Modeling Nd~(3+)-Yb~(3+)-Tm~(3+)-Er~(3+) Codoped Telluride Glass Fiber for 0.4 to 2.0 μm Emission Spectra

The modeling of rare-earth-doped fiber amplifier is accomplished by utilizing the rate and propagation equations of distinct levels for a laser medium. A complex theoretical model for neodymium(Nd~(3+)), erbium(Er~(3+)),thulium(Tm~(3+)) and ytterbium(Yb~(3+)) codoped telluride glass fiber covering 0.4—2.0 μm emission spectra is presented. The emission spectra of Nd~(3+)-Er~(3+)-Tm~(3+)-Yb~(3+)codoped telluride fiber are realized with the excitation of both 808 and 980 nm lasers pumped at 500 mW. Numerical methods are used to calculate the emission spectra covering 0.4—2.0 μm. With the Nd~(3+), Tm~(3+)and Yb~(3+)ion concentrations fixed at 2 × 1020 ion/m~3, the Er~(3+)ion concentration optimized to 8 × 10~(20) ion/m~3 and the fiber length spanning from 0.5 to 2 m, a peak amplified spontaneous emission(ASE) power of 19.8 mW is attainable, and a minimum ASE power of 7.96 mW can also be achieved. The analytical techniques and results indicate that when a telluride codoped fiber with suitable ion concentrations of Nd~(3+), Er~(3+), Tm~(3+)and Yb~(3+)is excited by both 980 and 808 nm pump lasers, 0.4—2.0 μm emission spectra are attainable for vast optical applications.     

Gain and Emission Spectrum Characteristics of 465 nm Laser Diode Pumped Tm~(3+)-Doped Telluride Glass Fibers

Gain and emission spectrum characteristics of Tm~(3+)-doped telluride glass fibers pumped with 465 nm lasers are analyzed. The rate and power propagation equation groups of the fibers are solved numerically and the effects of the fiber parameters including active ion concentration, length and pump power on the gain spectra and amplified spontaneous emission(ASE) spectra are analyzed. The results show that with a pump parameter of 465 nm/200 mW, a doping concentration of 2.5 × 10~(25) ion/m~3 and a fiber length of 16 m, the gain and ASE spectra can cover from 1.100 to 1.900 μm, and the gain and ASE power peaks can reach 52 dB and 8 mW, respectively.     

Theoretical Analysis of Er~(3+)-Doped Telluride Glass Fiber Amplifier for 2.700μm Laser Amplification

The rate equations and power evolution equations of erbium-doped telluride glass fiber amplifier for both 1.530 and 2.700 μm lasers are solved numerically, the dependences of gain spectra on fiber length, dopant concentration and pump power are analyzed, and the gain of 2.700 μm laser is calculated and compared with the experimental result from reference. The numerical analysis shows that with 8 × 10~(24)ion/m~3 erbium ion concentration, 5 m fiber length and 600 mW pump power, the gains at 1.530 and 2.700 μm may achieve 23 d B or so. With larger power pump and higher dopant concentration, a net gain of 17 dB is obtained from the Er~(3+)-doped telluride glass fiber amplifier for 110 mW input signal. This fiber amplifier is promising for both 1.530 μm signal amplification and 2.700 μm laser amplification.     

Gain Properties of Triply-Doped Graphene-Insulator-Graphene Nanosheet Waveguide

Er~(3+)-Tm~(3+)-Pr~(3+)triply-doped graphene-glass-graphene(GGG) nanosheet waveguide amplifier, which is a promising candidate for integrated photonic devices, is modelled and numerically analyzed. The designed waveguide is composed of a triply-doped tellurite glass core. The core is sandwiched between two graphene layers.The rate and power propagation equations of a heterogeneous multi-level laser medium are set up and solved numerically to study the effects of waveguide length and active ion concentrations on amplifier performance at five different input signal wavelengths(1.310, 1.470, 1.530, 1.600 and 1.650 μm). The analytical results show that rareearth ion dopant concentrations at an order of 10~(26) ion/m~3, waveguide length at 0.1 m and pump power at 100 m W can amplify 1.530 and 1.600 μm input signals with 1 μW power up to approximately 20.0 and 24.0 dB respectively.Finite-difference time-domain(FDTD) simulation results show that mode field radius of GGG waveguide is smaller than that of silicon waveguide. Consequently, GGG waveguide with the same pump and signal power and the same gain-medium length can produce higher gain than silicon waveguide.     

Gain and Noise Figure Analysis of Er~(3+)-Doped YAG Transparent Ceramic Microchip Amplifier

The rate equations and the power evolution equations based on excited state absorption(ESA) and cooperative upconversion(CUC) of high concentration erbium-doped yttrium aluminum garnet(YAG) transparent ceramic waveguide amplifier are set up to analyze the effects of the pump power, active ion concentration and waveguide length on the amplifier gain and noise figure(NF). The numerical analysis predicts that with a pump power of 100 mW, an active ion concentration of 1.0 × 10~(26) ion/m~3 and a waveguide length of 3 cm, a small-signal gain of 30 dB and an NF of 5 dB can be achieved in the micro-chip amplifier.     

Performance research of a micro-CCHP system with adsorption chiller

This paper describes a new micro-combined cooling,heating and power(CCHP) system,which is especially suitable for domestic and light commercial applications. It mainly consists of a natural gas-fired internal combustion engine,a silica gel-water adsorption chiller and other heat recovery units. In order to study the energy effciency and economic feasibility,an experimental investigation has been carried out. The experimental system has a rated electricity power of 12 kW,a rated cooling capacity of 9 kW and a rated heating capacity of 28 kW. Evaluation and analysis of the system are discussed in detail. The testing results show that the energy effciency of the overall system depends on different modes. The overall thermal and electrical effciency is over 70%. Higher heat load supplied causes higher effciency of the system. Economic evaluation shows that the micro-CCHP system enjoys a small capital cost and short payback period,which is easily accepted by customers. At current natural gas price of 1.9 RMB/m3(nominal condition) and electric price of 0.754 RMB/(kW·h) ,the total capital cost is only 90 000 RMB with a payback period of 3.21 years.     

A New Full Bridge High Intensity Focused Ultrasound Power System with Harmonic Cancellation

The feasibility of a new full bridge high intensity focused ultrasound(HIFU) amplifier system with harmonic cancellation is evaluated in this study. Harmonic cancellation technique is applied to these power amplifiers, which can eliminate the 3rd harmonic and all even harmonics. Since this technique requires two channels of phase signal to control one channel of power amplifier, the signal generator is required to double its output. The transducer array proposed in this study has 100 elements. So we choose an FPGA chip to generate 200 driving signals, and each channel has a phase resolution of 2ns, less than 1°. The phase signal from the FPGA meets the requirement of driving the power amplifiers. The output waveform of one channel of power amplifier(voltage across the transducer) is evaluated, and shows fewer harmonic components.     

Efficient Design and Optimization Method for Distributed Amplifiers

A novel design and optimization method for distributed amplifiers(DAs)is proposed to make the circuit design more convenient and efficient.This method combines artificial intelligence(AI)optimization with manual design by two loops,i.e.,outer manual loop and inner AI loop.The layout design is followed by AI optimization to take more influencing factors such as parasitic effect into account for the practicability.A DA with three gain cells is designed and optimized in a standard 0.18μm complementary metal-oxide-semiconductor(CMOS)technology to verify the proposed method.With a chip area of only 0.55 mm2,the DA provides 9.8 dB average forward gain from 1 to 15.2 GHz.The output power at 1 dB output compression point is more than 7.7 dBm in the 2-14 GHz frequency band and the peak power-added efficiency(PAE)is 10.6%.The measurement results validate the proposed method as a robust DA design procedure for improving circuit performance and design efficiency.     

A Hemodynamic Study of the Effect of Neuromuscular Electrical Stimulation on Enhancing Popliteal Venous Flow

Neuromuscular electrical stimulation has been studied to be a method of prophylaxis for deep venous thrombosis by activating the calf muscle pump. However, there is little evidence of the effects of different stimulating parameters on hemodynamics and comfort levels. The objective of this paper is to compare the effects of different stimulating parameters(current amplitude, pulse-width) on hemodynamic alterations of the popliteal vein and the comfort levels in a group of fourteen healthy subjects. Doppler ultrasound detection of peak venous velocity and blood volume were taken from baseline, twelve sequential electrical stimulations and foot dorsiflexion for each subject. A visual analogue scale was used to assess the subjects' pain perception of neuromuscular electrical stimulation. The results showed that peak venous velocity and blood volume augmented as current amplitude and pulse-width increased while pain level also increased. A compromise was reached that parameters consisting of an amplitude of 10 m A and a pulse-width of 500 μs would obtain a high-peak venous velocity and blood flow volume with a relatively comfortable perception. In addition, parameters consisting of an amplitude of 20 m A and a pulse-width of 300 μs were also shown to be a promising choice. However, further studies need to be done to validate and enrich these findings.     

Turbo-Coded Modulation of EVRC Speech Encoder with Unequal Error Protection for Fading Channels

The Enhanced Variable Rate Codec (EVRC) is a standard for the Speech Service Opti6n 3 for Wideband Spread Spectrum Digital System, which has been employed in both IS-95 cellular systems and ANSI J-STC-008 PCS (Personal Communications Systems). This paper investigated the combination of turbo codes with Unequal Error Protection (UEP) and 16-QAM modulation for EVRC codec of Rate 1 to get power and bandwidth efficient coding scheme. The results show that the UEP system outperforms the Equal Error Protection (EEP) one by 1.45dB at BER of 10^-5.     

A high-performance low cost inverse integer transform architecture for AVS video standard

A high-performance, low cost inverse integer transform architecture for advanced video standard (AVS) video coding standard was presented. An 8×8 inverse integer transform is required in AVS video system which is compute-intensive. A hardware transform is inevitable to compute the transform for the real-time ap-plication. Compared with the 4×4 transform for H.264/AVC, the 8×8 integer transform is much more complex and the coefficient in the inverse transform matrix Ts is not inerratic as that in H.264/AVC. Dividing the Ts into matrix S8 and R8, the proposed architecture is implemented with the adders and the specific CSA-trees instead of multipliers, which are area and time consuming. The architecture obtains the data processing rate up to 8 pixels per-cycle at a low cost of area. Synthesized to TSMC 0.18 μm COMS process, the architecture attains the operating frequency of 300 MHz at cost of 34 252 gates with a 2-stage pipeline scheme. A reusable scheme is also introduced for the area optimization, which results in the operating frequency of 143 MHz at cost of only 19 758 gates.     

A wireless video capsule endoscopy system: Design and realization

Wireless capsule endoscopy(CE), an image inspection technique, has been an important advancement in the diagnosis of gastrointestinal(GI) tract diseases. A video capsule endoscopy(VCE) system is analyzed in this study. A complementary metal oxide semiconductor(CMOS) analog image sensor is adopted, and other illumination, communication and energy modules are designed for functional realization. Measuring only φ11 mm ×25 mm, the VCE has a total power consumption of 52.5 m W, which enables it to work continuously for 8 h. The in vivo experiment on a living pig indicates that a clear video with high frame rate of 30 f/s can be obtained.     

Calibration for 3D Structured Light Measurement

A calibration procedure was developed for three-dimensional(3D) binocular structured light measurement systems. In virtue of a specially designed pattern, matching points in stereo images are extracted. And then sufficient 3D space points are obtained through pairs of images with the intrinsic and extrinsic parameters of each camera estimated prior and consequently some lights are calibrated by means of multi point fitting. Finally, a mathematical model is applied to interpolate and approximate all dynamic scanning lights based on geometry. The process of calibration method is successfully used in the binocular 3D measurement system based on structured lights and the 3D reconstruction results are satisfying.     

The study of correlative factors to resistin and its regression equation in type 2 diabetes

Objective To study the changes of resistin and the relationship between resistin and other indexes in patients with type 2 diabetes mellitus. Methods Seventy patients with type 2 diabetics were chosen and divided into three groups according to weight index and 15 healthy persons were chosen as controls. ELISA was adopted to determine resistin concentration. Oxydase method was adopted to measure blood sugar. Radio immunoassay was used to measure insulin level. Results Resistin concentration of patient groups r(23.06±9.34)μg/L ] was significantly higher than that of control group [( 9. 89±4. 47) μg/L, P<0. 01 ]. Resistin was positively related to body mass index (r = 0.4 467) and fat distribution (r= 0. 3 314, P<0.01). Resistin was also positively correlated to the area under the curve of sugar tolerance (r=0. 7 063, P<0. 01), negatively related to the insulin resistance index (r=-0. 4 154, P<0.01), but not related to area under the curve of synchronous insulin release (P>0. 05). And a formula was obtainted : Resistin=- 15. 869 0. 339×GAUC 0.790×BMI. Conclusion The level of reslstin in type 2 diabetics is higher. And reslstin is related to other factors. This formula is of great significance for clinical study of diabetic's disor- ders.     

RP-HPLC method for the simultaneous determination of daidzein,genistein and formonetin in Solanum Lyratum Thunb

A rapid method for the simultaneous determination of daidzein, genistein and formonetin in solanum Lyratum Thunb by high performance liquid chromatography (HPLC) was developed. Separation was achieved on a Diamonsil C18 column (250 mm×4.6 mm, 5 μm) with isocratic elution, using a mobile phase of methanol-tetrahydrofuran-water (44∶3∶53, v/v). The wavelength was set at 260 nm and column was maintained at 35 ℃. The linear ranges of daidzein, genistein and formonetin were 1.0-40.0, 0.1-4.0 and 0.1-4.0 μg/mL, respectively. The average recoveries were between 98.4% and 101.3%. This method could be used for the quality control of Solanum lyratum Thunb due to its simplification, reliability, rapidity and excellent precision.     

Flow-injection-enhanced chemiluminescence method for the determination of three β-blockers

Objective To develop a rapid, simple and sensitive chemiluminescence method for the determination of three β-blockers (bisoprolol, atenolol and propranolol). Methods The chemiluminescence of cerium (Ⅳ)-sulfite system was obviously sensitized by adding anyone of three β-blockers in acid media. A new chemiluminescence method was set up by combining with flow-injection technique and used to determine the three β-blockers. Results Good linear ranges were obtained at the concentrations of 2.0×10-7g/mL-4.0×10-5g/mL, 1.0×10-7g/mL-3.0×10-5g/mL and 7.0×10-7g/mL-1.0×10-5g/mL, respectively, with the detection limits of 5.0×10-8g/mL, 7.0×10-8g/mL and 5.0×10-8g/mL (S/N=3), respectively, and the relative standard deviations for 11 times consecutive injections of 1.0×10-6g/mL bisoprolol, atenolol and propranolol were 3.57%, 2.21% and 2.26%, respectively. Conclusion The developed method is sensitive, accurate, rapid and of low cost. And it can be applied to determine bisoprolol, atenolol and propranolol in pharmaceutical preparations.     

FOLLICULO-STELLATE CELLS OFTHE RAT ANTERIOR PITUITARY RESPONDED TO ANGIOTENSIN Ⅱ BY INCREASING INTRACELLULAR CONCENTRATION

Objective The main purpose of this study was to investigate whether the folliculo-stellate cells (FSC) respond to angiotensin(Ang) Ⅱ by increasing intracellular free concentration ([]i) ,and where the o-rigin of mobilization is if that has occurred. Methods Pituitary cells in primary culture were prepared from male Wister rats(250g) by a conventional method and cultured in MEM supplemented with 4％ normal rat serum. Af-ter 2 days in culutre,cells were loaded with 1 μmol/L fura-PE3/AM for 1 h and subjected to a ment with Quanti Cell 700 system. Excitation wavelengths of 340 and 380 nm were selected by means of a computer-controlled filterwheel. Results The of FSC in the rat anterior pituitary was elevated by Ang Ⅱ. The eleva-tion of of FSC induced by 0. 1,1.0,10 and 100 nmol/L Ang Ⅱ was (56.33±6.18), (117.07± 36.07), (175.59 ± 40.01 ) and (216.02 ±11.52) nmol/L, respectively. The increase of of FSC induced by 100nmol/L Ang Ⅱ was not influenced by the medium without (0Ca),but significantly suppressed by thapsigargin (TG),an inhibitor of ATPase. The rate of responsive FSC to Ang Ⅱ (100 nmol/L) was 61.84％ which was obviously higher than that of pituitary endocrine cells (43.49％). Conclusion The present experiment demonstrates that the FSC in the rat anterior pituitary responds to Ang Ⅱ by increasing [which raises the possibility that Ang Ⅱ re-leased from either lactotrophs or gonadotrophs affects FSC through paracrine mechanism. The elevation of [induced by Ang Ⅱ presents a dosage-dependent relation, and is possibly because of the release of from an intra-cellular pool (s). Fashions of release are relative to the concentration of Ang Ⅱ. The results indicate that Ang Ⅱ functions as a paracrine factor among pituitary cells including FSC.