Controllable high repetition rate gain-switched Nd：YVO4 microchip laser

We demonstrated a monolithic, compact, diode-pumped gain-switched Nd:YVO4 laser at 1.064 μ m wavelength withcontrollable repetition rate of I Hz to 25 kHz. Stable gain-switched pulse train with maximum repetition rate of 25 kHz and pulse width of 16 ns was obtained.     

Raman crystal lasers in the visible and near-infrared

Raman lasers based on potassium gadolinium tungstate and lead tungstate crystals pumped bya≈120 ps Nd: YAG laser at 1.064 μm were developed. High reflection mirrors for the Stokes wavelength have been used to generate near-infrared and eye safe spectral region of 1.15–1.32 μm. Second harmonic generation of the generated Raman lasers was observed. Eifficient multiple Stokes and anti-Stokes picosecond generation in 64 crystals have been shown to exhibit stimulated Raman scattering on about 700 lines covering the whole visible and near-infrared spectrum. All stimulated Raman scattering (SRS) wavelengths in the visible and near-infrared spectrum are identified and attributed to the SRS-active vibration modes of these crystals.     

An Investigation of the Alignment Method With Polytomous Indicators Under Conditions of Partial Measurement Invariance

The alignment method (Asparouhov & Muthén, 2014) is an alternative to multiple-group factor analysis for estimating measurement models and testing for measurement invariance across groups. Simulation studies evaluating the performance of the alignment for estimating measurement models across groups show promising results for continuous indicators. This simulation study builds on previous research by investigating the performance of the alignment method’s measurement models estimates with polytomous indicators under conditions of systematically increasing, partial measurement invariance. We also present an evaluation of the testing procedure, which has not been the focus of previous simulation studies. Results indicate that the alignment adequately recovers parameter estimates under small and moderate amounts of noninvariance, with issues only arising in extreme conditions. In addition, the statistical tests of invariance were fairly conservative, and had less power for items with more extreme skew. We include recommendations for using the alignment method based on these results.     

Comparison of high order aberration after conventional and customized ablation in myopic LASIK in different eyes of the same patient

Purpose: To verify whether there exists any difference in higher order aberrations after undergoing myopic LASIK (laser in situ keratomileusis) with conventional ablation and customized ablation in different eyes of the same patient. Methods: This was a prospective randomized study of 54 myopic eyes (27 patients) that underwent LASIK using the Nidek EC-5000 ex-cimer laser system (Nidek, Gamagori, Japan). Topography-guided customized aspheric treatment zone (CATz) was used in the first eye of the patient (study group) and the other eye of the same patient was operated on with conventional ablation (control group). Higher order aberrations [root-mean-square (RMS) in the 5-mm zone] of both groups were observed with the Nidek OPD-Scan aberrometer before and 3 months after LASIK. Preoperative mean refractive error was similar between two eyes of the same patient (t=?0.577, P>0.05). Results: Preoperatively, higher order aberrations (RMS in the 5-mm zone) in the CATz ablation and conventional groups were (0.3600±0.0341) μm and (0.2680±0.1421) μm, respectively. This difference was not statistically significant (t=1.292, P>0.05). Three months after LASIK, higher order aberrations (RMS in 5-mm zone) in the CATz ablation and conventional groups were (0.3627±0.1510) μm and (0.3991±0.1582) μm, respectively. No statistically significant difference was noted between pre- and postoperative higher order aberrations in the CATz group (t=?0.047, P>0.05). However, a statistically significant increase in higher order aberrations was observed after conventional ablation (t=?5.261, P<0.05). A statistically sig-nificant difference was noted in the increase of higher order aberrations after LASIK between groups (t=?2.050, P=0.045). Con-clusion: LASIK with conventional ablation and topography-guided CATz ablation resulted in the same BSCVA (best specta-cle-corrected visual acuity) 3 month after LASIK. Higher order aberrations were increased, but the increase of higher order ab-errations after customized ablation treatment was less than that after conventional ablation.     

A 155 Mbps laser diode driver with automatic power and extinction ratio control

An integrated laser diode driver(LDD) driving an edge-emitting laser diode was designed and fabricated by 0.35 μm BiCMOS technology. This paper proposes a scheme which combines the automatic power control loop and temperature com-pensation for modulation current in order to maintain constant extinction ratio and average optical power. To implement tem-perature compensation for modulation current,a novel circuit which generates a PTAT current by using the injecting base current of a bipolar transistor in saturation region,and alternates the amplifier feedback loop(closed or not) to control the state of the current path is presented. Simulation results showed that programmed by choice of external resistors,the IC can provide modu-lation current from 5 mA to 85 mA with temperature compensation adjustments and independent bias current from 4 mA to 100 mA. Optical test results showed that clear eye-diagrams can be obtained at 155 Mbps,with the output optical power being nearly constant,and the variation of extinction ratio being lower than 0.7 dB.     

Control of pinhole defects formation in semi-flexible coaxial cable by vertical tin-plating process

Holistic tin-plating on the outer conductor is one of the key processes in the manufacture of semi-flexible coaxial cable, which is widely applied to the third generation (3G) mobile communication system. However, in the traditional horizontal tin-plating process, disadvantages such as the pinhole defects and low productivity effect cannot be avoided. In this paper, a vertical tin-plating process was proposed to reduce the pinhole defects and improve the tincoating quality. Compared with the traditional horizontal tin-plating process, the immersion length was reduced from 300-400 mm to 10-100 mm and the tin-plating time was reduced from 7 s to 3 s in the proposed method. The experimental results indicate that immersion length and time are key parameters for the tin-plating quality. With this new tin-plating process, the experimental results show that the pinhole defects can be eliminated effectively by controlling the immersion depth below 100 mm and tin-plating time at 3 s. The thickness of tin-coating increased from not more than 5 μm to 12.3 μm with the proposed vertical tin-plating process. Meanwhile, the thickness of the intermetallic compounds (IMCs) layer between the tin-coating and copper wires was reduced from 3.26 μm to 0.62 μm if the immersion time decreased from 30 s to 1 s. Besides, a self-developed flux, which possesses a boiling point or decomposed temperature of active components over 300℃, exhibits a better efficiency in reducing the pinhole formation.     

Clock generator and OOK modulator for RFID application

The clock generator and OOK modulator for RFID (Radio Frequency Identification) presented in this paper consist of a current source and delay elements. The simple constant-gm structure is adopted in the current source design and the current consumption of the current source is only about 2 μA. The delay elements, the clock generator and OOK modulator are introduced in detail in the paper. The designed circuits are fabricated by 0.6 μm CMOS process. The area of the core circuit is only about 400 μmμ0 μm. The delay time of all three samples is in the range of 9 μs to 21 μs when the supply voltage varies from 2 V to 4 V. As the measured results satisfy the system requirements, these circuit structures are suitable for RFID application.     

激光准直测量系统的运用和常见故障处理

基准线法是观测直线型建筑物水平位移的重要方法,文章介绍了捣固车激光准直测量系统的组成、工作原理和作用,重点介绍了激光准直测量系统的操作方法,总结激光准直测量系统常见故障的产生原因、处理方法以及激光准直测量系统的维护保养。     

Numerical investigation of confined swirling gas-solid two phase jet

This paper presents ak-ε-k _p multi-fluid model for simulating confined swirling gas-solid two phase jet comprised of particle-laden flow from a center tube and a swirling air stream entering the test section from the coaxial annular. A series of numerical simulations of the two-phase flow of 30 μm, 45 μm, 60 μm diameter particles respectively yielded results fitting well with published experimental data. Project is supported by Zheijiana Provincial Natural Science Foundation (No. 598017)     

A study of the relationship between expression level of TRF1 protein and telomerase activity in human acute leukemia

INTRODUCTION Telomeres are distinctive DNA-protein struc-tures that cap the ends of linear chromosomes.It is very important to keep the chromosomes stabilization.Telomerase activity is closely linked to attainment of cellular immortality,a step in carcinogenesis,while lack of such activity contributes to cellular senes-cence.Telomerase is activated in more than85%ofmalignant tumors(Hiayma et al.,1997).Human te-lomeric repeat binding factor1(TRF1)is a telomere associated with proteins a…     

Large eddy simulation of a particle-laden turbulent plane jet

Gas-solid two-phase turbulent plane jet is applied to many natural situations and in engineering systems. To predict the particle dispersion in the gas jet is of great importance in industrial applications and in the designing of engineering systems. A large eddy simulation of the two-phase plane jet was conducted to investigate the particle dispersion patterns. The particles with Stokes numbers equal to 0.0028, 0.3, 2.5, 28 (corresponding to particle diameter 1 μm, 10μm, 30μm, 100μm, respectively) inRe=11 300 gas flow were studied. The simulation results of gas phase motion agreed well with previous experimental results. And the simulation results of the solid particles motion showed that particles with different Stokes number have different spatial dispersion; and that particles with intermediate Stokes number have the largest dispersion ratio. Project (No. G19990222) supported by the Special Funds for Major State Basic Research of China     

A novel low-voltage high precision current reference based on subthreshold MOSFETs

INTRODUCTION With the development of modern electronics,there is a growing trend of designing a low-voltagehigh precision current reference in many mixed-signaland analog circuits such as data converters (Mehr andSinger, 2000; Oh et al., 2004), oscillators and PLLs(Razavi, 2001; Banba and Shiga, 1999). Low-costreasons need the reference to be realized in simplestandard CMOS logic process technology, withoutresorting to the use of BiCMOS process and specialdevices such as floating-g…     

Science Letters： A robust polysilicon-assisted SCR in ESD protection application

A novel polysilicon-assisted silicon-controlled rectifier (SCR) is presented and analyzed in this paper, which is fabricated in HHNEC's 0.18 μm EEPROM process. The polysilicon-assisted SCRs take advantage of polysilicon layer to help bypass electro-static discharge (ESD) current without occupying extra layout area. TLP current-voltage (I-V) measurement results show that given the same layout areas, robustness performance of polysilicon-assisted SCRs can be improved to 3 times of con- ventional MLSCR's. Moreover, one-finger such polysilicon-assisted SCRs, which occupy only 947 μm2 layout area, can undergo 7-kV HBM ESD stress. Results further demonstrate that the S-type I-V characteristics of polysilicon-assisted SCRs are adjustable to different operating conditions by changing the device dimensions. Compared with traditional SCRs, this new SCR can bypass more ESD currents and consumes smaller IC area.     

Orbital milling hole of aerospace Al-alloy with big pitch

To improve the processing efficiency and the quality of orbital milling hole of aerospace Al-alloy, the big-pitch influence on cutting force and hole quality was studied experimentally. First, a program based on horizontal lathe was proposed based on kinematics analysis of orbital milling. Then, the cutting force at different stages and the hole quality with different pitches were measured. Results show that the axial force and radial force increase with the pitch amplification during orbital milling. However, the axial force in the orbital milling hole is about 8—10 times smaller than that in the conventional drilling. The diameter error of milling hole is 48—93 μm, and the surface roughness of milling hole is 1.2—1.7 μm. Finally, an orbital milling device with big pitch was designed.     

Effects of different concentrations of antisense oligodeoxynucleotides (ASODN) on human pancreatic cancer cell line PaTu8988s

Objective: To study the effects of different concentrations of antisense oligodeoxynucleotides (ASODN) on human pancreatic cancer cell line PaTu8988s. Method: Human pancreatic cancer cell line PaTu8988s in exponential growth stage was used to study the effect of different drug concentrations on the cell line in the presence of different concentrations (0 μg/ml, 5 μg/ml, 25 μg/ml, 50 μg/ml, 10 μg/m, 200 μg/ml) of ASODN and sense oligodeoxynucleotides (SODN). Cell counts and 3-[4,5-dimethylthiazolzyl]-2,5-diphenyl tetrazolium bromide (MTT) assays were carried out. Results: The inhibitory rate on the cell line PaTu8988s was 98.73%, 95.76%, 69.49%, 33.05% and 0 for ASODM concentrations of 200 μg/ml, 100 μg/ml, 50 μg/ml, 25 μg/ml and 5 μg/ml at 48 hours. Conclusions: K-ras complementary ASODN can inhibit the growth of human pancreatic cancer cell line PaTu8988s by 30.05% to 98.73%. This is likely to contribute to the specificity of the K-ras mRNA complementary capped ASODN sequential codon. Non-specific effect and side effect of ASOND were observed for instance, the greater the concentration is, the earlier the peak of inhibitory rate is reached. In concentration, of 25 μg/ml to 100 μg/ml ASODN showed a dose-effect correlation.     

灰色理论在某刚构—连续组合梁桥线性监控的应用

将灰色理论应用于刚构——连续组合梁施工线形监控计算中,以前期的实测值与计算的理想桥梁线性的误差序列为原始序列建立灰色预测模型,及时地对已出现的误差进行调整,以确保中、后期各梁段施工线形调控计算和实施的精确度,最终达到竣工后桥梁线形与目标线形的吻合。通过对某刚构——连续组合梁桥监控的实施,使该桥合龙精度和成桥线形均达到了期望的效果。     

双波长一氧化碳激光器差分吸收微机检测系统

双波长一氧化碳激光器差分吸收微机检测系统主要用于微量元素检测和大气污染监测,它采用微机完成对两路差分吸收的激光调幅脉冲信号峰——峰值数据处理。具有高速、高精度实时监测功能,经用户实际使用,系统运行稳定可靠、使微机在激光——大气污染监测的应用领域,达到国内先进水平。     

Optimal design for elliptical holey fiber with stable polarization beat-length

In order to design birefringent holey fiber with beat-length independent of wavelength, an asymmetric structure is introduced to reduce its wavelength-sensitivity. The influence of structural parameters on the modal birefringence is calculated and analyzed. After optimizing the parameters, a flat dispersion curve of beat-length is obtained. The beat-length changes from 89.8 mm to 91.0 mm in wavelength range from 1.1 μm, to 1.7 μm, and its relative variation is 1.38%. If this fiber is made into zero-order qu...     

细长轴双刀车削弯曲变形的分析

为提高细长轴车削加工质量,采用细长轴双刀车削加工方法,建立细长轴双刀车削加工模型,并对细长轴双刀车削进行理论分析.运用ANSYS软件对细长轴双刀车削加工和单刀车削加工进行静力学分析,通过比对二者仿真数据,得出细长轴双刀车削可以大幅度提高工件加工精度的结果,并验证双刀车削加工细长轴的可行性.     

THE LENGTH MEASUREMENT IN THE TURKISH MATHEMATICS CURRICULUM: ITS POTENTIAL TO CONTRIBUTE TO STUDENTS’ LEARNING

“Knowing and doing measurement” is a fundamental competency in real life since measuring attributes of objects in appropriate units and using measuring tools assist students to quantify and understand the world. For this reason, the study of measurement has a special place in every mathematics curriculum. Among the domains of measurement, length measurement is extremely important for students to understand basic ideas about measurement and to construct bases for more advance topics as area and volume measurement. However, research on students’ understanding of length measurement reveals serious difficulties varying from incorrect alignment with a ruler to confusion of perimeter with area. One of the reasons for students’ struggles in measurement is considered as weaknesses in the intended (written) curriculum. In this respect, this study was designed to investigate the content of length measurement in the Turkish mathematics curriculum (1st–fifth grade) in terms of its potential to support students’ understanding. For this purpose, the Turkish Mathematics Curriculum Guide was carefully analyzed by considering main components of the curriculum (e.g. learning objectives). In spite of some weaknesses, the length measurement content in the curriculum seems to provide meaningful opportunities for students to develop the concepts and skills involved in length measurement.