A low power fast-settling frequency-presetting PLL frequency synthesizer

This work presents the design and implementation of a 2.4 GHz low power fast-settling frequency-presetting PLL frequency synthesizer in the 0.18μm CMOS process.A low power mixed-signal LC VCO,a low power dual mode prescaler and a digital processor with non-volatile memory are developed to greatly reduce the power consumption and the setting time.The digital processor can automatically calibrate the presetting frequency and accurately preset the frequency of the VCO under process variations.The experimental results demonstrate that the power consumption of the synthesizer is about 4 mA @ 1.8 V and that the typical setting time of the synthesizer is less than 3μs.

Study on Crack Propagation Parameters of Tunnel Lining Structure Based on Peridynamics

The numerical simulation results utilizing the Peridynamics(PD)method reveal that the initial crack and crack propagation of the tunnel concrete lining structure agree with the experimental data compared to the Japanese prototype lining test.The load structure model takes into account the cracking process and distribution of the lining segment under the influence of local bias pressure and lining thickness.In addition,the influence of preset cracks and lining section formon the crack propagation of the concrete lining model is studied.This study evaluates the stability and sustainability of tunnel structure by the Peridynamics method,which provides a reference for the analysis of the causes of lining cracks,and also lays a foundation for the prevention,reinforcement and repair of tunnel lining cracks.

THE PROSPECT OF COMPUTER-ASSISTED DRUG ADMINISTRATION

The prospect of Computer-Assisted Instant Monitoring drug Administration is discussed based on 8-year experience of exprimental and clinical research. The CAIMA system is composed of a negative feed-back closed loop, with the living organism as a link within the loop. Transducers are of vital importance, and need improvement as to sensitivity and specificity in order to transform the relevant biological phenomena into electrical signal. The range of the Controlled levels should be known in advance. Drugs of short duration, with rapid onset should be chosen for first trials. Slowly acting drugs, with long half lives need special programs with multi-criteria. The total dose, the therapeutic ranges and other relevant doses should be calculated by CAIMA. The possiblility of presetting the reaction level is the most salient feature of CAIMA, which would revolutionize the mode of drug administration. The author’s opinion is that: CAIMA is ideal for phase Ⅰof clinical trials to find the tolerated dose ranges while the drug-sparing property would make a poison most useful in critical situations. The knowledge on CAIMA is scanty and need strong propagation, while the intimate collaboration of clinicians, computer-men, pharmacologists, mathematicians and marketting-people is badly needed.

THE CAIMA SYSTEM

CAIMA is the abbreviation of Computer-Assisted Instant Monitoring drug Administration. CAIMA works on the principle of closed-loop negative feedback. Special programs have been designed to meet the needs of: a) Patients’ safety, b) Response level desired, c) Output necessary for actuating the injecting pump. The pump forces the drug solution to enter the body with high precision. The author shows 8-year experience of using CAIMA system in laboratory and in hospital operating rooms. Experimental studies revealed that: CAIMA system attenuates the overshots and undershots usually present in reaction to drug administration, thus saves the drug and thereby causes less side-efiffeets, while the recovery is also much shortened. CAIMA system provides a greater tolerance to extra-stimuli and preserves the body original reactive sensitivity to drug. The homeostasis in animals is better kept with CAIMA than without. Clinically, the arbitrary hypotension during brain surgery with sodium nitroprusside and the control of muscle relaxation in general surgery with muscle relaxants have been successful using CAIMA system.

Performance of Flexible Warp Knitting Metal Mesh with Notch

Three different kinds of notch involving single edge notch （ SEN）, double edge notch （ DEN ） and central notch （ CEN ） were preset in flexible warp knitting metal mesh, and the tensile properties of notch samples were tested. Three kinds of notch samples＇ sensitivity were investigated through different notch lengths. Then failure process and tensile properties were contrasted and analyzed between intact and notch samples. Experiment and analysis results showed that positive Poisson＇s ratio effect gave rise to obvious waist binding and special inverted triangle loading area. All samples were sensitive to three kinds of notches. And notch sensitivity was closely related to notch form and notch length. The notch procession obviously deteriorated the mechanical properties of flexible warp knitting metal mesh. Sample with different notch lengths and breakage locations determined different tensile strengths that sample could bear. The fitting function of waist binding track satisfied the parabolic equation.

Methods of de-noising the low frequency electromagnetic data

The quality of the low frequency electromagnetic data is affected by the spike and the trend noises.Failure in removal of the spikes and the trends reduces the credibility of data explanation.Based on the analyses of the causes and characteristics of these noises,this paper presents the results of a preset statistics stacking method(PSSM)and a piecewise linear fitting method(PLFM)in de-noising the spikes and trends,respectively.The magnitudes of the spikes are either higher or lower than the normal values,which leads to distortion of the useful signal.Comparisons have been performed in removing of the spikes among the average,the statistics and the PSSM methods,and the results indicate that only the PSSM can remove the spikes successfully.On the other hand,the spectrums of the linear and nonlinear trends mainly lie in the low frequency band and can change the calculated resistivity significantly.No influence of the trends is observed when the frequency is higher than a certain threshold value.The PLSM can remove effectively both the linear and nonlinear trends with errors around 1% in the power spectrum.The proposed methods present an effective way for de-noising the spike and the trend noises in the low frequency electromagnetic data,and establish a research basis for de-noising the low frequency noises.

LM-2D Delivered Chuangxin 1-03 and Shiyan Satellite 4 into Preset Orbit

Two experimental satellites, Chuangxin 1-03 and Shiyan Satellite 4, were put into orbit on a LM-2D launch vehicle from the Jiuquan Satellite Launch Center (JSLC) in northwest China's Gansu Province on November 20.

Hydrodynamic performance of a vertical-axis tidal-current turbine with different preset angles of attack

The instantaneous angle of attack on the blade has a significant effect on the hydrodynamic performance of a vertical-axis tidal-current turbine with straight blades. This paper investigates the influence of different preset angles of attack on the hydrodynamic performance of a three-bladed, vertical-axis, tidal-current turbine both experimentally and numerically. Experiments are carried out in a towing tank. This tested turbine＇s solidity is 0.1146. The preset angles of attack on the blade are -3°, 0°, 3°, and 5°, in the experiments. Experimental results show that with the increase of the preset angle of attack from -3°, to 5°, the hydrodynamic performance of the turbine is improved significantly with the power coefficients being increased from 15.3% to 34.8%, respectively. Compared to the result of a 0° preset angle of attack, the performance of the turbine with positive preset angles of attack is experimentally demonstrated to be beneficial. This performance improvement is also shown by numerical simulations based on the Unsteady Reynolds Averaged Navier-Stokes （URANS） equations. In addition, the numerical results show that the optimal positive preset angle of attack is 7° for the turbine studied. The corresponding power coefficient is 38%. Beyond this optimal preset angle of attack, the hydrodynamic performance of the turbine decreases. Therefore, due to the dynamic stall phenomenon, an optimal preset angle of attack exists for any vertical-axis turbine. This value should be considered in the design of a vertical-axis tidal-current turbine. words：

Coupled Bending-Bending-Axial-Torsional Vibrations of Rotating Blades

In this paper, the coupled bending-bending-axial-torsional free vibrations of rotating blades are investigated based on the Euler-Bernoulli beam model. The coupled partial differential equations governing flapwisc, edgewise, axial and torsional motions are derived by the Hamilton's principle, wherein three types of velocity-dependent terms, namely static centrifugal terms, dynamic centrifugal terms and gyroscopic coupling terms, are focused. The ordinary di& ferential equations are acquired by the Galerkin truncation, and the natural frequencies in all directions and complex mode shapes of the rotating blades are analyzed in detail. It is revealed that the three types of velocity-dependent terms have different effects on the natural frequencies. The natural frequencies are noticeably dependent on the rotating speed and preset angle, except for the axial vibration, which is almost immune to the preset angle. The complex modal motions are displayed by a series of positions of the central line and free-end cross section for different time instants, showing the coupled vibrations among different directions.

Velocity Preset and Transitional Zone′s Shape Optimization for Tailor Rolled Blank

Tailor rolled blank （TRB） is a type of emerging material to produce lightweight vehicle parts. Transitional zoners shape is an important parameter for tailor rolled blank. It not only affects mold design and the local carrying capacity of the stamping parts, but also determines the maximum value and variation characteristics of rolling force. How to get the best transitional zone＇s shape is a key problem for production of tailor rolled blank. A double power function is put forward using for transitional curve, which is continuous and smooth at all connection points inde- pendent of its parameters, so the sudden change of mechanical parameters during rolling and forming process can be avoided. At the same time, the velocity formula and restriction for arbitrary transitional curve are derived to preset vertical velocity of the roller and judge whether the curve can be rolled successfully or not. Then, the finite element method （FEM） is used to verify the precision of velocity formula and study the mechanical characteristics of different curves. Finally, a method to obtain the optimal curve equation is put forward and verified.