compared with the analytical method. Finally, the current losses of two types of practical magnet couplings are measured in the experiment to compare with the theoretical results. It is concluded that the 3D analytical method of eddy current loss in the magnet coupling is viable and could be used for the eddy current loss prediction of magnet couplings.

For a determination of the system’s efficiency and decrease the cost, a low cost system for measuring solar irradiance is designed. By analyzing the influence of solar irradiance and temperature to solar cell, we have found that in case of different temperatures the variation of short-circuit current (Isc) in function of solar irradiation incident (E) is always linear. Then the read-out circuitry is designed to measure and convert the signal which is detected by the photoelectric cell and thermocouples. At last, the software is developed to compensate the temperature and make sure the device work normally. The results of detecting the system show that it’s effective and reliable.

We introduce a parameter called pointing error thermal sensitivity (PETS) for quantitatively determining the quality of a quadrupolar (QAD) fiber coil under radial temperature variations. We show both analytically and experimentally that the pointing error of a fiber gyro incorporating the fiber coil is linearly proportional to the final radial thermal gradient on the coil, with PETS as the proportional constant. We further show that PETS is linearly proportional to another parameter called effective asymmetric length of the coil. By thermally inducing different radial thermal gradients on the fiber coil and measuring the corresponding pointing errors in a gyroscopic measurement setup, we can confidently determine the PETS of the fiber coil and its associated effective asymmetric length caused by imperfections in coil winding. Consequently, we are able to precisely trim the coil to achieve best thermal performance.

We present a method to accurately measure the group birefringence variation with temperature in high-birefringence polarization-maintaining (PM) fibers using a distributed polarization analyzer. By analyzing polarization cross-talk peaks purposely induced at both ends of a PM fiber, the temperature coefficient of group birefringence can be accurately obtained. We confirm the theoretical prediction that the group birefringence of PANDA and TIGER PM fibers decrease linearly with temperature from -40 °C to 80 °C, and find that the temperature coefficients are -5.93 × 10(-7) °C(-1) and -5.29 × 10(-7) °C(-1) for two types of PANDA fibers, and -5.36 × 10(-7) °C(-1) for a TIGER fiber.

This paper proposed the development jacquard control system for carpet tufting machine with step motors driven scroll pattern attachment. The hardware structure of jacquard control system was designed base on CAN Bus. The upper computer controls the step motors and get feedback through CAN communication. By analyze the tufting process data flow, design the function modules and work flowchart, focus on the key module discuss the detail principle, and developed the control system with Borland C++. The control system analyze the design pattern, generate the control information and download it through CAN bus to lower computer, and start the speed synchronous between step motor and spindle to ensure the yarn feeding length in each stitch tufting, and get desired pile height loop piles. The system was test in real production and got the effect as expect.

This paper presents a new method to measure the characteristic parameter of the laser holographic anti-counterfeiting label, with less dependency on the stability of source light. The He-Ne laser, having 5% relative instability, was used as the light source. Based on the nature that one beam of light can be divided into two beams at a fixed ratio, the source light was divided into the reflex and the transmission at the fixed ratio by a piece of glass. As the label was scanned automatically, the intensities of the reflex and the diffraction were measured online and in real time to get the SNR. The data table for contrast was given, which showed the differences between the real value and the calculated value of the intensity of the transmission as the incident beam. The measurement results of the SNR of 8 different versions of labels were also listed. The experimental data demonstrate that the relative error of the transmission intensity is not more than 0.29%, and that of the SNR is less than 2.0%, which is approximately half the error of the original method.

We present a novel method to achieve a space-resolved long- range vibration detection system based on the correlation analysis of the optical frequency-domain reflectometry (OFDR) signals. By performing two separate measurements of the vibrated and non-vibrated states on a test fiber, the vibration frequency and position of a vibration event can be obtained by analyzing the cross-correlation between beat signals of the vibrated and non-vibrated states in a spatial domain, where the beat signals are generated from interferences between local Rayleigh backscattering signals of the test fiber and local light oscillator. Using the proposed technique, we constructed a standard single-mode fiber based vibration sensor that can have a dynamic range of 12 km and a measurable vibration frequency up to 2 kHz with a spatial resolution of 5 m. Moreover, preliminarily investigation results of two vibration events located at different positions along the test fiber are also reported.

We present a novel method for improving the spatial resolution and amplitude accuracy of distributed polarization cross-talk measurements in a polarization maintaining (PM) fiber against its birefringence dispersion. We show that the broadening of measured polarization cross-talk peaks caused by birefringence dispersion can be restored by simply multiplying the measurement data with a compensation function. The birefringence dispersion variable in the function can be obtained by finding the widths of measured cross-talk envelopes at known distances along the fiber. We demonstrate that this method can effectively improve spatial resolution and amplitude accuracy of the space-resolved polarization cross-talk measurements of long PM fibers.

We propose using non-uniform FFT to minimize the degrading effect of frequency tuning nonlinearity of a tunable laser source (TLS) in an optical frequency-domain reflectometry (OFDR) system. We use an auxiliary interferometer to obtain the required instantaneous optical frequency of the TLS and successfully demonstrate 100 times enhancement in spatial resolution of OFDR with only a 20% increase in computation time. The corresponding measurement reflectivity sensitivity is better than -80 dB, sufficient to detect bending induced index changes in an optical fiber.

We describe a novel method based on optical coherence tomography (OCT) for the accurate measurement of the refractive index of in vitro human teeth. We obtain the refractive indices of enamel, dentin, and cementum to be 1.631+/-0.007, 1.540+/-0.013, and 1.582+/-0.010, respectively. The profile of the refractive index is readily obtained via an OCT B scan across a tooth. This method can be used to study the refractive index changes caused by dental decay and therefore has great potential for the clinical diagnosis of early dental caries.